Dual chamber minimal ventricular pacing effective

Late-breaking trial results presented at the Heart Rhythm Society 2007 meeting.

DENVER — The SAVE PACe trial results indicated a 40% reduction in the relative risk of persistent atrial fibrillation with the use of dual chamber minimal ventricular pacing, according to Michael O. Sweeney, MD, from Brigham and Women’s Hospital in Boston.

SAVE PACe compared dual chamber minimal ventricular pacing with conventional dual chamber pacing (DDDR). The Data Monitoring Committee stopped the trial early when its primary endpoint — time to development of persistent AF — was met. It was the first prospective study to demonstrate that prevention of ventricular desynchronization using new dual chamber minimal ventricular pacing algorithms can reduce the risk of developing persistent AF compared with DDDR.

SAVE PACe enrolled 1,065 patients (51% women) with sinus node dysfunction, intact AV conduction, and normal QRS duration. Patients were randomized to DDDR or to the new dual chamber pacing that uses new algorithms (Search AV and MVP) that were designed to prioritize intrinsic AV conduction, preserve ventricular conduction and prevent ventricular desynchronization.

Sixty-eight patients in the DDDR group developed persistent AF vs. 42 patients in the dual chamber minimal ventricular pacing group. Patients in the new dual chamber pacing group also had a lower risk of invasive ablative procedures and hospitalizations for HF, and less ventricular pacing, Sweeney said.

CONVERT study

Episodic amiodarone therapy pericardioversion was no more effective than continuous amiodarone therapy for rhythm control in the CONVERT study. Both strategies were effective but more adverse events occurred in the episodic therapy group, according to Isabelle C. Van Gelder, MD, of the University Hospital Maastricht, the Netherlands.

Investigators enrolled 206 patients with recurrent AF. Participants were given a 600-mg loading dose of amiodarone daily for four weeks, followed by 200 mg daily. Those randomized to the episodic group discontinued amiodarone treatment one month postcardioversion and then restarted the therapy pericardioversion if AF recurred. Patients in the continuous group remained on amiodarone therapy.

No significant differences occurred between the two groups in sinus rhythm control at the median follow-up of 1.8 years; the number of amiodarone-related events was comparable. There were more recurrences of AF and CV in the episodic treatment group and more disease-related events, including hospitalization for HF. Quality of life was similar.

DAVID II and PREPARE

Atrial pacing at 70 bpm (AAI-70) was safe but was no more effective than standby right ventricular pacing at 40 bpm (VVI-40) in the DAVID II trial, reported by Bruce L. Wilkoff, MD, from The Cleveland Clinic.

Six hundred patients were randomized after ICD implantation to one of the two options. Mean follow-up, after periodic follow-up every three months, was 28 months. Wilkoff said investigators found no significant differences between the two groups in death or rehospitalization for new or worsened HF, and no significant differences in AF or syncope.

There was a trend toward earlier time for the first inappropriate shock in the VVI-40 group, but the trend seemed isolated to the secondary prevention patients.

Wilkoff also presented a prospective, nonrandomized, multicenter study, the PREPARE trial, which analyzed aggressively programmed ICD detection and therapy vs. physician-tailored programming in primary prevention patients. The control group was a historical cohort group from both the EMPIRIC trial (non-Bi-V, physician arm only) and the MIRACLE ICD trial (Bi-V) for whom VT/VF detection and therapy programming were not controlled.

Patients in PREPARE were both Bi-V and non-Bi-V patients. Parameters were set to detect rhythms with a rate greater than 182 bpm with duration of at least 30 or 40 ventricular beats. Antitachycardia pacing was programmed for rhythms with a regular cycle length and a rate between 182 bpm and 250 bpm before maximum output shock.

Wilkoff said the incidence of untreated VT and arrhythmic syncope was similar between the PREPARE patients and the control group.