Prognostic value of left ventricular ventricular dyssynchrony in left bundle branch block patients
Abstract Funding Acknowledgements Type of funding sources: None. Background Patients with left bundle branch block (LBBB) patterns on the electrocardiogram include a heterogeneous group of patients with different prognosis and some of them with or without left ventricular mechanical dyssynchrony (LVMD). LVMD obtained by gated technetium 99m single photon emission computed tomography (SPECT) imaging could be an early tool to detect myocardial damage, identifying a high risk group. Purpose The aim of this study was to assess the prognostic value of LVMD in LBBB patients. Methods Five hundred and eighty consecutive patients with LBBB were referred for gated SPECT from August 2011 to June 2019. Phase analysis parameters Standard deviation (SD) and histogram bandwidth (HB) were obtained in rest gated SPECT imaging. LVMD was defined as the upper limit of the highest normal for phase analysis results in our control patients mean values plus two standard deviations (SD ≥ 21° or HB ≥ 67°). Follow up was performed by telephone contact or medical history review. Hard endpoint was all-cause death. Event-free survival curves were obtained. Univariate and multivariate regression analysis were performed. Results LVMD was observed in 254 (44%) patients. Compared to non LVMD patients had: similar age (67.68 ± 11.01 vs. 67.2 ± 10.3 y; p NS), more male (75.2% vs 39.6%), more hypertension (75.2% vs. 66.8%), more diabetes (22.8% vs. 13%) and more smoking history (31.9% vs. 23.7%) all p <0.05. A total of 495 patients completed the follow up (mean 29.8 ± 25.8 months). Fourteen patients died (2.8%), 12 had LVMD. Fig 1 shows Kaplan-Meier curve of event-free survival in relation to LVMD. Variables associated with all-cause death in the univariate analysis were: Score Rest Summed ≥ 4 (p 0.02), LV ejection fraction ≤ 35% (p < 0.01), diabetes (p 0.03) and LVMD (p <0.01). The absence of LVMD was a predictor of the lower risk of all-cause death in the multivariate analysis (adjusted hazard ratio: 0.13, 95% confidence interval: 0.03- 0.56; p < 0.01). Conclusion In our population of patients with LBBB, the absence of LVMD assessed by gated SPECT imaging identifies patients with lower risk of hard adverse events.