New online tool predicts probability of death from stroke

NewsPsychology (Feb. 10, 2011) — Researchers at St. Michael’s Hospital and the Institute for Clinical and Evaluative Sciences (ICES) in Toronto have developed a new tool that will help doctors predict the probability of death in patients after an ischemic stroke.

The study, published in the journal Circulation, found that the tool determined the likelihood of death in stroke patients 30 days and one year after an ischemic stroke. An ischemic stroke, the most common type of stroke, occurs when an artery to the brain is blocked. The tool, available online for doctors at http://www.sorcan.ca/iscore/ , is the first to use risk factors such as heart disease, diabetes, cancer and kidney disease to estimate the probability of death. The findings are being presented at the International Stroke Conference in Los Angeles.

“Doctors today have to rely on anecdotal experience to assess a patient’s prognosis,” says Dr. Gustavo Saposnik, a neurologist at St. Michael’s Hospital and ICES scientist. “However, as doctors we tend to overestimate the likelihood of a good outcome in stroke patients. Now, with our new tool, we can accurately determine what type of outcome our patients may have, which will help guide clinical decisions.”

The study examined 12,262 patients who visited an Ontario hospital from 2003 to 2008 and suffered an ischemic stroke. Using the new tool, researchers determined the death rate 30 days and one year after an ischemic stroke and compared the findings with data from the Ontario Stroke Audit to validate the results. Researchers found the tool was accurate and that risk factors including heart disease, heart failure, cancer, dementia and a history of atrial fibrillation ― an irregular heartbeat ― were associated with a higher probability of death.

“Our tool was developed and validated in the real world,” Dr. Saposnik explains. “This is a tool that helps doctors estimate the risk of a poor outcome in stroke patients, helps families make more informed decisions and can be used by policymakers to accurately compare hospital performance in stroke care.”

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The above story is reprinted (with editorial adaptations by newsPsychology staff) from materials provided by St. Michael’s Hospital.

Journal Reference:

  1. G. Saposnik, M. K. Kapral, Y. Liu, R. Hall, M. O’Donnell, S. Raptis, J. V. Tu, M. Mamdani, P. C. Austin. IScore: A Risk Score to Predict Death Early After Hospitalization for an Acute Ischemic Stroke. Circulation, 2011; DOI: 10.1161/CIRCULATIONAHA.110.983353

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of NewsPsychology or its staff.

Experimental agent better than aspirin at preventing stroke, study suggests

 A new anti-clotting agent is vastly superior to aspirin at reducing stroke risk (1.6 percent per year versus 3.6 percent per year) in atrial fibrillation (AF) patients unable to take stronger drugs, according to final data reported February 10 at the American Stroke Association's International Stroke Conference 2011. Researchers found the drug also works better in people with a history of stroke or a warning stroke.

Atrial fibrillation is a heartbeat abnormality that can cause blood clots which raise the risk of stroke, particularly in the elderly.

The AVERROES: Apixaban Versus Acetylsalicylic Acid (ASA) to Prevent Strokes trial is a randomized trial of 5,600 AF patients at moderate to high risk of stroke who were not willing or able to take oral vitamin-K antagonists like warfarin, a drug commonly prescribed to prevent blood clots in people with AF. They were treated at 520 medical centers worldwide. A May 2010 interim analysis found evidence that the investigational oral drug apixaban was so much more superior to aspirin that the researchers were advised to end the trial early, said Hans-Christoph Diener, M.D., professor and chairman, Department of Neurology and Stroke Center, University Hospital Essen, Essen, Germany.

In releasing the study's final results, he reported that apixaban was far superior to aspirin at preventing stroke or systemic embolism (blood clot) and was also very safe. The drug blocks factor Xa, a crucial step in blood clot formation, said Diener, co-chair of the study's adjudication committee.

"Apixaban was highly superior to aspirin. We had not anticipated that apixaban would show such a big difference compared with aspirin while showing no significant increase in major bleeds," he said. "Everyone had expected that a more powerful drug like apixaban would be associated with more severe bleeding complications compared to aspirin, but it wasn't."

The study's primary endpoint was the reduction of ischemic stroke (stroke caused by blockages in the brain's circulation), hemorrhagic stroke (stroke due to bleeding in the brain) and systemic embolism (blockages due to blood clots elsewhere in the body), he said. The primary safety endpoint was major bleeding incidents.

Up to 50 percent of all AF patients with moderate or high stroke risk are unsuitable for the most effective class of anti-clotting treatment known as vitamin K antagonists (VKA). That class includes the well-known drug warfarin.

All of the AVERROES patients were unsuitable for VKA therapy, which carries an increased risk of hemorrhage and requires frequent blood testing to monitor its effectiveness. For such patients the only alternate treatment is aspirin, which is just modestly effective, Diener said.

The patients in this study, all over age 50, were at moderate to high risk because they had at least one stroke risk factor in addition to AF, such as being age 75 or older, having high blood pressure, heart failure, diabetes or having a history of stroke or transient ischemic attack (a possible precursor of stroke), he explained.

Patients were randomized to receive either apixaban at 5 milligrams (mg) twice a day (2.5 mg twice a day in selected patients) or between 81 mg and 324 mg of aspirin per day. The study's double-dummy design mandated that patients randomized to receive apixaban took an aspirin-placebo and those randomized to receive aspirin got an apixaban-placebo, he explained.

During an average of 1.1 years of follow up, the researchers found 51 strokes or systemic embolism events in the 2,808 patients taking apixaban compared to 113 strokes and systemic embolic events in the 2,791 patients taking aspirin. That represents an annual rate of 1.6 percent for apixaban vs. 3.6 percent for aspirin, meaning apixaban carries about half the relative risk of stroke or systemic embolism compared to aspirin. Although bleeding events were slightly higher with apixaban, the difference fell short of statistical significance.

The researchers will also report on a subgroup of patients with a history of stroke or transient ischemic attack (TIA), often a precursor to stroke.

"If validated by future studies I think this is the end of aspirin as a drug to prevent stroke in patients with AF," he added.

Diener said the study's major limitation is the limited time period of observation, shortened further by the study's early conclusion. "AF patients need anticoagulation for the rest of their lives and we would have liked to see a much longer duration of the trial," he said.

"By evaluating the use of apixaban as a replacement for aspirin in AF patients who are unsuitable for VKA therapy, the AVERROES study is addressing an important unmet clinical need."

Co-authors are Salim Yusuf M.D., Ph.D.; John Eikelboom, M.D.; Martin O. O'Donnell, M.D.; and Stuart J. Connolly, M.D. Disclosures are on the abstract. Bristol-Myers Squibb and Pfizer funded the study.


Journal Reference:

  1. S.J. Connolly et al. Apixaban in Patients with Atrial Fibrillation. NEJM, February 10, 2011 DOI: 10.1056/NEJMoa1007432

MRI can help decide therapy in patients with unclear-onset stroke

Among patients who have had strokes but aren't sure when symptoms began, magnetic resonance imaging (MRI) can help distinguish who might benefit from clot-busting drugs while facing acceptable risk, according to research presented at the American Stroke Association's International Stroke Conference 2011.

Researchers used MRI techniques to screen 430 patients with unclear-onset stroke at six university hospitals in South Korea. Strokes are categorized as unclear-onset, or "wake-up," strokes if patients or witnesses don't know when symptoms began, or woke up already in the throes of a stroke.

It is a key issue because clot-busting drugs have proven effective at reducing disability up to 4.5 hours after symptom onset.

"Wake-up, or unclear-onset, strokes account for a quarter of all ischemic strokes but have been automatically excluded from clot-busting techniques because the onset time cannot be known. Our study shows that such patients could also be treated safely and effectively," said Dong-Wha Kang, M.D., Ph.D., lead author and associate professor in the Department of Neurology at Asan Medical Center at the University of Ulsan College of Medicine in Seoul, South Korea.

All the patients arrived at one of six emergency rooms within six hours of detecting symptoms. Using diffusion-perfusion MRI, which shows tissue death and blood flow in the brain, the researchers looked for sizable areas where tissue remained alive even though it lacked blood flow. To limit the risk of serious bleeding in the brain from clot-busting therapy, patients were excluded if they had extensive tissue death in the brain area supplied by a major artery, the middle cerebral artery, or if other MRI techniques, such as those called FLAIR or T2, showed that the time of tissue death had elapsed.

More than 80 patients (median age 67 and classified as having severe stroke) were found eligible for clot-busting therapy, which included intravenous administration of the drug tissue plasminogen activator (tPA), direct administration of the drug urokinase — which is not available in the United States — to the blocked vessels in the brain or both. Some patients also had their clots removed mechanically or underwent stenting.

Among those who received the drug therapy, about 45 percent had at least a "good" clinical outcome — ranging from no symptoms to slight disability with curtailed activities — on the modified Rankin scale, which measures degree of impairment and its impact on stroke patients' daily activities. Almost 29 percent had an excellent clinical outcome, meaning they were able to carry out all their usual activities with little or no impairment.

A key limitation of the study is it didn't include a comparison group of patients who did not receive the clot busting treatment. Still, Kang said, "This study should trigger follow-up studies to develop the best available treatment strategies for this important but neglected group of stroke patients."

The study also found that female patients were likely to fare more poorly with treatment, as were patients who had a more severe initial assessment of their stroke impairment, and those treated at the two centers lacking previous experience in thrombolysis for unclear-onset stroke.

Because researchers in the study treated patients with strokes of various origins, it's likely that the findings would also apply to non-Korean populations, said Kang. But patient outcomes are likely to vary among medical centers, due to the availability of MRI facilities as well as interventionists to deliver clot-busting drugs directly to the brain blood vessels.

This work received the Emergency Medicine Award from the International Stroke Conference committee — which recognizes outstanding research in the field by a young investigator.

The research team next plans to compare the outcomes from their study population with those of comparable but untreated patients listed in stroke registries. "Although this study provides some important clues to treat wake-up, or unclear-onset, stroke patients, we still have a long way to go to find the best way to treat them," Kang said.

Co-authors are Sung-Il Sohn, M.D., Ph.D.; Kyung-Ho Yu, M.D., Ph.D.; Yang-Ha Hwang, M.D.; Moon-Ku Han, M.D., Ph.D.; Jun Lee, M.D., Ph.D.; Jong-Moo Park, M.D., Ph.D.; A-Hyun Cho, M.D., Ph.D.; Dong-Eog Kim, M.D., Ph.D.; Yong-Jin Cho, M.D., Ph.D.; Jaseong Koo, M.D., Ph.D.; Keun-Sik Hong, M.D., Ph.D.; Sun U Kwon, M.D., Ph.D.; Juneyoung Lee, Ph.D.; Hee-Joon Bae, M.D., Ph.D.; and Jong S Kim, M.D., Ph. Author disclosures are on the abstract. The Korean Health Ministry of Health & Welfare, Republic of Korea funded the study.

U.S. study: Young, uninsured or Medicare Part D survivors often can't afford medicines

Young, uninsured stroke survivors or those covered by the Medicare Part D drug benefit often can't afford medications — increasing the risk for future strokes or other cardiovascular disease-related events, according to research presented at the American Stroke Association's International Stroke Conference 2011.

Researchers evaluated whether cost-related non-adherence to medication was a problem for stroke survivors even after the 2006 implementation of Medicare Part D, a federal government drug benefit that offers prescription drug coverage to all Medicare participants.

"Federal programs to reduce cost-related non-adherence to medication may not be working as intended, and a resulting large number of stroke survivors are at risk for subsequent stroke events," said Deborah A. Levine, M.D., M.P.H., the study's lead author and an assistant professor of medicine at the University of Michigan in Ann Arbor.

"Medicare Part D has not resolved the problem of cost-related non-adherence to medication among Medicare beneficiaries with stroke."

Despite the government prescription coverage, the data suggest that medicine is still unaffordable for some disadvantaged stroke survivors.

Levine and colleagues examined data from 2,656 stroke survivors 45 years and older, and assessed cost-related non-adherence to prescription drugs during the past 12 months. The patients had participated in the National Health Interview Survey conducted between 2006 and 2009.

Researchers compared the patients' responses with survey data collected between 1998 and 2002, before Medicare Part D was implemented. Survey respondents were asked: "Was there any time when you needed prescription medicines but didn't get them because you couldn't afford them?" The survey only included stroke survivors living outside institutional settings, such as hospitals or rehabilitation centers.

Researchers said more people appear to be surviving stroke, but those enrolled in Medicare Part D more often report they can't always afford their medication:

In 2009, 11 percent or about 150,000 stroke survivors reported cost-related non-adherence to their medications. Forty-two percent of Medicare beneficiaries with stroke reported having Medicare Part D. However, cost-related non-adherence to medication was twice as high among Medicare Part D participants compared to those without the prescription drug benefit, 12 percent versus 6 percent. Many Medicare Part D participants were low-income and in poor health. Cost-related non-adherence to medication increased significantly among younger stroke survivors, particularly those ages 45 to 54, but was unchanged among older stroke survivors. Possible reasons include greater competing household costs or less prescription drug coverage among younger stroke survivors, which the researchers could not assess in their study. Cost-related non-adherence among uninsured stroke survivors increased sharply, from 39 percent in 1998-2002 to 60 percent in 2006-09.

Physicians may be able to help reduce the risk of recurrent stroke and other cardiovascular disease-related events among their patients by simply asking them about their abilities to afford their care, Levine said.

"Healthcare professionals need to screen for cost-related barriers to medication in stroke survivors, particularly those who are younger, uninsured or enrolled in Medicare Part D, and to improve access to affordable medications for post-stroke patients who need it," she said.

"Interventions that provide affordable health insurance and that reduce or eliminate costs for medications to prevent recurrent stroke are needed for vulnerable stroke survivors who cannot afford their medications. We hope to study whether full prescription drug coverage of secondary preventive therapies for stroke survivors will improve health outcomes and will be cost effective."

The findings should be interpreted with caution because the data are based on self-reports that didn't include information about stroke timing, the severity of patients' strokes or their attitudes and behaviors about taking medication, Levine said.

Co-authors are Lewis B. Morgenstern, M.D.; Kenneth M. Langa, M.D., Ph.D. and John D. Piette, PhD. Disclosures are on the abstract. There was no external funding.

Robot therapy can improve arm, shoulder mobility after stroke

 Therapy in which robots manipulate paralyzed arms, combined with standard rehabilitation, can improve arm and shoulder mobility in patients after stroke, according to research presented at the American Stroke Association's International Stroke Conference 2011.

Patients on robotic therapy showed marked improvement in two measures of upper extremity function: the Fugl-Meyer flexor synergy score, a 0 to 12 scale with higher numbers reflecting recovery of voluntary arm movement; and the Fugl-Meyer shoulder/elbow/forearm score, a 0 to 36 scale with higher numbers reflecting recovery of motor function in the shoulder, elbow and forearm.

"Combining robotic exercise with regular rehabilitation may be the key to successful intervention," said Kayoko Takahashi, Sc.D., O.T.R., lead author of the study and clinician and research associate in the Department of Occupational Therapy in Kitasato University East Hospital in Kanagawa, Japan. Robots could allow therapists to focus on helping patients master daily activities while maintaining repetitive training, Takahashi said.

The new study involved 60 stroke survivors with hemiplegia (paralysis on one side of the body) treated at six rehabilitation centers in Japan. The patients, average age 65, had suffered a stroke in the previous four to eight weeks. All received standard rehabilitation therapy from an occupational therapist.

Half the group received robotic therapy every day for six weeks, in sessions lasting 40 minutes. The other half spent the same amount of time working through a standard self-training program for hemiplegic patients, performing stretches and passive-to-active exercises of their affected arm.

With a recent trend in helping patients function with one arm, "many post-stroke patients have given up hope of recovery of their affected arms." Takahashi said. "Participating in such robotic exercise is therefore expected to give patients insights about their future ability and a more positive image regarding their affected arm, increasing their self-efficacy and motivation toward rehabilitation."

The group assigned to robotic therapy used a Reo Therapy System by Motorika Ltd. in Israel. For the therapy, the patient's forearm, either resting on or strapped to a platform, is moved in multiple directions based on pre-programmed exercise movements.

Researchers selected five such pre-programmed movements. For instance, in one of the movements, "forward reach," the robot helps patients extend their arms forward as if reaching for something in front of them.

Therapists also selected from five levels of robotic assistance according to what was most appropriate for the patient, from movement entirely guided by the robot and passive on the patient's part, to movement actively performed by the patient.

The successful test of robots adds a new wrinkle to stroke rehabilitation strategies, Takahashi said. While repetitive movement is an essential therapy, physical and occupational therapists aren't always available to provide care, and self-training, if not done correctly, can result in pain and disability.

"Robots, on the other hand, can carry out the repetitive movement exercise with exactly the right movement pattern to prevent misuse," Takahashi said.

Based on initial mobility scores, patients with severe hemiplegia were more likely to benefit from the robotic therapy. The finding is consistent with the notion that higher-functioning patients already can correctly carry out self-training programs, while patients with lower function — only reflex and minor voluntary movement — are more likely to benefit from the support and aid of robots, Takahashi said.

"Further research using larger groups of patients is necessary to investigate the efficacy of such robotic exercise in more detail," Takahashi said.

Co-authors are: Kazuhisa Domen, M.D., D.M.Sc.; Kenji Hachisuka, M.D., D.M.Sc.; Tomosaburo Sakamoto, M.D., Ph.D.; Masahiko Toshima, M.D.; Yohei Otaka, M.D.; Makiko Seto, M.D., Ph.D.; Katsumi Irie, M.D., Ph.D.; Bin Haga, M.D., Ph.D; and Tetsuhiko Kimura, M.D., Ph.D. Author disclosures are on the abstract.

Poorer patients have more severe ischemic strokes, study indicates

 Poorer patients have more severe ischemic strokes, or strokes resulting from blockages in blood vessels in the brain, according to new research from the University of Cincinnati (UC).

A study led by Dawn Kleindorfer, MD, an associate professor in the department of neurology, found that increasing poverty in the neighborhood where the stroke patient lived was associated with worse stroke severity at presentation, independent of other known factors associated with stroke outcomes.

The study is being presented Feb. 9 in Los Angeles at International Stroke Conference 2011, the annual meeting of the American Stroke Association.

The research is part of the Greater Cincinnati/Northern Kentucky Stroke Study, begun in 1993 at the UC College of Medicine, which is funded by the National Institutes of Health (NIH) and identifies all hospitalized and autopsied cases of stroke and transient ischemic attack (TIA) in a five-county region.

Researchers studied 1,933 cases of ischemic stroke from 2005, of which 21.9 percent of the patients were African-American and 52.3 percent were female, with an average overall patient age of 71. Researchers used community poverty levels based on census tract data to estimate individual socioeconomic status.

The poorest community socioeconomic status was associated with a significantly increased initial stroke severity by 1.6 points on a severity scale compared with the richest category, researchers found. The analysis remained significant even after adjustment for demographics and other diseases.

"The magnitude of change in stroke severity for the poorest patients was similar to the effect of having a history of coronary artery disease or high blood pressure," says Kleindorfer, a member of the UC Neuroscience Institute.

Although this study cannot definitively say why poorer patients have more severe strokes, researchers suggest that socioeconomic status might impact stroke severity via access to care, cultural factors, medication compliance or undiagnosed disease states.

Stroke in Mexican-Americans expected to rise 350 percent in next 40 years

Strokes will increase dramatically over the coming decades, with increases being considerably steeper in Mexican-Americans compared with non-Hispanic whites, according to research presented at the American Stroke Association's International Stroke Conference 2011.

"The tremendous number of strokes projected has large personal, social and economic consequences for the United States," said Shawnita Sealy-Jefferson, M.P.H., an investigator at the School of Public Health at the University of Michigan in Ann Arbor.

According to the American Stroke Association, stroke accounts for one out of every 18 deaths and is the third leading cause of death in the country.

Preliminary data released recently by the Centers for Disease Control and Prevention shows stroke has dropped to the fourth leading cause of death, with 795,000 occurring yearly (610,000 of them first-time strokes).

Researchers, who used current trends to calculate the potential burden of stroke during the middle of the 21st century, expect: stroke among Mexican-Americans to rise from about 26,000 in 2010 to more than 120,000 in 2050 — about a 350 percent increase; and stroke among non-Hispanic whites to rise from about 300,000 in 2010 to more than a half million in 2050 — about a 75 percent increase.

The projections are based on data from the U.S. Census and data collected between 2000 and 2008 from the Brain Attack Surveillance in Corpus Christi (BASIC) Project, an ongoing community-based study in southeastern Texas that compares stroke in Mexican-Americans and non-Hispanic whites.

Both hemorrhagic (bleeding) and ischemic (blood clot) stroke were included in the analysis. To calculate the projected numbers of stroke in the future, researchers assumed incidence rates would remain constant over the years. They took annual incidence rates and multiplied these figures by corresponding ethnic, age and sex-specific projected population counts by the decade.

"Efforts to prevent stroke and reduce stroke-related disability in both Mexican-Americans and non-Hispanic whites are critical," said Lynda D. Lisabeth, Ph.D., M.P.H.,co-author and associate professor, Department of Epidemiology, University of Michigan. "Lifestyle changes can reduce one's risk for stroke."

More research is also needed to understand the excess burden among Mexican-Americans, she said. "Further study of stroke in Mexican-Americans may clarify new intervention targets. Our group is currently targeting stroke prevention through Catholic churches, which might be a novel setting for successful intervention in Mexican-Americans."

Other co-authors are: Devin L. Brown, M.D., M.S.; Lewis B. Morgenstern, M.D.; and Melinda A. Smith, Dr.P.H., M.P.H. Author disclosures are on the abstract.

Drug may improve outcomes in mild stroke patients, save $200 million annually

Treating mild strokes with the clot-busting drug approved for severe stroke could reduce the number of patients left disabled and save $200 million a year in disability costs, according to a study presented at the American Stroke Association's International Stroke Conference 2011.

Researchers analyzed hospital records from 437 patients diagnosed with mild ischemic stroke at 16 sites in the Greater Cincinnati/Northern Kentucky region in 2005. The patients arrived at the hospital within the 3.5 hours, well within the 4.5 hour window for treatment with intravenous tissue plasminogen activator (tPA).

The federal government has approved the clot-busting drug for strokes caused by blood clots, known as ischemic stroke, which accounts for 87 percent of all strokes. It's the only acute stroke drug that can reduce disability but remains unproven for treating mild stroke.

"Currently, there is no standard of treatment for patients with the mildest strokes, even if they come into the emergency department quickly enough for intravenous tPA, the only proven treatment for a more serious stroke," said Pooja Khatri, M.D., lead researcher of the study and associate professor in the Department of Neurology and director of acute stroke at the University of Cincinnati Academic Health Center in Ohio.

"The pivotal randomized trials that proved tPA's usefulness excluded mild stroke patients because it was thought that they generally did well and the risk of tPA treatment, which includes a slight but significant risk of life-threatening bleeding in the brain, would not be worth the benefit," she said.

Only four of the mild stroke patients (less than 1 percent) received tPA. The researchers identified 150 of the remaining patients as likely candidates for the drug if the mildness of their stroke was disregarded as a reason to deny them tPA treatment.

Based on the findings, the researchers then excluded those with baseline disability (estimated at 37 percent) and assumed that 8 percent to 13 percent of the remaining mild stroke patients would regain independence after their stroke if tPA was as effective as it was in more serious cases.

Extrapolating to the U.S. population, the researchers said that if tPA proves effective, 2,176 to 3,761 fewer patients would be disabled from mild stroke each year — saving an estimated $200 million in disability expenditures.

In the last five years, researchers conducting several studies have found that about a third of patients who experienced so-called mild strokes remained disabled three months after initial hospitalization.

"It was believed that patients with milder strokes would recover from these events," Khatri said. "These findings raise the question of whether the mildest strokes should be treated with intravenous tPA."

Co-authors are: J.C. Khoury, Ph.D.; Kathleen Alwell, R.N.; Charles J. Moomaw, M.S.; Brett M. Kissela, M.D.; Daniel Woo, M.D.; Matthew L. Flaherty, M.D.; Ope Adeoye, M.D.; Simona Ferioli, M.D.; and Dawn O. Kleindorfer, M.D. Author disclosures are on the abstract.

Delayed-enhancement MRI may predict, prevent strokes, study shows

 Researchers at the University of Utah's Comprehensive Arrhythmia and Research Management (CARMA) Center have found that delayed-enhancement magnetic resonance imaging (DE-MRI) holds promise for predicting the risks of strokes, the third leading cause of death in the U.S.

Their latest study on a novel application of this technology appears in the Feb. 15 issue of the Journal of the American College of Cardiology.

The study included 387 patients who were treated for atrial fibrillation (AF) at either the University of Utah (Salt Lake City) or Clinical Center Coburg (Coburg, Germany). AF is a little known heart rhythm disorder that affects more than 3.5 million Americans and causes more than 66,000 deaths a year. Individuals with AF are two to seven times more likely to suffer a stroke than the general population.

The purpose of the study was to determine if there was an association between an AF patient's heart damage (for example, left atrial [LA] fibrosis), which was detected using DE-MRI, and commonly used markers for the risk of stroke, specifically the CHADS2 index. Although further prospective studies are needed, the preliminary results indicate that DE-MRI-based detection of LA fibrosis is independently associated with prior history of strokes. The findings also provide preliminary evidence that the physiological features of the LA could be used, in addition to clinical features, when identifying stroke risk in patients.

"We believe this method can be a valuable tool for clinicians to use in conjunction with the CHADS2 index for risk analysis and decisions about anticoagulation medications when treating AF patients," said Nassir Marrouche, M.D., associate professor of cardiology and executive director of the CARMA Center and Director, Cardiac Electrophysiology Laboratories, for the University of Utah's Division of Cardiology.

"Potentially, this will lead to improvement in current risk stratification schemes and enhance our understanding of the risks of thromboembolic (stroke) events in AF patients. We also hope this will lead to the development of effective strategies for stroke prevention."

Although the anticoagulant warfarin is highly effective in preventing strokes, the drug also is associated with life-threatening hemorrhaging and requires intensive dosage monitoring. Risk stratification schemes have been developed to tailor anticoagulation therapy to the patients' risk, and the CHADS2 index is the most accepted risk stratification model. Yet while this index is a valuable tool for predicting cerebrovascular events in high-risk patients, clinicians rely more heavily on clinical judgment when predicting thromboembolic risk in moderate-risk patients, a substantial portion of the AF population. The identification of novel, independent risk factors by DE-MRI may supplement existing tools to help guide clinician judgment in better allocating anticoagulation therapeutic strategies, especially with moderate risk AF patients.

The study concluded that LA fibrosis as determined through the use of DE-MRI is "associated with an increased risk of thromboembolism in AF patients. Clinician use of both a CHADS2 index and a quantified measure of atrial fibrosis has the potential to provide a more rigorous risk assessment and improve future risk stratification schemes."


Journal Reference:

  1. Daccarett, Marcos, Badger, Troy J., Akoum, Nazem, Burgon, Nathan S., Mahnkopf, Christian, Vergara, Gaston, Kholmovski, Eugene, McGann, Christopher J., Parker, Dennis, Brachmann, Johannes, MacLeod, Rob S., Marrouche, Nassir F. Association of Left Atrial Fibrosis Detected by Delayed-Enhancement Magnetic Resonance Imaging and the Risk of Stroke in Patients With Atrial Fibrillation. J Am Coll Cardiol, 2011; 57: 831-838 DOI: 10.1016/j.jacc.2010.09.049

Maternal stroke history tied to women's heart attack risk

 — If you're a woman and your mother had a stroke, you may have a risk of heart attack in addition to a higher risk of stroke, according to new research on family history and heart disease published in the American Heart Association journal Circulation: Cardiovascular Genetics.

In a study of more than 2,200 patients, female heart patients were more likely to have mothers who had suffered a stroke than fathers who did.

"Our study results point towards sex-specific heritability of vascular disease across different arterial territories — namely coronary and cerebral artery territories," said Amitava Banerjee, M.R.C.P., M.P.H., the study's lead author and Clinical Research Associate in the Stroke Prevention Research Unit at the University of Oxford in the United Kingdom.

The Oxford Vascular Study included patients who had suffered a stroke or transient ischemic attack (TIA), or had experienced a heart attack or chest pain known as unstable angina. It's the first study in which researchers investigated the link between a relative's stroke and heart disease risk by sex of the patient and sex of the relative.

In a previous study of the same group, researchers found that women face a higher risk of heart attack before age 65 if their mothers have also had a heart attack at an early age. Other research has linked a mother's history of stroke to a daughter's stroke risk.

Understanding such gender-specific risk factors is important because women, despite their lower odds of suffering a heart attack, are more likely than men to die from one, Banerjee said.

"Moreover, traditional risk factors such as high blood pressure, smoking and diabetes don't account for heart attack risk as clearly in women as in men, and tools to gauge risk in women are inadequate," Banerjee said. "There is clearly room for improvement in predicting heart attack risk in women."

The study also found:

  • About 24 percent of the heart attack and angina patients, and roughly the same percentage of the stroke patients, had at least one first-degree relative who had a history of stroke. This indicates that stroke history in these relatives — which included siblings and parents — is as important to a person's risk of heart attack or angina as it is to risk of stroke, Banerjee said.
  • The female patients who had heart attacks or unstable angina, conditions known collectively as acute coronary syndromes, were more likely to have had any female relative than any male first-degree relatives with stroke history. Male patients were the opposite.
  • Parents' stroke history didn't help predict where patients' heart disease showed up on coronary angiography, or whether disease was present in multiple blood vessels. This suggests that whatever family influence is occurring doesn't directly affect the heart's anatomy or dictate where dangerous plaques build up in the coronary arteries. Instead, family history might influence a more general tendency toward thrombosis, or clot production.

The new findings can't be attributed to genetics alone because shared environmental factors such as relatives' wealth or poverty can also influence disease risk, Banerjee said.

The study used multiple avenues to comprehensively identify patients in a six-and-a-half-year period who had a diagnosis of stroke, TIA or acute coronary syndromes.

Researchers gathered data throughout the study rather than retrospectively and the subjects were a more representative group recruited through general practitioners. However, because the subjects are all from the United Kingdom, it's unclear whether the findings would apply to populations in other countries. Ninety-four percent of the population in the Oxford Vascular Study is white, 3 percent Asian, 2 percent Chinese, and 1 percent Afro-Caribbean.

To gather family histories, researchers relied on patients' reports rather than direct interviews with relatives. But studies have shown these reports are generally accurate and are what doctors most often rely on in the clinic.

"Existing tools to predict heart attack risk ignore family history or include it simply as a yes or no question, without accounting for relevant details such as age, sex and type of disease in patients compared with their relatives," Banerjee said. "Family history of cardiovascular disease is under-used in clinical practice."

Co-authors are: Chris C.S. Lim, M.B.B.S.; Louise E. Silver, R.G.N., B.Sc., M.Sc.; Sarah J.V. Welch, R.G.N., B.Sc., M.A.; Adrian P. Banning, M.D.; and Peter M. Rothwell, M.D., Ph.D.