Compare characteristics and outcomes of patients receiving implantable cardioverter defibrillators (ICDs) for primary vs secondary cardiac arrest prevention.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.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).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.
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.
Key Teaching Points•The decision to replace or downgrade a cardiac resynchronization therapy–defibrillator (CRT-D) system upon reaching battery depletion status carries important considerations, especially in patients who have benefited from cardiac resynchronization therapy but have not experienced ventricular tachyarrhythmias.•There is currently no commercially available DF4 to DF1 adapter, which limits the ability to downgrade a CRT-D to a cardiac resynchronization therapy–pacemaker (CRT-P) system, which uses a DF4 implantable cardioverter–defibrillator (ICD) lead.•We present a case report of connecting a DF4 ICD lead to the quadripolar left ventricular (LV) port of a CRT-P and the bipolar LV lead to the right ventricular pacing port in a Boston Scientific system.•This approach is limited to bipolar and unipolar LV leads and does not apply to quadripolar leads. •The decision to replace or downgrade a cardiac resynchronization therapy–defibrillator (CRT-D) system upon reaching battery depletion status carries important considerations, especially in patients who have benefited from cardiac resynchronization therapy but have not experienced ventricular tachyarrhythmias.•There is currently no commercially available DF4 to DF1 adapter, which limits the ability to downgrade a CRT-D to a cardiac resynchronization therapy–pacemaker (CRT-P) system, which uses a DF4 implantable cardioverter–defibrillator (ICD) lead.•We present a case report of connecting a DF4 ICD lead to the quadripolar left ventricular (LV) port of a CRT-P and the bipolar LV lead to the right ventricular pacing port in a Boston Scientific system.•This approach is limited to bipolar and unipolar LV leads and does not apply to quadripolar leads.
Importance The emergence of novel programming guidelines that reduce premature and inappropriate therapies along with the availability of new implantable cardioverter-defibrillator (ICD) technologies lacking traditional endocardial antitachycardia pacing (ATP) capabilities requires the reevaluation of ATP as a first strategy in terminating fast ventricular tachycardias (VTs) in primary prevention ICD recipients. Objective To assess the role of ATP in terminating fast VTs in primary prevention ICD recipients with contemporary programming. Design, Setting, and Participants This global, prospective, double-blind, randomized clinical trial had an equivalence design with a relative margin of 35%. Superiority tests were performed at interim analyses and the final analysis if equivalence was not proven. Patients were enrolled between September 2016 and April 2021 at 134 sites in 8 countries, with the last date of follow-up on July 6, 2023. Patients were required to have an indication for a primary prevention ICD, including left ventricular ejection fraction less than or equal to 35%. Interventions Patients were randomized in a 1:1 ratio to receive ATP plus shock vs shock only. Main Outcomes and Measures The primary end point was time to first all-cause shock. Secondary end points included time to first appropriate shock, time to first inappropriate shock, all-cause mortality, and the composite of time to first all-cause shock plus all-cause mortality. Results A total of 2595 patients were randomized (mean age, 63.9 years; 22.4% were females). At a mean follow-up of 38 months, first all-cause shock occurred in 129 participants in the ATP plus shock group and 178 participants in the shock only group. The hazard ratio (HR) for the primary end point was 0.72 (95.9% CI, 0.57-0.92), with P = .005 for superiority of the ATP plus shock group over the shock only group. During follow-up in an intention-to-treat analysis, the total shock burden per 100 patient-years was not statistically different, at 12.3 and 14.9, respectively ( P = .70). Conclusions and Relevance The use of a single burst of ATP prior to shock in primary prevention ICD recipients with modern ICD detection programming prolonged the time to first all-cause ICD shock. Trial Registration ClinicalTrials.gov Identifier: NCT02923726
