Prognostic Value of Mid-Range QRS Duration in Patients With Heart Failure With Reduced Ejection Fraction

BACKGROUND: Prolonged QRS is an established marker of adverse outcomes in patients with heart failure with reduced ejection fraction (HFrEF). However, the prognostic significance of modest QRS prolongation (120-149 ms; mid-range QRS) remains unclear, especially in patients without cardiac implantable electronic devices (CIEDs). This study assessed the natural prognosis associated with mid-range QRS compared with narrow QRS (<120 ms) in a recent Asian cohort of patients with HFrEF. METHODS AND RESULTS: We analyzed patients with HFrEF from the Epidemiological Multicenter Study for Tailored Treatment in Heart Failure (ELMSTAT-HF; January 2020-October 2023). QRS was measured from 12-lead electrocardiograms. Patients with wide QRS (≥150 ms) or CIEDs were excluded. The primary outcome was a composite of all-cause mortality and heart failure hospitalizations. Multivariable Cox models adjusted for the MAGGIC risk score and log-transformed N-terminal pro B-type natriuretic peptide were used. Among 415 patients, 328 had narrow QRS and 87 had mid-range QRS. Over a median follow-up of 547 days, the primary outcome occurred more frequently in the mid-range QRS group (34.5% vs. 12.5%; P<0.001). Mid-range QRS remained independently associated with adverse outcomes (hazard ratio 3.12; 95% confidence interval 1.91-5.11), consistent across non-left bundle branch block (LBBB) and LBBB subgroups. CONCLUSIONS: Mid-range QRS is an independent predictor of adverse outcomes in HFrEF, even in the absence of LBBB.