Association of Silent Myocardial Ischemia with New Atherothrombotic Brain Infarction in Older Patients With Extracranial Internal or Common Carotid Arterial Disease with and without Previous Atherothrombotic Brain Infarction

Abstract

OBJECTIVE: To correlate silent myocardial ischemia with the incidence of new atherothrombotic brain infarction (ABI) in older patients with 40 to 100% extracranial carotid arterial disease (ECAD) with and without prior ABI. DESIGN: In a prospective study of 208 older patients with 40 to 100% ECAD diagnosed by carotid duplex ultrasonogra‐phy, 24‐hour ambulatory electrocardiograms were obtained to detect silent myocardial ischemia. At 42‐month mean follow‐up, silent myocardial ischemia was correlated with the incidence of new ABI in patients with and without prior ABI. SETTING: A large long‐term health care facility where 208 older patients with 40 to 100% ECAD and technically adequate 24‐hour ambulatory electrocardiograms for detecting silent myocardial ischemia were studied. PATIENTS: The 208 patients included 68 men and 140 women, mean age 81 ± 8 years (range 60 to 100). One‐hundred three (50%) of the patients had prior ABI. MEASUREMENTS AND MAIN RESULTS: Sixy‐nine (33%) of the 208 patients had silent myocardial ischemia. Mean follow‐up was 42 ± 25 months (range 3 to 101 months). At follow‐up, the incidence of new ABI was 64% in patients with prior ABI and 32% in patients with no prior ABI (P < .0001). At follow‐up, the incidence of new ABI was 65% in patients with silent ischemia and 40% in patients with no silent ischemia (P = .0005). The multivariate Cox regression model showed that patients with prior ABI have a 2.5 times higher chance of developing new ABI than those without prior ABI after controlling other prognostic variables. Patients with silent ischemia have a 2.1 times higher probability of developing new ABI than those without silent ischemia after controlling other prognostic variables. CONCLUSIONS: Prior ABI and silent ischemia are independent risk factors for the development of new ABI in patients with 40 to 100% ECAD. This probably reflects that silent ischemia is a marker for more advanced or more significant atherosclerotic disease rather than a causal factor for ABI.