Cardiac resynchronization therapy in mild heart failure: a review of the REVERSE and MADIT-CRT trials.

Cardiac resynchronization therapy has become part of the treatment strategy for advanced, symptomatic heart failure, but newly published trials show that more patients than previously realized may benefit from this therapy, including those with mild heart failure symptoms. The REVERSE and MADIT-CRT trials showed that cardiac resynchronization therapy reduces risk of hospitalization for heart failure and leads to beneficial reverse remodeling of the left ventricle in mild heart failure, especially in patients with prolonged QRS complexes. Ongoing studies aim to expand the indications for this therapy even further, including in patients with normal ejection fractions and a need for frequent ventricular pacing. The current body of evidence favors cardiac resynchronization therapy in patients with a depressed ejection fraction and prolonged QRS, even with minimal or no heart failure symptoms.

Randomized comparison of defibrillation thresholds from the right ventricular apex and outflow tract.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) leads are traditionally placed in the right ventricular apex (RVA), in part because this is considered the preferred vector for minimizing defibrillation threshold (DFT). However, if adequate DFT safety margins are attainable, ICD leads placed in the right ventricular outflow tract (RVOT) might confer advantages if frequent ventricular pacing is anticipated. OBJECTIVE: The purpose of this study was to compare RVA with RVOT transvenous ICD lead position on DFT. METHODS: This was a prospective, randomized, crossover study of RVA versus RVOT DFT in 33 patients undergoing left pectoral ICD placement. A binary search algorithm was used to measure DFT, with initial lead position tested in randomized order. The relationship between RVOT position and DFT was assessed by evaluation of the distance between RVA and RVOT. RESULTS: The study population had a mean age of 59 ± 12 years and ejection fraction of 33% ± 14%. Mean DFT in the RVA was 9.8 ± 7.3 J versus 10.8 ± 7.2 J in the RVOT (P = .53), with no correlation between RVOT location and DFT. CONCLUSION: The study found no evidence that ICD lead placement in the RVOT is associated with significantly higher DFT than lead placement in the RVA.