Introduction:
CRT-D improves cardiac function and quality of life, and decreases HF hospitalization and death for many patients. However, impact on therapy delivered for ventricular arrhythmias is less clear.
Methods:
Device-determined VT and VF episodes with therapy (n = 1835) from CRT-D patients in two trials (CRT RENEWAL & REFLEX; n = 1698) were analyzed in a post hoc fashion. Patients were divided into lifetime biventricular (BiV) pacing percentage quartiles. Zero-inflated Poisson regression models were used to evaluate impact of pacing on VT/VF incidence and frequency, adjusting for baseline covariates including lifetime ATR mode switch percentage.
Results:
Patient characteristics: 69 ± 11 years, 73% male, 68% CAD. Dividing patients in quartiles resulted in the following pacing breakdown: 0–92% (n = 445), 93–97% (n = 445), 98–99% (n = 482), and 100% (n = 326). There were no differences in gender, NYHA, or history of diabetes, MI, CAD or hypertension among the groups. Patients paced 0–92% and 93–97% had similar VT/VF therapy incidence (24.72% vs. 24.27%) and frequency (17.05% vs. 16.00%). Patients paced 98–99% had lower VT/VF therapy incidence (15.15%) than patients paced ≤ 97% (p < 0.001) but similar frequency after adjusting for incidence. Patients paced 100% had similar VT/VF therapy incidence (13.80%) and frequency (6.45%) to patients paced 98–99%. The figure
shows the time to first therapy for VT/VF.
Conclusions:
For CRT-D patients in this analysis, incidence and frequency of therapy delivered for VT/VF is significantly decreased when lifetime BiV pacing percentage is above 97%.
Stability Enhancement of High-speed Rotors on Foil Bearings with the Automatic Mode Switch
