For stable clinical ventricular tachycardias, a substrate based ablation approach is more effective than conventional ablation preventing recurrences from any ventricular tachycardias in patients with ischaemic cardiomyopathy, according to results of the VISTA study, which is the first randomised trial performed in this area.
Data from the VISTA (Ablation of clinical stable ventricular tachycardia versus substrate base ablation on long-term freedom from any ventricular tachycardia) open-label, randomised, multicentre study were presented by Luigi Di Biase (Texas Cardiac Arrhythmia Institute at St David’s Medical Center, Austin, USA and Albert Einstein College of Medicine, at Montefiore Hospital, New York, USA) at a Late-breaking trial session at HRS 2014.
Di Biase highlighted that non-randomised studies have previously suggested that substrate ablation is superior to conventional ablation of clinical stable ventricular tachycardia achieving freedom from any ventricular tachycardia at follow-up; however, randomised data were lacking.
Di Biase told Cardiac Rhythm News: “In the VISTA study we found that the substrate-based ablation approach allows performing ventricular tachycardia ablation while in sinus rhythm, therefore the procedure might be a bit easier for the physician and for the patient and with better success rates.” He said that 84.5% patients treated with the substrate based ablation approach were free from any clinical ventricular tachycardia at 12 months follow-up compared to 51.7% patients treated with the conventional approach.
Between April 2009 and July 2013, 118 patients with symptomatic, drug refractory, haemodinamically stable clinical ventricular tachycardias were enrolled at seven centres in the USA and Europe. They were randomly assigned (1:1 ratio) to conventional ventricular tachycardia ablation (n=60, mean age 65±12 years) and to substrate ablation (n=58, mean age 67±9 years). Baseline characteristics were not different between both groups and all patients were followed up for at least 12 months, with interrogations and office visits every three months, noted Di Biase.
He explained that the ablation strategy for the conventional approach included short linear ablation lesions placed across the ventricular tachycardia isthmus to terminate clinical ventricular tachycardia. It also included activation mapping, entrainment manoeuvres and pace mapping. For the substrate ablation approach, he said, lesions targeted the entire scar area as defined by 3D mapping to target all abnormal electrograms.
In both approaches, epicardial mapping and ablation were considered in case of inducible clinical ventricular tachycardias after endocardial ablation. Radiofrequency ablation with open irrigated catheter was used. Procedural and fluoroscopy times were not statistically different between groups, although a trend towards longer procedures was noted in the conventional ablation arm.
Results
Overall, “a substrate ablation approach may improve the success rate and might reduce overall mortality in patients with ventricular tachycardia,” said Di Biase. He told delegates that no patients were lost to follow-up. More patients were on antiarrhythmic drugs after conventional ablation (58%) than those treated with the substrate based ablation approach (12%).
Di Biase noted that combined incidence of re-hospitalisation and mortality was “significantly higher” in the conventional group approach than in the substrate ablation approach (46.7% vs. 20.7%, p=0.003, respectively).
Conventional ventricular tachycardia ablation, after Cox multivariate analysis, was associated with three times more recurrence compared to substrate ablation (hazard ratio 3.1, p=0.01), said Di Biase.
Regarding complications, he commented, one arteriovenous fistula and two pericardial effusions occurred in the conventional group and three pericardial effusions were reported in the substrate ablation group. All effusions were treated conservatively.
Di Biase suggested the need for further randomised studies to confirm these results.
