Right Ventricular versus Biventricular Antitachycardia Pacing in the Termination of Ventricular Tachyarrhythmia in Patients Receiving Cardiac Resynchronization Therapy: The ADVANCE CRT-D Trial

BIVentricular versus right ventricular antitachycardia pacing to terminate ventricular tachyarrhythmias in patients receiving cardiac resynchronization therapy: the ADVANCE CRT-D Trial

BACKGROUND

This multicenter, prospective, randomized, controlled, parallel trial compares the efficacy of biventricular (BIV) versus right ventricular (RV) antitachycardia pacing (ATP) in terminating all kinds of ventricular tachycardia (VT).

METHODS

Five hundred twenty-six patients implanted with a cardiac resynchronization therapy defibrillator (CRT-D) device were enrolled and randomized 1:1 to either BIV (266) or RV (260) ATP (single burst 8 pulse, 88% coupling interval) and were followed up for 12 months.

RESULTS

During 12 months' follow-up, 1,077 ventricular episodes in 180 patients were detected and classified: 634 true VTs divided into 69 ventricular fibrillation (VF) (11%), 202 fast ventricular tachycardia (FVT) (32%), and 363 VT (57%). A comparable first ATP efficacy (BIV 65% vs RV 68%, P = .59) was observed in FVT + VT, in VT zone (BIV 62% vs RV 71%, P = .25), and in FVT zone (BIV 71% vs RV 61%, P = .34). A trend toward lower accelerations during ATP applied to FVT was observed in the BIV group (3.5% BIV vs 10.2% RV, P = .163). No syncope/presyncope occurred during ATP for FVT in the BIV group versus 4 events (3.2%) in the RV group (P = .016). biventricular ATP was more effective in treating FVT in coronary artery disease (CAD) patients (P = .032), whereas both modalities presented similar efficacy in patients with non-CAD etiology (P = .549).

CONCLUSIONS

Antitachycardia pacing is effective in patients implanted with a CRT-D device. No significant differences in efficacy emerged between BIV- and RV-delivered ATP in the general population, whereas BIV ATP seems to present a safer profile in ischemic patients.

Avoid delivering therapies for nonsustained fast ventricular tachyarrhythmia in patients with implantable cardioverter/defibrillator: the ADVANCE III Trial

INTRODUCTION

The purpose of this investigation is to evaluate whether a prolonged detection interval for life threatening ventricular tachyarrhythmia (VT) is able to reduce therapies (Rx) delivered by an implantable cardioverter/defibrillator (ICD). Until now, only the PREPARE trial demonstrated a reduction of ICD Rx in a cohort of primary prevention patients.

METHODS AND RESULTS

The ADVANCE III study is a prospective, randomized, parallel trial with 2 arms evaluating different intervals to detect (NID), i.e., 18/24 (as currently used) versus 30/40. The primary endpoint is to demonstrate a 20% reduction of ICD Rx (antitachycardia pacing or shocks) delivered to terminate spontaneous VT with a cycle length < or =320 ms in patients with Class I-IIA indication for ICD therapy, regardless of cardiac resynchronization capabilities. The worldwide investigation started in spring 2008 and is expected to be finished in 2011.

CONCLUSIONS

The ADVANCE III trial is the first randomized investigation evaluating the reduction of ICD Rx for fast VT due to a prolongation of NID in a general ICD patient cohort.

Cardiac Resynchronization Therapy: A Review of Proarrhythmic and Antiarrhythmic Mechanisms

Available evidence supports the hypothesis that cardiac resynchronization therapy (CRT) results in favorable structural as well as electrical remodeling. Electrical remodeling seems to be related, to a large extent, to structural remodeling, usually referred to as reverse remodeling of left ventricular (LV) dysfunction. This can lead to amelioration of the arrhythmogenic substrate associated with depressed LV systolic function and heart failure. However, a direct electrophysiological effect due to favorable remodeling of repolarization with reduction of the dispersion of repolarization cannot be ruled out. On the other hand, in a small subgroup of patients, CRT could increase the dispersion of repolarization and induce malignant ventricular tachyarrhythmias. Clinical trials have consistently shown improved outcome with CRT-defibrillators (CRT-D) and more trials have demonstrated the benefits of the defibrillator in the population with depressed LV function. However, some physicians argue that implanting the less expensive and less complicated CRT-pacemaker (CRT-P) may be appropriate in certain groups of patients. Before this position is accepted, it is imperative that criteria for the selection of this group of patients with presumably low risk for sudden arrhythmic death as well as the proarrhythmic effect of CRT be clearly defined.

Interactions between paced wavefronts and monomorphic ventricular tachycardia: implications for antitachycardia pacing

OBJECTIVES

Interactions between paced wavefronts and monomorphic ventricular tachycardia (VT) dictate antitachycardia pacing outcomes. We used optical mapping to assess those interactions during single and dual site pacing of rabbit ventricular epicardium.

METHODS AND RESULTS

Monomorphic VTs were initiated in six isolated rabbit hearts that were endocardially cryoablated to limit viable tissue to visible epicardium and establish apical tissue as the anatomic anchor. Preparations were optically mapped during single (n = 39) and dual (n = 43) site pacing at 50%-90% of VT cycle length (CL) with eight pulses per trial. Overall, we found six pulses that abruptly terminated VT. This occurred because the VT wavefront collided with the antidromic portion of the paced wavefront and the orthodromic portion of paced wavefront blocked in the VT's refractory region. When effective, dual site pacing that captured tissue at both leads simultaneously terminated the VT immediately, while single site pacing or dual site pacing that captured tissue at only one lead terminated the VT after resetting advanced the orthodromic wavefront. We found 12 pulses that induced polymorphic VT, with 11 of those pulses occurring during capture at only one lead. Expansion of the combined antidromic-VT wavefront around one or both ends of the arc of conduction block formed by the interaction of the orthodromic wavefront with the VT's refractory region initiated functional reentry. Six of these polymorphic VTs were nonsustained because the underlying wavefronts self-terminated. The wavefronts did persist for 4.2 +/- 3.5 cycles before self-terminating in these trials, and the post-pacing cycles presented a 146% increase in CL variability, compared with the variability prior to pacing. These temporal characteristics are similar to those of delayed termination in patients with ICDs.

CONCLUSIONS

The main difference between pulses that terminated abruptly and pulses that induced polymorphic VT was the effective separation of the antidromic and orthodromic portions of the paced wavefront from one another.