Title: Optimizing Hemodynamics in Heart Failure Patients by Systematic Screening of Left Ventricular Pacing Sites: The Lateral Left Ventricular Wall and the Coronary Sinus Are Rarely the Best Sites
Topic: Arrhythmias
Date Posted: 2/1/2010 5:00:00 PM
Author(s): Derval N, Steendijk P, Gula LJ, et al.
Citation: J Am Coll Cardiol 2010;55:566-575.
Clinical Trial: No
Study Question: What is the optimal left ventricular (LV) pacing site for cardiac resynchronization therapy (CRT)?
Methods: Thirty-five patients (mean age 63 years) with a nonischemic cardiomyopathy (mean ejection fraction 28%) and left bundle branch block underwent hemodynamic measurements during dual-chamber (DDD) pacing from a lateral branch of the coronary sinus (CS) and at 10 prespecified endocardial LV sites. Hemodynamic results at pacing sites were expressed as a percentage variation from the hemodynamics during atrial pacing.
Results: There was a large range in the hemodynamic response to pacing at different sites within individual patients (+19% to +93%), and between different patients (-31% to +93%). None of the 11 pacing sites was consistently associated with the best hemodynamic response to pacing. DDD pacing at the best LV site yielded a better hemodynamic response (+31%) compared to CS pacing (+15%). The CS was the pacing site that yielded the best hemodynamic response in only 9% of patients.
Conclusions: The optimal LV site for CRT is unpredictable, must be identified on an individualized basis by testing, rarely is in the CS, and often is endocardial.
Perspective: The response rate to conventional CRT, with the LV lead in a branch of the CS, has been 60-80%. The results of this study suggest that the response rate to CRT can be improved by identifying the optimal pacing site on an individualized basis. Widespread adaptation of this approach into clinical practice may be hampered by the rigorous and lengthy testing protocol and by the potential problems associated with long-term endocardial LV pacing. Fred Morady, M.D., F.A.C.C.
Title: Comparison of Antiarrhythmic Drug Therapy and Radiofrequency Catheter Ablation in Patients With Paroxysmal Atrial Fibrillation: A Randomized Controlled Trial
Topic: Arrhythmias
Date Posted: 1/28/2010
Author(s): Wilber DJ, Pappone C, Neuzil P, et al., on behalf of the ThermoCool AF Trial Investigators.
Citation: JAMA 2010;303:333-340.
Clinical Trial: yes
Study Question: Is radiofrequency catheter ablation (RFCA) more effective than antiarrhythmic drug therapy (ADT) in patients with paroxysmal atrial fibrillation (PAF)?
Methods: The subjects of this study were 159 patients (mean age 56 years) with symptomatic PAF who had failed to respond to treatment with ≥1 rhythm- or rate-control agent. The patients were randomized to RFCA (n = 103) with an irrigated-tip ablation catheter or ADT (n = 56) with flecainide, propafenone, dofetilide, sotalol, or quinidine. The ablation strategy was a minimum of wide-area pulmonary vein isolation, with additional ablation at the operator’s discretion. Redo RFCA was allowed during a 3-month blanking phase. Efficacy was assessed at clinic visits and with serial transtelephonic monitoring. The 1° endpoint was freedom from symptomatic AF during the 9 months after the blanking period.
Results: A redo ablation procedure was performed in 12.6% of patients in the RFCA group. The 1° endpoint was achieved significantly more often in the RFCA group (66%) than in the ADT group (16%). The rate of major adverse events was higher in the ADT group (8.8%) than in the RFCA group (4.9%).
Conclusions: RFCA is more effective than ADT for preventing PAF in patients who already have not responded to one antiarrhythmic drug.
Perspective: The results confirm that patients with AF who do not respond to one trial of ADT are unlikely to respond to subsequent ADTs, and support the current practice guidelines that consider catheter ablation of AF to be appropriate second-line therapy after failure of initial ADT. The modest efficacy of RFCA (66%) most likely reflects the difficulty in achieving permanent isolation of the pulmonary veins. Fred Morady, M.D., F.A.C.C.
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