Abstract
Background
In patients with non-ischaemic systolic heart failure (HF) and left bundle branch block (LBBB), the systolic phase of the left ventricular (LV) volume/time (V/t) curve at cardiac magnetic resonance (CMR) can display a wide or a narrow pattern (WP/NP). The clinical and prognostic significance of these patterns are currently unknown.
Methods
Consecutive patients with systolic non-ischaemic HF (LV ejection fraction <50%) and LBBB were enrolled. They underwent a baseline evaluation including CMR, and were periodically re-evaluated during follow-up. The endpoint was a composite of cardiovascular death, heart failure (HF)-related event, and ventricular arrhythmias requiring defibrillator shock.
Results
Out of 101 patients (mean age 64±11 years, males 50%), NP was found in 29 and WP in 72, with no difference in QRS duration. Patients with WP had worse clinical presentation and greater LV volumes, but similar LGE prevalence, extent or distribution. The WP subgroup displayed a greater maximal dyssynchrony time, expressed both as absolute duration (192±80 vs. 143±65 ms, P<0.001), and as percentage of the RR interval (25±11% vs. 8±4%, p<0.001). Even the systolic dyssynchrony index was higher in patients with WP (13±4 vs. 7±3%, p<0.001). The contractility index was lower in patients with the WP (2.6±1.2 vs 3.2±1.7, p<0.05). Over a median follow-up duration of 44 months (interquartile interval 23–59), only WP (p=0.029) and NT-proBNP (p=0.004) demonstrated an independent prognostic value for cardiac events.
Conclusions
In patients with non-ischaemic systolic HF and LBBB, the WP of V/t curves identifies a subgroup of patients with greater LV dyssynchrony, worse clinical conditions and prognosis.
Left ventricular mechanical dyssynchrony by cardiac magnetic resonance is greater in patients with strict vs nonstrict electrocardiogram criteria for left bundle-branch block
