Predictive Value of QRS Fraction for Cardiovascular Death in Patients with Heart Failure: A Prospective Cohort Study in Acute Decompensated Heart Failure (Heb-ADHF)

Background: The QRS fraction is the ratio of the total amplitude of R waves to the total amplitude of QRS complexes ( Sigma R/QRS) on a 12-lead electrocardiogram. Our group has previously proposed calculation of the QRS fraction as a simple method for estimation of left ventricular ejection fraction. In this study, we explored the ability of the QRS fraction to predict cardiovascular death in patients with heart failure. Methods: The study had a prospective, observational design and collected epidemiological and follow-up data for 1715 patients with heart failure who were inpatients in the Department of Cardiology at the Second Hospital of Hebei Medical University between January 2017 and December 2018. The patients were stratified according to quartile of QRS fraction, namely, lower (<43.8%, Q1 group) middle (43.8%-61.0%, Q2 group), and higher (>61.0%, Q3 group). Results: One thousand and fifty-one (61.28%) of the 1715 patients were male and the median follow-up duration was 261 days (interquartile range 39, 502). There were 341 (19.88%) deaths, including 282 (16.44%) with a cardiovascular cause. The Q1, Q2, and Q3 groups comprised 431 (25.13%), 850 (49.56%), and 434 (25.31%) patients, respectively. There were significant differences in cardiovascular mortality among the three QRS fraction subgroups (p < 0.05). Kaplan-Meier survival curves of different QRS fraction levels showed significant diffference among patients with heart failure, especially among those with preserved ejection fraction (p = 0.025 and 0.031, log-rank test). Cox regression analysis showed that the QRS fraction was independently associated with the risk of cardiovascular death. The risk of cardiovascular death was lower in the Q2 and Q3 groups than in the Q1 group, with respective hazard ratios of 0.668 (95% confidence interval 0.457-0.974) and 0.538 (95% confidence interval 0.341-0.849). Conclusions: The QRS fraction may serve as a prognostic indicator of the long-term risk of cardiovascular death in patients with heart failure, especially those with preserved ejection fraction.