CRT: long-term response and predictors of mortality in left ventricular-only fusion pacing
A A Faur-Grigori, D D Anutoni, A M Bumbar, M Morenci, L Cirin, C Vacarescu, S Crisan, C T Luca, D C CozmaAbstract
Background
Left ventricular (LV)-only fusion pacing represents a physiological alternative to conventional biventricular pacing in patients with preserved atrioventricular conduction. However, long-term survival data and predictors of sustained benefit remain limited.
Methods
We retrospectively analyzed 120 CRT patients with LV-only fusion pacing implanted between 2011 and 2024. The mean age was 67 ± 9.6 years, 56.7% were men, and 89.2% had non-ischemic cardiomyopathy. Baseline data : mean LV ejection fraction (LVEF) was 28 ± 6%, LV end-diastolic volume (LVEDV) was 247 ± 90 mL, and QRS duration was 164 ± 18 ms. A total of 65% received CRT-P and 35% CRT-D systems. Responders were defined as patients showing either an increase in LVEF > 5% or a reduction in LV end-systolic volume (LVESV) > 10% at follow-up.
Results
During a mean follow-up of 67 ± 45 months, all-cause mortality was 23%. Median survival was not reached, as fewer than half of the patients experienced an event, and the mean estimated survival time was 125 ± 7 months (95% CI 111-139). Overall, 64% of patients met the echocardiographic response criteria. Responders demonstrated significantly better event-free survival compared with nonresponders (log-rank=0.586, p=0.001). There was no correlation between mortality and ischemic etiology (p=0.775), changes in LVESV (p=0.91), left atrial volume (LAV) (p=0.47), mitral regurgitation severity (p=0.91), or QRS narrowing (p=0.20). In univariate Cox analysis, only improvement in LVEF significantly predicted survival (HR 0.93, 95% CI 0.89-0.97, p=0.001), corresponding to an approximately 7% reduction in mortality risk per 1% EF increase. In multivariate analysis, LVEF remained the only independent predictor of long-term survival (HR 0.93, 95% CI 0.88-0.98, p=0.017).
Conclusions
Over a decade-long follow-up, LV-only fusion pacing provided durable clinical and survival benefits in patients with preserved AV conduction. Echocardiographic response, defined by systolic and volumetric reverse remodeling, was the strongest and only predictor of long-term survival. Further studies are warranted to identify refined markers capable of predicting sustained mid- and long-term outcomes in patients with LV-only fusion pacing.