The effect of ICD programming on inappropriate and appropriate ICD Therapies in ischemic and nonischemic cardiomyopathy: the MADIT-RIT trial.

INTRODUCTION: The MADIT-RIT trial demonstrated reduction of inappropriate and appropriate ICD therapies and mortality by high-rate cut-off and 60-second-delayed VT therapy ICD programming in patients with a primary prophylactic ICD indication. The aim of this analysis was to study effects of MADIT-RIT ICD programming in patients with ischemic and nonischemic cardiomyopathy. METHODS AND RESULTS: First and total occurrences of both inappropriate and appropriate ICD therapies were analyzed by multivariate Cox models in 791 (53%) patients with ischemic and 707 (47%) patients with nonischemic cardiomyopathy. Patients with ischemic and nonischemic cardiomyopathy had similar incidence of first inappropriate (9% and 11%, P = 0.21) and first appropriate ICD therapy (11.6% and 14.1%, P = 0.15). Patients with ischemic cardiomyopathy had higher mortality rate (6.1% vs. 3.3%, P = 0.01). MADIT-RIT high-rate cut-off (arm B) and delayed VT therapy ICD programming (arm C) compared with conventional (arm A) ICD programming were associated with a significant risk reduction of first inappropriate and appropriate ICD therapy in patients with ischemic and nonischemic cardiomyopathy (HR range 0.11-0.34, P < 0.001 for all comparisons). Occurrence of total inappropriate and appropriate ICD therapies was significantly reduced by high-rate cut-off ICD programming and delayed VT therapy ICD programming in both ischemic and nonischemic cardiomyopathy patients. CONCLUSION: High-rate cut-off and delayed VT therapy ICD programming are associated with significant reduction in first and total inappropriate and appropriate ICD therapy in patients with ischemic and nonischemic cardiomyopathy.

Improvement in hemodynamic response using a quadripolar LV lead.

BACKGROUND: The Quartet quadripolar lead (St. Jude Medical Inc., St. Paul, MN, USA) offers 10 different left ventricle pacing configurations that may further influence hemodynamic parameters compared to traditional bipolar pacing configurations. The purpose of this study was to evaluate whether pacing from additional quadripolar lead vectors could enhance cardiac output (CO). METHODS: For each patient, CO was measured in "no-pacing" and in all the 10 configurations available, within 7 days of implantation of the device. Tip-ring, tip-right ventricular coil (RVC), and ring-RVC vectors were considered as traditional vectors. The seven additional configurations available in the quadripolar lead were considered as nontraditional vectors. CO was measured by ECHO. The best configuration was defined as the one presenting the highest CO measurement within configurations, which have a capture threshold <3 V and a safety margin between the capture and the phrenic nerve stimulation thresholds. RESULTS: Fifty-one standard cardiac resynchronization therapy patients were enrolled. The mean of each patient's best CO obtained with traditional vectors was higher than the baseline nonpaced CO (4.16 L/min vs 3.64 L/min). The mean of each patient's best CO, including all 10 available configurations, was also higher than the baseline nonpaced CO (4.33 L/min vs 3.64 L/min). In addition, the mean of each patient's best CO obtained with the best configuration available through a quadripolar lead was better than the mean of each patient's best CO obtained with a traditional configuration. In 53% of patients, the best CO was obtained with a nontraditional vector unique to the quadripolar lead. CONCLUSIONS: A quadripolar lead offers multiple additional pacing options to increase CO acutely compared to conventional bipolar leads.