Ineffective cardiac resynchronization pacing is associated with poor outcomes in a nationwide cohort analysis.

Background: Delivery of cardiac resynchronization therapy (CRT) requires left ventricular myocardial capture to achieve clinical benefits.
Objective: We sought to determine whether ineffective pacing affects survival.
Methods: Ineffective ventricular pacing (VP) was defined as the difference between the percentage of delivered CRT (%VP) and the percentage of effective CRT in CRT devices. Using the Optum de-identified electronic health record data set and Medtronic CareLink data warehouse, we identified patients implanted with applicable devices with at least 30 days of follow-up. Kaplan-Meier and Cox proportional hazards models assessed the impact of %VP and % ineffective VP on survival.
Results: Among 7987 patients with 2.1 ± 1.0 years of follow-up, increasing ineffective VP was associated with decreasing survival: the highest observed survival was in the quartile with <0.08% ineffective VP and the lowest survival was in the quartile with >1.47% ineffective VP (85.1% vs 75.7% at 3 years; P < .001). As expected, patients with more than the median %VP of 97.7% had better survival than did patients with <97.7% VP (84.2% vs 77.8%; P < .001). However, patients who had >97.7% VP but >2% ineffective VP had similar survival to patients with <97.7% VP but ≤2% ineffective VP (81.6% vs 79.4%; P = .54). A multivariable Cox proportional hazards model demonstrated that <97.7% VP (adjusted hazard ratio 1.29; 95% confidence interval 1.14-1.46; P < .001) and >2% ineffective VP (hazard ratio 1.35; 95% confidence interval 1.18-1.54; P < .001) were both significantly associated with decreased survival.
Conclusion: Ineffective VP is associated with decreased survival. In addition to maximizing the percentage of delivered CRT pacing, every effort should be made to minimize ineffective VP.
Competing Interests: Disclosures Dr Mittal serves as a consultant to Boston Scientific and Medtronic. Drs Koehler, Stadler, Ghosh, and Klepfer are employees and shareholders of Medtronic. Dr Piccini is supported by R01AG074185 from the National Institutes of Aging. He also receives grants for clinical research from Abbott, the American Heart Association, Boston Scientific, iRhythm, and Philips and serves as a consultant to ABVF, Abbott, AbbVie, Boston Scientific, ElectroPhysiology Frontiers, Kardium, LivaNova, Medtronic, Milestone Pharmaceuticals, Sanofi, Philips, and UpToDate. The rest of the authors report no conflicts of interest.
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