Real-time three-dimensional systolic dyssynchrony index predicts pacing-induced left ventricular dysfunction and...

Right ventricular pacing leads to left ventricular (LV) dyssynchrony, which is a critical factor in the pathophysiology of pacing-induced LV dysfunction (PIVD) and cardiomyopathy (PICM).

This study aimed to determine the incidence of PIVD and PICM and evaluate the prognostic value of the real-time three-dimensional echocardiography (RT3DE)-derived systolic dyssynchrony index (SDI), measured shortly after pacemaker implantation, in predicting their development.

In this prospective observational study, 108 patients undergoing permanent RV pacing. Only 60 patients with preserved baseline LV ejection fraction (LVEF ≥ 50%) were enrolled. Comprehensive echocardiography, including global longitudinal strain (GLS) and RT3DE for SDI (Tmsv 16-SD) calculation, was performed at baseline, 7-10 days, and 6 months post-implantation. Patients were classified at 6 months as preserved (LVEF reduction ≤ 10%, final LVEF ≥ 50%), PIVD (LVEF reduction > 10%, final LVEF ≥ 50%), or PICM (LVEF reduction > 10%, final LVEF < 50%).

The patients' mean age was 62.4 ± 16.3 years, 32 patients were males (53.3%). Mean follow-up was 6.53 ± 0.75 months. Twenty-five patients (41.7%) developed LV impairment; of them, 16 (85%) patients had PIVD, and nine (15%) patients had PICM. While baseline characteristics were similar, the dysfunction group exhibited significantly higher SDI and worse GLS as early as 7-10 days post-pacing. At 6 months, there were significant differences between the preserved group (35 patients) and impaired LV group regarding LV EF (63.6 ± 5 vs. 49.8 ± 11.6, p < 0.001), GLS (- 15.6 ± 3 vs. - 10.9 ± 3.8, p < 0.001), SDI% (2.4 ± 1.2 vs. - 7.9 ± 5.9, p < 0.001), and excursion (5.8 ± 2.23 vs. 3.2 ± 2.1, p < 0.001). In multivariate analysis, both SDI (odds ratio [OR], 5.38; 95% CI, 1.56-18.52; p = 0.008) and GLS (OR, 1.39; 95% CI, 1.02-1.90; p = 0.040) at 7-10 days were independent predictors of 6-month dysfunction. Receiver operating characteristic analysis showed that an SDI > 1.49% predicted dysfunction with an area under the curve of 0.843 (84% sensitivity, 71% specificity). A clear gradient of worsening SDI and GLS was observed from Preserved to PIVD to PICM.

Mechanical dyssynchrony quantified by RT3DE-derived SDI is a powerful, independent predictor of pacing-induced LV dysfunction, identifiable within the first week after implantation. This early measurement offers a critical opportunity for risk stratification and guided intervention to prevent the progression to overt cardiomyopathy.