Commentary
Coronary artery disease is the most common cause of heart failure with reduced ejection fraction and an important cause of mortality.1 Patients with ischemic cardiomyopathy with reduced ejection fraction are often considered for revascularization in addition to OMT and device therapies. Although there have been multiple retrospective studies and registries suggesting that cardiac outcomes and LVEF improve with revascularization, the number of large-scale prospective studies that assessed this clinical question and randomized patients to revascularization plus OMT compared to OMT alone has been limited.
In the Surgical Treatment for Ischemic Heart Failure (STICH) study,2,3 eligible patients had coronary artery disease amendable to CABG and a LVEF of 35% or less. Patients (N = 1212) were randomly assigned to CABG plus OMT or OMT alone between July 2002 and May 2007. The original study, with a median follow-up of 5 years, did not show survival benefit, but the investigators reported that the primary outcome of death from any cause was significantly lower in the CABG group compared to OMT alone when follow-up of the same study population was extended to 9.8 years (58.9% vs 66.1%, P = .02). The findings from this study led to a class I guideline recommendation of CABG over medical therapy in patients with multivessel disease and low ejection fraction.4
Since the STICH trial was designed, there have been significant improvements in devices and techniques used for PCI, and the procedure is now widely performed in patients with multivessel disease.5 The advantages of PCI over CABG include shorter recovery times and lower risk of immediate complications. In this context, the recently reported Revascularization for Ischemic Ventricular Dysfunction (REVIVED) study assessed clinical outcomes in patients with severe coronary artery disease and reduced ejection fraction by randomizing patients to either PCI with OMT or OMT alone.6 At a median follow-up of 3.5 years, the investigators found no difference in the primary outcome of death from any cause or hospitalization for heart failure (37.2% vs 38.0%; 95% CI, 0.78-1.28; P = .96). Moreover, the degree of LVEF improvement, assessed by follow-up echocardiogram read by the core lab, showed no difference in the degree of LVEF improvement between groups at 6 and 12 months. Finally, although results of the QOL assessment using the Kansas City Cardiomyopathy Questionnaire (KCCQ), a validated, patient-reported, heart-failure-specific QOL scale, favored the PCI group at 6 and 12 months of follow-up, the difference had diminished at 24 months.
The main strength of the REVIVED study was that it targeted a patient population with severe coronary artery disease, including left main disease and severely reduced ejection fraction, that historically have been excluded from large-scale randomized controlled studies evaluating PCI with OMT compared to OMT alone.7 However, there are several points to consider when interpreting the results of this study. First, further details of the PCI procedures are necessary. The REVIVED study recommended revascularization of all territories with viable myocardium; the anatomical revascularization index utilizing the British Cardiovascular Intervention Society (BCIS) Jeopardy Score was 71%. It is important to note that this jeopardy score was operator-reported and the core-lab adjudicated anatomical revascularization rate may be lower. Although viability testing primarily utilizing cardiac magnetic resonance imaging was performed in most patients, correlation between the revascularization territory and the viable segments has yet to be reported. Moreover, procedural details such as use of intravascular ultrasound and physiological testing, known to improve clinical outcome, need to be reported.8,9
Second, there is a high prevalence of ischemic cardiomyopathy, and it is important to note that the patients included in this study were highly selected from daily clinical practice, as evidenced by the prolonged enrollment period (8 years). Individuals were largely stable patients with less complex coronary anatomy as evidenced by the median interval from angiography to randomization of 80 days. Taking into consideration the degree of left ventricular dysfunction for patients included in the trial, only 14% of the patients had left main disease and half of the patients only had 2-vessel disease. The severity of the left main disease also needs to be clarified as it is likely that patients the operator determined to be critical were not enrolled in the study. Furthermore, the standard of care based on the STICH trial is to refer patients with severe multivessel coronary artery disease to CABG, making it more likely that patients with more severe and complex disease were not included in this trial. It is also important to note that this study enrolled patients with stable ischemic heart disease, and the data do not apply to patients presenting with acute coronary syndrome.