NEW ORLEANS—Persons with recent stroke and a high Framingham Coronary Risk Score (FCRS) have three times the risk of myocardial infarction and twice the risk of myocardial infarction or vascular death at two years, compared with patients with a low or intermediate FCRS, according to research presented at the 2012 International Stroke Conference. FCRS, however, is not correlated with the risk of recurrent stroke.
Various FCRS components, such as age, smoking, and diabetes, were independently associated with the risk of myocardial infarction in the study. However, FCRS was associated with myocardial infarction even after controlling for the individual components, noted Amytis Towfighi, MD, Assistant Professor of Clinical Neurology at the University of Southern California in Los Angeles and Chair of the Department of Neurology and Associate Chief Medical Officer at Rancho Los Amigos National Rehabilitation Center in Downey, California.
FCRS could be a tool to assist physicians in identifying patients with recent ischemic stroke who have a high risk of myocardial infarction or vascular death at two years. Clinicians could assist these patients by prescribing medication to prevent coronary disease, or by performing coronary diagnostic imaging and revascularization if necessary.
Assessing a New Application of FCRS
“Stroke patients often harbor asymptomatic coronary atherosclerosis, and coronary heart disease is a major cause of death in individuals with a prior stroke,” Dr. Towfighi told Neurology Reviews. To assess whether baseline FCRS among individuals with recent stroke predicted their risk of future myocardial infarction, vascular death, or stroke, she and her colleagues performed a post hoc analysis of the Vitamin Intervention for Stroke Prevention (VISP) trial.
The patient population included 3,680 persons older than 35 who had had a noncardioembolic, nondisabling ischemic stroke within the previous four months. During the randomized controlled trial, patients took either a high or low dose of folic acid, vitamin B6, and vitamin B12. Patients were recruited at 56 sites between 1996 and 2003 and followed up for two years. The results from the VISP trial did not demonstrate high-dose vitamin therapy to be superior to the low-dose regimen in recurrent stroke prevention, so data for all enrolled patients were combined and included in these analyses.
Approximately 31% of the patients in the sample had known coronary disease. Of those without known coronary disease, 37% had an FCRS of at least 20% (ie, high FCRS). After adjusting for numerous known cardiovascular risk factors, individuals with high FCRS were more likely to be overweight and to have high triglyceride and LDL levels. Persons of black or other non-Caucasian race and obese individuals were more likely to have high FCRS after controlling for age and sex, in addition to the other covariates.
Persons with a low or intermediate FCRS had the lowest rates of myocardial infarction, vascular death, and stroke at two years. Patients with a high FCRS had higher rates of those three outcomes. Participants with known coronary disease had the highest rates of myocardial infarction and vascular death, but not of stroke.
FCRS Linked to Future Myocardial Infarction, But Not Stroke
“Since stroke is a more heterogeneous disease than myocardial infarction, it’s not completely surprising that the FCRS, which reliably predicts risk of future myocardial infarction or vascular death (and not stroke) in the general population, did not predict recurrent stroke in this population,” said Dr. Towfighi.
Dr. Towfighi noted several limitations of her group’s study. “Since it is based on a trial population, it’s not representative of all stroke patients, and, of course, unmeasured confounding is possible,” she said. Because the study was post hoc, the investigators could only assess variables that the conductors of the trial had collected. “In addition, FCRS does not include nontraditional risk factors, which may be more predictive of myocardial infarction in older individuals,” Dr. Towfighi added.
The rigorous procedures of the trial design, however, were among the study’s strengths. The multiple measurements of, and contacts with, each subject, the consistent direction of the effect in all outcomes, and participants’ similarity to patient populations in more recent trials were additional strengths, noted Dr. Towfighi.
The investigators will attempt to validate their findings in a prospective study of patients who are representative of the general stroke population. The team also will seek to determine which interventions can lower the risk of subsequent myocardial infarction or vascular death in patients with recent stroke. “Assessing risk-factor stratification tools predicting the risk of recurrent stroke would be necessary,” concluded Dr. Towfighi.
—Erik Greb
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