January 5, 2010 (Hamburg, Germany) — Catheter ablation of stable ventricular tachycardia (VT) prior to implanting a defibrillator prolongs the time to recurrence of VT in patients with prior myocardial infarction (MI) and reduced left ventricular ejection fraction (LVEF), a study shows . In addition, the prophylactic use of ablation also resulted in fewer appropriate implantable cardioverter defibrillator (ICD) shocks and fewer cardiac hospital admissions, report investigators.
"On the basis of these data, prophylactic catheter ablation in patients with hemodynamically stable VT, previous myocardial infarction, and reduction in left ventricular function should be strongly considered before implantation of a cardioverter defibrillator, especially in patients with an LVEF of more than 30%," according to lead investigator Dr Karl-Heinz Kuck (Asklepios Klinik, Hamburg, Germany) and colleagues.
The study, known as the Ventricular Tachycardia Ablation in Addition to Implantable Defibrillators in Coronary Heart Disease (VTACH) trial, was published in the January 2, 2010, issue of The Lancet.
These findings, according to an editorial accompanying the study , by Dr William Stevenson and Usha Tedrow (Brigham and Women's Hospital, Boston, MA), support the early use of catheter ablation in patients receiving an ICD and in whom recurrences of VT are likely.
Stevenson and Tedrow write that the VTACH study also provides further evidence supporting "the early use of ablation as an alternative to antiarrhythmic drug therapy for symptomatic recurrent ventricular tachycardia after implantation of an implantable cardioverter defibrillator, provided that the expertise to safely perform the procedure is available."
Reducing the Recurrence of VT
VTACH was a prospective, open, randomized, controlled clinical trial performed in 16 centers in Germany, Switzerland, the Czech Republic, and Denmark. The trial included 110 patients with stable VT, previous MI, and reduced LVEF (<50%), and these patients were randomized to receive catheter ablation before implantation of a defibrillator or an ICD alone.
After a mean follow-up of almost 23 months, the time to recurrence of VT/ventricular fibrillation (VF) was 18.6 months in patients who underwent ablation prior to ICD implantation and 5.9 months in patients who received an ICD alone. At two years, the estimates for survival free from VT were 47% in the ablation arm and 29% in the ICD-only arm, a statistically significant difference when the VT episodes were assessed by the electrogram. The treatment effect with ablation appeared to be larger among those with an LVEF >30%, although this was the result of higher event rates among controls with an LVEF >30%.
Clinical End Points in the Ablation and Control Groups
|24-mo event-free survival estimates||Ablation, n=52 (%)||Control, n=55 (%)||Hazard ratio (95% CI)|
|VT recurrence||46.6||28.8||0.61 (0.37–0.99)|
|Hospital admission for cardiac reasons||67.4||45.4||0.55 (0.30–0.99)|
|VT storm||75.0||69.7||0.73 (0.36–1.50)|
In addition to reducing the recurrence of VT at two years, as well as hospital admissions for cardiac reasons, ablation also significantly reduced the number of appropriate ICD shocks and the number of appropriate ICD interventions and shocks per patient per year.
Overall, there were no procedure-related deaths, although the ablation procedure was stopped in two patients because of transient ischemic events.
VTACH and SMASH-VT
The results of VTACH, according to investigators, are in line with the Substrate Mapping and Ablation in Sinus Rhythm to Halt Ventricular Tachycardia (SMASH-VT) study, a trial that showed radiofrequency ablation guided by electroanatomic mapping of the ventricular arrhythmia substrate in patients with unstable VT, VF, or syncope with inducible VT reduced ICD shocks 73% compared with ICD alone.
Speaking with heartwire , Dr Vivek Reddy (Mount Sinai School of Medicine, New York), who was not affiliated with VTACH but who led the SMASH-VT trial, said that patients with a history of MI and VT are at high risk for sudden death and recurrent VT. The current standard of care, an ICD, doesn't cure VT but only treats it after the episode occurs, and so amiodarone is typically prescribed.
Overall, VTACH differed from SMASH-VT in that it included a very homogenous patient population, including only patients with stable VT. Moreover, VTACH investigators performed ablations in 16 European centers compared with just three in SMASH-VT, and this might explain the smaller benefit observed in VTACH. However, the findings from VTACH are likely more representative of real-world results, Reddy said.
"Still, both of these studies are consistent in that ablation was better than the control therapy of an ICD alone," he told heartwire .
In addition to the reduction in the primary end point, Reddy said the reduction in hospital admissions for cardiac causes, which is an end point used in heart-failure trials, would translate into significant cost savings, although those data are not yet available because VTACH and SMASH-VT did not include any economic analyses. He stressed, however, that despite the relative reduction in VT recurrences, the event rate among patients was still high, with half of all patients ablated still having at least one recurrence of VT.
"Ablation should not be used in lieu of an ICD in these patient groups, that's pretty clear," said Reddy. "They do better with ablation, but there is no doubt that they still require a defibrillator."
In their editorial, Stevenson and Tedrow stressed that many important questions remain, such as whether ablation should be preferred over antiarrhythmic drugs or whether ablation should be offered immediately or performed only if VT recurs after receiving the ICD. Larger studies addressing mortality, heart-failure risk, and quality of life are also still needed, they write.
Reddy said that before ablation prior to defibrillator implantation becomes standard practice, the ablation technique needs to be improved still, especially since the magnitude of benefit observed in the multicenter VTACH trial was less than that observed in the three experienced centers participating in the SMASH-VT trial. Similarly, there needs to be more uniformity in the ablation strategies, he said, as there is not yet one best way to tackle the arrhythmia.
Heartwire from Medscape © 2010 Medscape, LLC
Cite this: VTACH: Ablation Before ICD Reduces Recurrence of Ventricular Tachycardia - Medscape - Jan 05, 2010.