Novel dyssynchrony burden index and right ventricular function for mortality risk stratification in right ventricular...

Right ventricular (RV) apical pacing induces electrical and mechanical dyssynchrony, potentially causing adverse remodelling and mortality. The combined prognostic effect of paced QRS duration, RV pacing burden, and RV dysfunction remains insufficiently characterized.

This retrospective cohort study analyzed 180 patients with permanent pacemakers, RV apical pacing, and LVEF ≥40%. RV function was assessed by TAPSE and RV free-wall strain. A dyssynchrony burden index (standardized sum of QRS duration and pacing burden) was developed, alongside a simple 0-2 point score using clinical (QRS >150 ms, burden >40%) and Youden-optimal (>159 ms, >43%) thresholds. ROC, Kaplan-Meier, and Cox regression analyses assessed two-year all-cause mortality.

Twenty patients (11.1%) died. Non-survivors showed higher pacing burden, QRS duration, and impaired RV function (all p < 0.001). The continuous index showed superior discrimination (AUC 0.832) and was an independent Cox predictor (HR 3.886, p < 0.001), as were TAPSE and LVEF. Combining the index with TAPSE or RV strain raised AUC to 0.917 and 0.981. Both point-scores were independently predictive (OR per point 5.17 and 5.31, p < 0.001) with only modestly lower discrimination (AUC 0.777, clinical thresholds, p = 0.005; AUC 0.796, Youden thresholds, p = 0.063, p = 0.063) vs. continuous index. A point score ≤ 1 was highly sensitive (95%, NPV ≥98%) for rule-out, and a score of 2 reasonably specific (71-77%, LR+ 2.8-3.2) for rule-in.

The dyssynchrony burden index is an independent predictor of mortality in RV apical pacing; RV dysfunction adds complementary value. A simplified, bedside-calculable point-based version preserves most of this prognostic information, offering a practical risk-stratification tool.