Background: The incidence, risk factors, and long-term prognosis of new-onset ventricular tachycardia (VT) and ventricular fibrillation (VF) after coronary artery bypass graft surgery (CABG) in patients with impaired left ventricular function have not been thoroughly examined. Methods: This study enrolled 612 consecutive patients with impaired left ventricular function (ejection fraction <50%) undergoing CABG at a single institution between March, 1996, and September, 2015. Outcomes were analyzed and compared, including in-hospital mortality and long-term survival. After a propensity-score, matching was performed to adjust for differences between the two cohorts. Factors significantly associated with VT/VF were also investigated using multivariate logistic regression.
Results: Of the 600 patients included in the analyses, 92 (15.3%; 95% confidence interval [CI] 12.5-18.3%) had new-onset VT/VF postoperatively. Before propensity matching, patients with postoperative VT/VF were more likely to have renal failure, intra-aortic balloon pump support, lower preoperative ejection fraction (EF), and a larger left ventricle than those without VT/VF. Multivariate regression identified three preoperative risk factors and one protective factor that were independently associated with new-onset VT/VF: previous renal failure (odds ratio [OR] 4.42, P = .02), left ventricular end-diastolic dimension enlargement (OR 1.83, P = .03), ejection fraction (OR 1.88, P = .02 for EF ≥30 and <40% versus ≥40% and <50%; OR 5.46, P = .00 for EF <30% versus ≥40% and <50%), and preoperative β-blockers (OR 0.58, P = .03). The median follow-up time was 46.6 months. In the propensity-matched cohorts, survival for patients who had in-hospital VT/VF was lower than that of the non-VT/VF group (89.9% versus 97.6%; P < .05).
Conclusion: This study shows a high incidence of new-onset VT/VF after CABG in patients with impaired left ventricular function. The early and long-term survival rates were significantly lower in the VT/VF group. Preoperative renal failure, left ventricular end-systolic dimension enlargement, and the severity of left ventricular function were independently associated with the development of new-onset VT/VF after CABG surgery. Preoperative use of beta-blocker was proved to be protective in reducing both VT/VF incidence and in-hospital mortality in CABG patients with impaired left ventricular function following CABG. When considering these data, a prescription of beta-blockers is prognostically indicated to CABG patients, especially those with new-onset VT/VF postoperatively.
Keywords: coronary artery bypass grafting; ejection fraction; ventricular fibrillation; ventricular tachycardia.