Prevalence and prognostic value of ventricular conduction delay in heart failure with preserved ejection fraction

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation; Health Foundation Limburg BACKGROUND: The pathophysiology of heart failure (HF) with preserved ejection fraction (HFpEF) is heterogeneous and incompletely understood. Identifying phenotypes of HFpEF is a promising approach to determine the underlying pathophysiological mechanisms and to improve treatment. Patients with electrical ventricular conduction delay (VCD) may represent a separate phenotype. OBJECTIVES: To identify a VCD phenotype in HFpEF through assessment of QRS duration and vectorcardiographic QRS area. Moreover, to determine how differences in these VCD indices relate to adverse outcomes. METHODS: Consecutive patients underwent a comprehensive diagnostic work-up at baseline and were diagnosed with HFpEF. Baseline QRS duration was obtained clinically from a standard 12-leads electrocardiography (ECG). QRS area was derived from vectorcardiography analyses of the baseline ECG. Presence of VCD was categorically defined as QRS duration ≥120ms or QRS area ≥69µVs. Adverse outcome comprised a composite of HF hospitalization and cardiovascular mortality. Patients with cardiac devices before and up until one year after baseline were excluded in prognostic analyses. RESULTS: From a total of 346 HFpEF patients included in this study, 71.3% had a QRS duration <100ms compared to 20.1% with QRS duration 100-119ms and 8.6% with QRS duration ≥120ms. Only 3.8% of all patients had a QRS area ≥69µVs, indicating delayed left ventricular lateral wall activation. A history of coronary artery disease was more prevalent in patients with higher QRS duration or larger QRS area. Sex differences were mainly found in those with a QRS duration ≥100ms, which was present in 54.8% of all males and 17.5% of all females. After a median of 2 years follow-up, 16.4% of the patients had an adverse outcome. Longer QRS duration but not larger QRS area was associated with more adverse outcomes on a categorical scale (Figure). In multivariable Cox-regression analyses adjusted for sex and age, QRS duration was an independent predictor of adverse outcomes (hazard ratio per 1ms increase = 1.017, 95% confidence interval 1.004-1.030, P = 0.012) (Table). CONCLUSION: HFpEF patients have a low prevalence of a VCD phenotype, 8.6% have a QRS duration ≥120ms and 3.8% a QRS area ≥69µVs. However, QRS duration >100ms was an independent predictor for adverse outcomes. Thus, future efforts are warranted to understand the biologic and mechanical mechanisms underlying the association of QRS duration and adverse outcomes, and to determine its clinical implications. [Figure: see text] [Figure: see text]