Early evaluation of coronary artery disease (CAD) in asymptomatic patients with severe aortic stenosis (AS) and risk factors for CAD should be incorporated into practice and guidelines to ensure that timely aortic valve replacement (AVR) and CABG is performed before ischemic myocardial damage occurs, recommended authors of a study in the Feb. 26 issue of the Journal of the American College of Cardiology.
Current guidelines recommend bypass of all significant stenoses at the time of AVR, with evidence level C (J Am Coll Cardiol 2008;52:e1-e142). However, the addition of CABG to AVR is associated with elevated short- and long-term mortality (J Card Surg 2009;24:637-643). This association may be causal (e.g., by increasing myocardial ischemic time) or simply a marker for a high-risk patient profile, according to the study authors, who added that clarifying this may lead to more targeted diagnostics, therapy and chronic disease management.
In this study, Jocelyn M. Beach, MD, of the Cleveland Clinic, and colleagues sought to contrast risk profiles and compare outcomes of patients with severe AS and CAD who underwent AVR and CABG with those of patients with isolated AS who underwent AVR alone.
From October 1991 to July 2010, 2,286 patients underwent AVR and CABG and 1,637 AVR alone. The researchers developed a propensity score and used it for matched comparisons of outcomes (1,082 patient pairs). They performed analyses of long-term mortality for each group, then combined them to identify common and unique risk factors.
Patients with AS and CAD versus isolated AS were older, more symptomatic and more likely to be hypertensive. The patients with the additional disease burden had lower ejection fraction and greater arteriosclerotic burden but less severe AS, the authors reported. Hospital morbidity and long-term survival were poorer (43 percent vs. 59 percent at 10 years).
Both groups shared many mortality risk factors; however, early risk among patients with AS and CAD reflected effects of CAD; late risk reflected diastolic left ventricular dysfunction expressed as ventricular hypertrophy and left atrial enlargement. Patients with isolated AS and few comorbidities had the best outcome, those with CAD without myocardial damage had intermediate outcome equivalent to propensity-matched isolated AS patients, and those with CAD, myocardial damage and advanced comorbidities had the worst outcome.
The researchers reported that further analyses using propensity matching clearly identified distinct patient subgroups with differing prognosis. The first comprised patients with isolated AS who had the best outcome and whose survival was adversely affected by left ventricular hypertrophy and diastolic dysfunction. The second comprised patients with CAD without evidence of ischemic myocardial damage. These patients had outcomes similar to those with isolated AS and similar non-CAD comorbidities. The third group comprised patients with severe AS and CAD and ischemic damage and multiple comorbidities, unlike patients with isolated severe AS. They had the poorest survival, despite the least degree of AS.
Based on their findings, Beach et al concluded that the “common practice of advocating delay of surgery for patients with AS in order to avoid anticoagulation associated with mechanical prostheses can adversely affect long-term survival because of the potential for myocardial ischemic damage.”
“Elderly patients with AS and risk factors for CAD should be considered for active investigation of CAD before evaluation for AVR,” the researchers recommended. “In contrast, patients with poor functional status and advanced comorbidities may be best served with medical management alone.”
This work was supported by awards from the American Heart Association and support from the Donna and Ken Lewis Chair in cardiothoracic surgery and the Kenneth Gee and Paula Shaw, PhD, Chair in heart research.