Conventional cardiac resynchronization therapy upgrading and its effect on functional mitral regurgitation in patients with pacing-induced cardiomyopathy.

BACKGROUND

Data on the effects of conventional cardiac resynchronization therapy (CRT) upgrading by implantation of a left ventricular lead via the coronary sinus on functional mitral regurgitation (MR) in patients with pacing-induced cardiomyopathy are scarce.

METHODS

This analysis of the UPGRADE study, an investigator-initiated randomized controlled trial to evaluate the effect of conventional CRT on central sleep apnea, evaluated the significance of CRT on MR in all included patients. Differences in all-cause mortality were assessed in patients with significant MR during long-term follow-up.

RESULTS

Overall, 54 patients were included in the trial. MR was found in the majority of patients [mild: n = 30 (55.6%), moderate: n = 15 (27.8%), severe: n = 6 (11.1%)], while "none/trace" MR was observed in only three (5.6%) patients. CRT was associated with a significant reduction in MR ["none/trace": n = 5 (9.6%), mild: n = 37 (71.2%), moderate: n = 6 (11.5%), severe: n = 4 (7.7%); p = 0.035)] after 3-5 months, with all patients either having an improvement in MR grading or it remaining unchanged. Notably, only two patients with severe MR improved to either a mild or moderate level. CRT upgrading was linked to a significant amelioration of vena contracta width [2 mm (1.0-4.3) at baseline versus 2 mm (1.0-3.0) post-CRT; r = 0.73, 95% CI 0.53-0.85, p < 0.001]. The presence of significant MR at baseline was associated with impaired survival during long-term follow-up [MR < 2: n = 14 (42.4%), MR ≥ 2: n = 19 (90.5%); hazard ratio 0.25 (95% CI 0.12-0.54); log rank p < 0.001].

CONCLUSION

Conventional CRT upgrading in patients with pacing-induced cardiomyopathy was associated with significant improvement in MR grading. The presence of moderate or severe MR at baseline was associated with impaired outcomes during long-term follow-up, suggesting that these patients represent a high-risk cohort.