1. In individuals suffering from ischemic left ventricular dysfunction with ejection fraction of 35% or lower, neither cardiovascular magnetic resonance imaging nor stress echocardiography was able to pinpoint a group of patients who could gain advantages from percutaneous coronary intervention.
2. The extent of nonviable myocardium was linked to an increased risk of mortality or hospitalization due to heart failure and a reduced likelihood of left ventricular function improvement.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Myocardial viability tests are considered to help identify individuals with ischemic cardiomyopathy who may benefit from revascularization. These tests categorize myocardial tissue into healthy, viable, and nonviable states, and historical data suggest that patients with extensive viability may experience improved left ventricular function and survival after revascularization. In the Surgical Treatment for Ischemic Heart Failure (STICH) trial, random allocation showed no link between viability status and the impact of coronary artery bypass graft surgery. While observational studies hint at potential benefits of revascularization, their retrospective and nonrandomized nature leaves questions about the connection between myocardial viability and outcomes like event-free survival and left ventricular recovery. In this study, the Revascularization for Ischemic Ventricular Dysfunction (REVIVED-BCIS2) trial, involved a randomized comparison of percutaneous coronary intervention (PCI) versus optimal medical therapy (OMT) for ischemic cardiomyopathy patients who had undergone viability testing, aiming to analyze clinical and left ventricular outcomes concerning viable and nonviable myocardium and their associations with prognosis, functional recovery, and the impact of revascularization. The research revealed that viability testing did not pinpoint individuals for whom PCI would offer a prognostic advantage or enhance left ventricular function. A notable advantage of this study was the examination of viability characteristics as continuous variables instead of binary, enabling a more accurate representation of biological diversity and improving the capacity to identify potential interactions.
Click to read the study in JAMA Cardiology
Click to read an accompanying editorial in JAMA Cardiology
Relevant Reading: Myocardial viability testing: all STICHed up, or about to be REVIVED?
In-Depth [randomized controlled trial]: This study was a prospective, multicenter, open-label randomized clinical trial that included 610 participants recruited between August 2013 and March 2020. Eligible participants for the study had a left ventricular ejection fraction of 35% or less, significant coronary artery, and demonstrated myocardial viability, with viability defined as having at least 4 dysfunctional myocardial segments at rest, deemed viable and accessible for revascularization by PCI due to severely diseased coronary arteries. The primary endpoint was a combination of all-cause mortality or heart failure-related hospitalization over a minimum 24-month follow-up period. Secondary endpoints included all-cause mortality, cardiovascular mortality, heart failure hospitalizations, and improvements in left ventricular function at 6 months. In the PCI group, 107 out of 295 participants experienced a primary outcome event, while in the OMT group, 114 out of 315 participants did so (36.3% vs. 36.2%). The difference between the groups was minimal, 0.1% (hazard ratio (HR): 0.99, 95% confidence interval (CI): 0.76-1.29, P = 0.93) and the results were consistent with the entire trial population over a median follow-up of 3.4 years (IQR, 2.3-5.0 years). No interaction was observed between the extent of viable or nonviable myocardium and the impact of PCI on the primary or secondary outcomes. In the entire study population, the extent of viable myocardium showed no significant association with the primary outcome (HR per 10% increase: 0.98; 95% CI: 0.93-1.04, P = 0.56) or any secondary outcome, while the extent of nonviable myocardium was linked to the primary outcome (HR: 1.07; 95% CI: 1.00-1.15, P = 0.48), all-cause mortality, cardiovascular mortality, and improvements in left ventricular function.
Image: PD
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