Predicting adverse cardiovascular outcomes in post‐coronary artery bypass grafting patients using novel ECG frequency analysis of the QRS complex

BACKGROUND: A novel metric called Layered Symbolic Decomposition frequency (LSDf) has been shown to be an independent predictor of ventricular arrhythmia and mortality in patients receiving implantable cardioverter‐defibrillator (ICD) devices. This novel index studies the fragmentation of the QRS complex. However, its generalizability to predict cardiovascular events for other cardiac procedures is unknown. Herein, we investigated the applicability of LSDf as a predictive measure for major adverse cardiovascular events (MACE) in patients receiving coronary artery bypass grafting (CABG). METHODS AND RESULTS: One hundred ninety‐five patients had high‐resolution ECG recorded prior to CABG surgery in 2012/2013 and were followed for a mean duration of 7.32 ± 0.32 years for postoperative cardiovascular outcomes. These outcomes were described as a modified composite of MACE defined as hospitalization for heart failure, ventricular tachycardia, ventricular fibrillation, and cardiovascular death including stroke and cardiac arrest. One hundred seventy‐two patients were included for analysis and 18 patients experienced a postoperative cardiovascular outcome. These patients had significantly increased age (71.3 vs. 64.6 years, p = .007), prolonged QRS duration (113.22 vs. 97.35 ms, p = .003), reduced left ventricular ejection fraction (42.7% vs. 56.5%, p < .001), and lower LSDf percent (13.5% vs. 16.9%, p = .002). Patients with an LSDf below 13.25% were 4.8 (OR 1.7–13.5, p < .001) times more likely to experience a MACE and up to 19.4 (OR 4.2–90.3, p < .001) times more likely to experience a MACE when older than 70 years and an ejection fraction below 50%. CONCLUSION: Layered Symbolic Decomposition frequency may be an applicable metric to predict long‐term cardiovascular outcomes in patients with ischemic heart disease.