Diagnosis and management of silent coronary ischemia in patients undergoing carotid endarterectomy

Abstract

Background: Coronary artery disease is the primary cause of death in patients with carotid artery disease and silent ischemia is a marker for adverse coronary events. A new noninvasive cardiac diagnostic test, coronary computed tomography-derived fractional flow reserve (FFR_CT) can reliably identify ischemia-producing coronary stenosis in patients with coronary artery disease and help to select patients for coronary revascularization. The purpose of this study is to determine the prevalence of silent coronary ischemia in patients undergoing carotid endarterectomy (CEA) and to evaluate the usefulness of FFR_CT in selecting patients for coronary revascularization to decrease cardiac events and improve survival.

Methods: Patients with no cardiac history or symptoms admitted for elective CEA were enrolled in a prospective, open-label, institutional review board-approved study and underwent preoperative coronary computed tomography angiography (CTA) and FFR_CT with results available to physicians for patient management. Lesion-specific coronary ischemia was defined as FFR_CT of 0.80 or less distal to a focal coronary stenosis with an FFR_CT of 0.75 or less, indicating severe ischemia. Primary end point was incidence of major adverse cardiovascular events (MACE; defined as cardiovascular death, myocardial infarction, or stroke) at 30 days and 1 year.

Results: Coronary CTA and FFR_CT was performed in 90 CEA patients (age 67 ± 8 years; male 66%). Lesion-specific coronary ischemia was found in 51 patients (57%) with a mean FFR_CT of 0.71 ± 0.14. Severe coronary ischemia was present in 39 patients (43%), 26 patients had multivessel ischemia, and 5 had left main disease. CEA was performed as scheduled in all patients with no postoperative deaths or myocardial infarctions. There were no MACE events at 30 days. After recovery from surgery, 36 patients with significant lesion-specific ischemia underwent coronary angiography with coronary revascularization (percutaneous coronary intervention or coronary artery bypass grafting) in 30 patients (33%). Survival at 1 year was 100% and freedom from MACE was 98%.

Conclusions: Patients undergoing CEA have a high prevalence of unsuspected (silent) coronary ischemia, which may place them at risk for coronary events. Preoperative diagnosis of silent ischemia using CTA and FFR_CT can identify high-risk patients and help to guide patient management. Selective postoperative coronary revascularization of patients with significant ischemia may decrease the risk of cardiac events and improve survival, but longer follow-up is needed and prospective, controlled trials are indicated.

Keywords: Carotid artery disease; Carotid endarterectomy; Coronary CT-derived fractional flow reserve; Coronary revascularization; Preoperative cardiac evaluation; Silent myocardial ischemia; Survival analysis.