Reevaluation of transient ischemic attacks as a risk factor for early mortality.

The prevailing belief that transient ischemic attack is a risk factor for cardiovascular morbidity and mortality is based primarily on comparisons of survival of patients after transient ischemic attacks to that of an age-, race-, and sex-adjusted general population. Concomitant conditions that carry a high risk of premature mortality or morbidity, such as ischemic heart disease, hypertension, and diabetes, are very prevalent among patients with transient ischemic attacks. Hence, the poor prognosis of such patients may be attributable to these factors rather than their transient ischemic attack per se, which may only serve to bring patients into the medical system. We compared the survival of 336 patients after transient ischemic attack to that of a control group with a similar risk factor profile consisting of 6,710 patients evaluated for cardiac catheterization. Survival estimates, both unadjusted and adjusted for risk factors, did not differ between the two groups. Three-year survival estimates, after adjustment to the mean value of covariates, were 94% for the patients with transient ischemic attacks and 91% for the controls. These results suggest that the transient ischemic attack may not be an independent risk factor for mortality, although it may identify patients already at increased risk from coexisting conditions.