LAUSR

Current guidelines recommend delaying implantation of a primary prevention defibrillator (implantable cardioverter‐defibrillator [ICD]) in patients with a preoperative left ventricular ejection fraction (EF) of ≤35% until at least 90 days after interventional or surgical revascularization both because competing risks may reduce the overall benefit of early device placement and there may be myocardial recovery during this period resulting in an EF>35%, the current cut off for such devices. In this issue of the Journal of Cardiovascular Electrophysiology, Adabag, et al., utilizing data from the Surgical Treatment for Ischemic Heart Failure (STICH) trial, expand on their previous studies characterizing the potential for improvement of myocardial function after surgical coronary revascularization (coronary artery bypass graft surgery [CABG]). The STICH trial, which, importantly, was reported in 2011, was meant to compare the use of then‐current guideline‐directedmedical therapy alone with medical plus surgical therapy (either CABG alone or CABG and surgical ventricular reconstruction) in patients with coronary artery disease, heart failure and a reduced ejection fraction. The present report is limited to the 427 STICH patients, largely white and male, with a preoperative EF≤35%, who underwent surgery (either CABG or CABG and surgical ventricular reconstruction) and had a technically good or excellent assessment of their EF both pre and 4 months postoperatively using the same imaging modality (echo, cardiac magnetic resonance imaging [CMR] or radionuclide ventriculogram). The authors found that nearly 30% of patients had a significant postoperative improvement in EF defined as an EF >35% and an absolute increase from baseline of >5%. In almost 20% the EF improved to >40%, but in only a very small number, 2.3%, was there complete normalization of the EF to >55%. These changes were similar both in those having CABG alone or CABG plus surgical ventricular reconstruction. Significant improvement was, however, 2.2 times more likely (95% confidence interval [CI]: 1.41–3.43; p= .0006) in patients with a preoperative EF≥25% than in those with a lower EF. A full 37.8% of patients with a preoperative EF of 30%–35% had significant improvement while only 20.3% of those with an EF<25% had a similar benefit These findings, while more robust, in that they are based on a larger number of patients in a randomized study, are not inconsistent with previous studies, dating back as far as the 1990s which have shown a meaningful postoperative increase in EF in from 24% to 51% of patients. In none of these studies, including the present one, did patients have the benefit of current optimal guideline‐directed medical therapy including angiotensin–neprilysin inhibitors or sodium–glucose cotransporter 2 inhibitors which might be expected to further increase the number of patients having a “meaningful” improvement in EF—described by the authors as “obviating” the need for a guideline‐directed ICD. Thus, to optimally integrate these findings into our current management we still need more contemporary data on competing survival risks early post‐ CABG, EF recovery, and a better understanding of the meaning of an improved, but less‐than‐normal EF with regard to sudden cardiac death (SCD). Unfortunately, although the STICH trial was initially designed to include a preoperative assessment of myocardial viability, only 40% of the patients in the current analysis had such a study, limiting any conclusions about the utility of such testing in predicting postoperative improvement in myocardial function or SCD prognosis, though the identification of viable myocardium tended to be associated with a greater likelihood of myocardial recovery (33.9% vs. 20.8%; p= .08). In addition, it is well‐documented that SCD, though less common, does continue to occur in patients who have had recovery of their EF to >35%. In the present study, while EF improvement was associated with a 43% lower risk of all‐cause mortality when other variables were controlled for (hazard ratio: 0.57, 95% CI: 0.34–0.94; p = .03), SCD risk was not significantly reduced (hazard ratio: 0.83, 95% CI: 0.35–1.94; p = .66) though the numbers were small. Thus, while validating previous studies and providing us with optimism with regard to the utility of CABG in improving myocardial function and overall survival in patients with significant left ventricular dysfunction and coronary artery disease, Adabag et al.'s study leaves us with three unsettling and still unsettled issues: