Effectiveness of VF induction with DC fibber versus conventional induction methods in patients on chronic amiodarone therapy.

BACKGROUND: Amiodarone therapy, especially chronic, can result in difficult ventricular fibrillation (VF) inductions during implantable cardioverter defibrillator (ICD) testing. The efficacy of various VF induction methods on patients treated with amiodarone has not been well described. This prospective analysis evaluated the impact of direct current (DC) fibber, burst fibber, and synchronized T-wave shock VF induction methods. METHODS: Data were collected from one study and two enrolling centers totaling 14 ICD patients (92.9 % male, age 64.3 years (range 23.6-81.2)). A minimum of two successful VF inductions from each patient were required to be included in the study analysis. Each VF induction method was attempted in each patient. Non-sustained VF resulting in an aborted shock was considered an induction failure. All 14 patients were on chronic amiodarone therapy. RESULTS: From a total of 42 attempted inductions, 25 (59.5 %) were successful at inducing VF. The success rates of effective induction of VF during the first attempt using DC, burst, and Shock-on-T are 100, 50, and 28.6 %, respectively. DC fibber had significantly higher VF induction rates than Shock-on-T (p = 0.004) or burst fibber (p = 0.02). There was no difference between Shock-on-T and burst fibber (p = 0.45). CONCLUSION: The success rate of VF induction using DC fibber method is significantly higher than either Shock-on-T or burst fibber induction methods for patients on chronic amiodarone therapy. This may facilitate defibrillation threshold testing in such patients.

Rationale and design of a randomized clinical trial to assess the safety and efficacy of frequent optimization of cardiac resynchronization therapy: the Frequent Optimization Study Using the QuickOpt Method (FREEDOM) trial.

OBJECTIVE: The aim of the study was to describe the rationale, design, and end points of a randomized, double-blind, controlled trial evaluating frequent systematic optimization of atrioventricular (AV) and interventricular (VV) delays in patients receiving cardiac resynchronization therapy (CRT). METHODS: One thousand five hundred eighty heart failure patients, with standard clinical indications for CRT, were enrolled at 178 sites in 16 countries. Within 2 weeks after implantation of a CRT system capable of using a new device-based algorithm for AV and VV optimization, patients were randomly assigned to frequent optimization arm versus empiric device programming or any other non-device-based method of CRT optimization (standard of care arm). In patients in the frequent optimization arm, the AV and VV delays were calculated, reevaluated, and, if necessary, reprogrammed every 3 months. In patients in the standard of care arm, device programming was left to the implanting physician's discretion and remained unchanged throughout the trial unless mandated by a change in clinical status. The primary end point of the trial is the heart failure clinical composite, which classifies patients as worsened, unchanged, or improved based on prespecified definitions. Secondary end points include hospitalizations for cardiovascular reasons and all-cause mortality. End points are adjudicated by an independent committee blinded to study assignment. CONCLUSIONS: The FREEDOM trial, expected to conclude late in 2009, will determine whether frequent optimization of CRT, using a new device-based algorithm, is associated with better clinical outcomes than current standard of care. In addition to improving patient care, this approach might alleviate the workload and economic burden imposed by current approaches to optimization of CRT devices.

Optimization of AV and VV delays in the real-world CRT patient population: an international survey on current clinical practice.

BACKGROUND: Cardiac resynchronization therapy (CRT) is an effective treatment for patients suffering from advanced heart failure and electrical dyssynchrony. Limited data suggest that patients may benefit from routine optimization of the atrioventricular (AV) and interventricular (VV) delays; however, there is scarce information available on how and when optimization should be performed. OBJECTIVE: The objective of this survey was to characterize the current international standard of care for optimization of the AV and VV delays in CRT devices recipients. METHODS: Centers participating in the Frequent Optimization Survey Using the QuickOpt Method (FREEDOM) study completed surveys probing into their optimization of AV and VV delays procedures. Probes focused on the methods used to optimizing the delays, visits at which optimization of the delays was performed, percentage of patients that underwent optimization, and factors that limited centers from optimizing the CRT systems. RESULTS: Few of the 118 investigators from 16 countries who responded to the survey routinely optimized the delays in all patients. At follow-up visits and during hospitalizations, a trend was observed to optimize the delays more often in nonresponders than in responders to CRT. Standard echocardiography was the most common method of optimization. Time availability and lack of qualified staff were the main factors limiting the optimization of CRT systems. CONCLUSIONS: In real-world practice, AV and VV optimization was not performed in a high proportion of patients. A less time-consuming and easier optimization method might enable a more systematic optimization of the AV and VV delays at routine follow-up visits in all recipients of CRT systems.