Abstract 2134: Transient ST-Segment Elevation on Near Field Right Ventricular Electrogram After ICD Shock Predicts Future Heart Failure Progression
Introduction. In an ICD population, the risk of death due to progressive pump failure without or after prior appropriate ICD therapy is substantial. The purpose of this study was to identify marker of right ventricular (RV) functional impairment after an ICD shock as a predictor of the heart failure progression in ICD patients.
Methods. Near field (NF) right ventricular (RV) electrograms (EGMs) during induced ventricular fibrillation (VF) and 10 sec after rescue ICD shock were extracted from the ICD memory and analyzed in 195 patients (mean age 58 ± 13; 140 male [72%] with ischemic (140 patients, 72%) and non-ischemic (55 patients, 28%) cardiomyopathy and implanted Medtronic ICD for primary (146 patients, 75%) or secondary (49 patients, 25%) prevention of sudden cardiac death. Ventricular fibrillation (VF) was induced with shock-on-T wave protocol during routine defibrillation threshold testing at ICD implantation procedure. Only first successful attempt of VF induction that required single rescue ICD shock was included in the analysis. Digital control EGMs were recorded at rest (mean heart rate 65 ± 15 bpm) during office visit 6 –30 days after ICD implantation. Patients were followed prospectively at least 12 months; death and hospitalizations due to congestive heart failure (CHF) exacerbation served as endpoints. The presence of at least 2 mV ST segment elevation on NF RV EGM during 10 sec after induced VF rescue ICD shock as a marker of RV functional impairment was assessed.
Results. During mean follow-up of 19 ± 8 months, 9 patients died and 26 were hospitalized due to CHF exacerbation. Transient ST-segment elevation (2mV and more) on NF RV EGM after induced VF rescue ICD shock was observed in 34 patients. Of these 34 patients, 6 died and 17 were hospitalized due to CHF during follow-up, 2 underwent heart transplantation. In multivariate risk analysis, patients with ST elevation on NF RV EGM after ICD shock were more likely to die or to be hospitalized (hazard ratio [HR], 6.2; 95% CI, 1.6 to 24.2; P=0.009).
Conclusion. Transient ST-segment elevation on NF RV EGM after induced VF rescue ICD shock at ICD implantation is associated with increased risk of CHF progression, future hospitalizations due to CHF exacerbation and heart pump failure death.