A comparison of outcomes for patients receiving implantable cardioverter defibrillators for primary vs secondary-prevention.

OBJECTIVE: Compare characteristics and outcomes of patients receiving implantable cardioverter defibrillators (ICDs) for primary vs secondary cardiac arrest prevention. METHODS: Patients in this cohort study were identified from a prospectively collected ICD database from June 1999 to August 2003 and divided into groups based on whether they received their ICD for primary or secondary-prevention of cardiac arrest. Patient follow-up continued until August of 2006 and the occurrence of appropriate ICD shocks, inappropriate ICD shocks, and mortality were compared between groups. RESULTS: Of the 437 patients, 80.8% were male, 70.3% had coronary disease, and the mean age was 65.7+/-13.1 years. At baseline, primary-prevention patients had lower left ventricular ejection fraction (LVEF), use of a single chamber device and utilization of beta blockers and antiarrhythmics while having a greater use of biventricular pacing as compared to secondary-prevention patients. Over the first 12 months after implantation, the primary-prevention group was 43.0% less likely to receive an appropriate shock for ventricular arrhythmias (P=0.002) and 34.2% less likely to have an appropriate shock over the entire follow-up period (P=0.018). The incidence of inappropriate ICD shocks over the first 12 months after implantation and over the entire follow-up period was similar between groups (P=0.900 and P=0.217, respectively) as was mortality (P=0.228 and P=0.757, respectively). CONCLUSIONS: Primary-prevention patients are characteristically different in numerous ways from secondary-prevention patients, but despite having a greater risk of experiencing appropriate shocks, exhibit a similar risk of inappropriate shocks and mortality over an average follow-up time exceeding 41 months.

Effects of ischemia on repolarization in patients with single and multivessel coronary disease.

To evaluate if QT dispersion (QTd) may be affected by the number of obstructed coronary arteries (CAs) in patients with acute myocardial infarction (MI) and undergoing angioplasty, and to evaluate if QTd may be affected by ejection function of the heart. The infarct related CA was identified by coronary angiography in 141 patients (97 men, mean age 61.6 +/- 12.9 years) with acute MI undergoing percutaneous angioplasty. Successful reperfusion was defined as TIMI III flow with < 20% residual stenosis. QTd, calculated by subtracting the shortest from the longest QT interval on 12-lead electrocardiograms, was examined immediately before and after angioplasty, at 24 hours, and 3 days after angioplasty. Successful reperfusion was achieved in 98 (69.5%) patients. Prolonged QTd at baseline was found in all patients with ischemia. A trend toward a decrease in QTd was observed immediately after angioplasty and at 24 hours, and a significant decrease at 3 days in patients with successful reperfusion regardless of the number of occluded CAs. There was no change in QTd found in patients with no reperfusion. An increase in QTd was observed in patients with acute ischemia due to single or multivessel disease.