Native QRS duration and outcomes in heart failure with mildly reduced ejection fraction: results from a large-scaled registry.

Objective: The study investigates the prognostic impact of the native QRS duration in patients with heart failure and mildly reduced ejection fraction (HFmrEF).

Background: The prognostic impact of QRS duration in HFmrEF has rarely been investigated.

Methods: Consecutive patients with HFmrEF and available 12-lead electrocardiogram were retrospectively included at one institution from 2016 to 2022. Patients with QRS duration ≥ 120 ms were compared to patients with QRS duration < 120 ms, further risk stratification was performed comparing patients with left and right bundle branch block (LBBB vs. RBBB). The primary endpoint was all-cause mortality at 30 months, secondary endpoints comprised the risk of HF-related rehospitalization.

Results: In total, 1627 patients with HFmrEF were included with a median QRS duration of 90 ms (i.e., QRS duration ≥ 120 ms: 15%). Although the risk of long-term all-cause mortality was not affected by a prolonged QRS duration (35.1% vs. 28.7%; p = 0.057; HR = 1.254; 95% CI 0.993-1.583), patients with QRS duration ≥ 120 ms had a higher risk of HF-related rehospitalization (18.2% vs. 11.9%; p = 0.008; HR = 1.574; 95% CI 1.124-2.204). A QRS duration ≥ 120 ms was associated with long-term HF-related rehospitalization even after multivariable adjustment (HR 1.420, 95% CI 1.008-2.002, p = 0.045). Finally, the risks of long-term all-cause mortality and HF-related rehospitalization did not differ among patients with LBBB and RBBB.

Conclusion: A prolonged native QRS duration is independently associated with a higher risk of HF-related rehospitalization in HFmrEF, but not long-term all-cause mortality.