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WASHINGTON -- Researchers made a strong case that earlier was better when it comes to catheter ablation of ventricular tachycardias (VTs) in people with implantable cardiac defibrillators (ICDs).

After a first ICD shock, 23 patients with ischemic or non-ischemic cardiomyopathy soon underwent radiofrequency VT ablation and ended up with 4% incidence of worsening heart failure (HF) hospitalizations or all-cause mortality over 2-year follow-up. This was substantially lower than the 42% event rate for the 24 controls who didn't receive ablation unless they suffered an arrhythmic storm (HR 0.11, 95% CI 0.01-0.85), according to Paolo Della Bella, MD, of San Raffaele Hospital in Milan, Italy.

In particular in the PARTITA trial, the reduction was driven by the difference in deaths (0% vs 33%, P=0.004) rather than worsening HF hospitalization (4% vs 17%, P=0.159), he said in a presentation at the American College of Cardiology (ACC) meeting. The trial results were simultaneously published in .

Early ablation also resulted in fewer recurrent VT episodes treated with ICD shocks (9% vs 42%, P=0.039).

Showing benefits to early VT ablation was an "extraordinary" result, Della Bella stated.

"Although no complications were observed in our study patients, it is common knowledge that VT ablation is a complex procedure that can be associated with complications and risks. From this perspective, the time selection proposed in our study provides an efficient indication to treatment for patients with an active arrhythmia pattern, while avoiding potentially unnecessary prophylactic VT ablation procedures," the group wrote.

Notably, the trial had been stopped early after an interim analysis suggested >99% Bayesian posterior probability of superiority for early treatment over standard therapy.

Della Bella reported that anti-tachycardia pacing (ATP) predicted the occurrence of appropriate ICD shocks in the study.

He told ACC discussant Eugene Chung, MD, of the University of Michigan Health in Ann Arbor, that he was in favor of a pre-shock approach to ablation, and that more work is now needed in finding if a "magic threshold" exists for the number ATP treatments that would warrant ablation.

was conducted at 16 sites in Italy and several other countries in Europe.

The trial had 517 patients with ischemic or non-ischemic dilated cardiomyopathy and a primary or secondary prevention indication for an ICD. They were followed through home monitoring over the course of the study. Amiodarone use was not allowed unless there was a documented atrial tachyarrhythmia.

During the study's observation phase, 30% of participants had VTs, 11% of whom received an appropriate ICD shock at a median 2.4 years. After being shocked, 84% agreed to be randomized in the subsequent phase of the trial.

Between early ablation and standard treatment groups, there was no difference in the recurrence of any VTs (30% vs 50%, P=0.434).

Limitations of PARTITA include lower-than-expected ICD shock rates and the small number of catheter ablation procedures.

Nonetheless, it is one of the few prospective studies of VT ablation, Chung said.

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