By Michael H. Crawford, MD

Professor of Medicine, Chief of Clinical Cardiology, University of California, San Francisco

Dr. Crawford reports no financial relationships relevant to this field of study.

SYNOPSIS: Anomalous origin of coronary arteries from the opposite sinus are encountered more frequently in middle-aged subjects evaluated for coronary artery disease using CT angiography. In a study of 66 such individuals, their prognosis was similar to a matched control group without anomalous arteries, and no characteristics of the anomalous artery or its course were predictive of major adverse cardiac events.

SOURCE: Gräni C, Benz DC, Steffen DA, et al. Outcome in middle-aged individuals with anomalous origin of the coronary artery from the opposite sinus: A matched cohort study. Eur Heart J 2017;38:2009-2016.

Anomalous coronary arteries that arise from the opposite coronary sinus (ACAOS), especially if they pass between the great arteries, have been associated with sudden death in the young, but little information exits on the outcome of middle-aged individuals in whom such anomalies are detected. Investigators from a single center in Switzerland retrospectively identified 68 patients with newly diagnosed ACAOS by coronary CT angiography (CCTA) over a 12-year period ending in May 2015 in patients evaluated for possible coronary artery disease (CAD). These patients were compared to a control group of 399 patients also evaluated for CAD by CCTA between 2007 and 2008 without coronary anomalies who were followed in a study of the prognostic value of CCTA. Exclusion criteria included other cardiac defects or those who met exclusion criteria for CCTA such as irregular heartbeat or iodinated contrast allergy. Each ACAOS patient was matched with two control patients by age, sex, prior coronary revascularization, and the summed coronary stenosis segment score by CCTA.

The primary combined endpoint was first major adverse cardiac event (MACE), which included death, myocardial infarction, and revascularization. The final study population was 66 patients (mean age = 56 years) and 132 matched controls (mean age = 57 years) because two patients were lost to follow-up. Of these 66 patients, 40 underwent an interarterial course (IAC). During a mean follow-up of 49 months for the ACAOS group and 71 months for the control group, MACE occurred in 17% of the ACAOS group and 24% of the controls, resulting in an identical annual rate (5%). The hazard ratio (HR) of ACAOS vs. controls was 0.83, with 95% confidence interval (CI) of 0.43-1.6 (P = NS). In a model controlled for symptoms, the hazard ratio was 0.94 (95% CI, 0.39-2.28; P = NS). Only three patients underwent coronary artery surgery and six percutaneous coronary interventions related to their ACAOS. The presence of IAC or right vs. left ACAOS origin did not alter results. The incidence of obstructive CAD did not differ significantly between the those with ACAOS vs. controls or in anomalous vessels vs. normal origin vessels in the same patients. The authors concluded that outcomes were not different in middle-aged patients with ACAOS vs. those without, even if the ACAOS took an interarterial course.

COMMENTARY

CCTA is used more frequently in low- to intermediate-risk patients evaluated in the ED or outpatient clinics for suspected CAD. Since CCTA performs best in the absence of significant amounts of coronary calcium, it is used most frequently in middle-aged individuals. Consequently, coronary artery anomalies are encountered more frequently, even though they are rare. Often, patients exhibit no significant CAD, so how to manage them is an issue. Many centers are reluctant to exercise test these patients because of the reported increased risk of sudden death. Thus, it is often not clear if myocardial ischemia is causing their symptoms.

After observing such a patient this month, this study peaked my interest. This study is relatively large for one evaluating a rare condition, and it is the first one with a matched control group. The authors showed that outcomes in ACAOS patients were not different than the control group over a mean of almost five years of follow-up and few experienced revascularization. Also, there were no deaths in the ACOAS group, and characteristics of the anomalous artery did not influence the results. Since ACAOS is one of the most common autopsy findings in younger adults and teens participating in sports, how would one reconcile these results? It has been suggested that vessels stiffen with age and are less likely to be compressed by the great vessels. However, it may be that higher-risk individuals already died before middle age. Interestingly, in this study there were only six patients with anomalous left main or left anterior descending (LAD) arteries from the right sinus. These anomalies are believed to present the highest risk. Certain anatomic features of the anomalous arteries, such as IAC, slitlike opening, acute opening angle, intramural course, elliptical lumen, and obstructed opening, have been associated with a worse prognosis, but this was not the case in this study, Also, it has been hypothesized that anomalous arteries might be more susceptible to CAD, but that was not the case in this study.

Currently, middle-aged patients with ACAOS should be treated conservatively unless it is clear that the anomalous vessel is causing any symptoms with which they may present. This is especially the case for anomalous right coronary arteries, but we must be more circumspect with anomalous left main or LAD, since there were few of these anomalies in this study.