Abstract 17673: The Effectiveness of Improved ICD Programming by Race: A MADIT-RIT Sub-study

Abstract

Introduction: There are limited data on the risk of inappropriate and appropriate ICD therapy and on the efficacy of different ICD programing strategies as a function of race. Methods: In MADIT-RIT, we evaluated the risk of inappropriate and appropriate ICD therapy by self identified race, and assessed the efficacy of improved ICD programming with either a high rate cut-off VT zone ≥ 200 bpm (Arm B), or long 60 sec delay in the VT zone 170-190 bpm (Arm C), as compared to conventional ICD programming with 2.5 sec delay beginning at 170 bpm (Arm A) among black and white patients. Results: MADIT-RIT enrolled 272 (20%) black and 1119 (80%) white patients. Black patients were younger, more often females, they more often had non-ischemic etiology of cardiomyopathy, a narrower QRS and they were less often implanted with CRT-D. The risk of inappropriate ICD therapy was similar among black and white patients (HR 1.25, 95% CI 0.82-1.93, P=0.30) after adjustment for relevant covariates. High rate cut-off or delayed VT therapy was associated with significant reductions in inappropriate ICD therapy among white patients (Arm B vs. Arm A, HR 0.15, P<0 .0001, Arm C vs. Arm A, HR 0.19, P 0.10). However, delayed VT therapy (Arm C) when compared to Arm A, was associated with greater reduction in appropriate ICD therapy in black patients (HR 0.08, P<0.0001), as compared to white patients (HR 0.27, P<0.0001, P interaction=0.07). There were no appropriate ICD therapies in the 170-200 bpm range in Arm C with delayed VT therapy programming in black patients, and a further reduction in appropriate ICD therapy ≥ 200 bpm (Arm C vs. Arm A, HR=0.16, p<0.001). Conclusion: In MADIT-RIT, there were similar reductions in inappropriate ICD therapy among black and white patients with improved ICD programming. However, black patients derived more benefit from delayed VT zone programming with greater reduction in appropriate ICD therapy compared to whites, due to a higher rate of self-terminating VT events.