Key Points
- While VT ablation has been associated with improved survival, the most ideal time to undergo VT ablation remains undefined.
- PARTITA was the first clinical trial to randomize patients to early VT ablation versus standard of care after ICD implant for both ischemic and non-ischemic cardiomyopathy.
- Despite its small sample size (n=56), the adaptive Bayesian design of this study predicted a 99.9% predictive probability of success, causing early termination of the trial. Early VT ablation caused a statistically significant reduction in the primary outcome of all-cause mortality or worsening heart failure, compared to standard of care (4.3% vs 41.7%, p=0.01).
- Furthermore, ATP termination of VT was found to be the most significant predictor of subsequent ICD shocks, which suggests that it may be beneficial to perform VT ablation even earlier after ICD implant.
Prior observational studies have shown that freedom from VT recurrence due to VT ablation is associated with improved survival. However, some fundamental questions remain unanswered in the field of electrophysiology: what is the best time to perform VT ablation after ICD implant? Does the prevention of VT impact survival and/or the development of heart failure in randomized settings?
During the 2022 American College of Cardiology Conference, Dr. Paolo Della Bella presented the results from the PARTITA trial – a multicenter, randomized, controlled study that, from 9/2012 to 7/2021, recruited 517 patients after their first ICD implant (whether for ischemic or non-ischemic cardiomyopathy, and both for primary and secondary prevention). After their first appropriate shock, patients (n=56, 11%) were randomized either to prompt intervention via VT ablation (n=23), or standard of care (n=24, i.e. wait for a second shock to consider catheter ablation). Patients had a mean follow-up time of two years, and were monitored via home visit plus annual hospital visits. Despite a lower than expected rate of VT-related shocks, interim analyses based on a Bayesian sequential study design suggested a 99.9% predictive probability of success (i.e. superiority of the early VT ablation arm). Ultimately, patient undergoing early VT ablation showed a statistically significant reduction in the primary outcome of all-cause mortality or worsening heart failure, compared to standard of care (4.3% vs 41.7%, p=0.01), which was driven by a significant reduction in all-cause mortality (0% vs 33.3%, p=0.004). Notably, early VT ablation also caused a significant reduction in recurrent VT with shock (8.7% vs 41.75%, p=0.039). These results were demonstrated both in the intention-to-treat and per-protocol analyses. Lastly, patients who experienced VT requiring termination via ATP were significantly more likely to experience recurrent VT requiring appropriate shocks.
Taken together, results from this study suggest that early intervention via catheter ablation leads to a significant reduction in mortality and morbidity from VT, both in ischemic and non-ischemic cardiomyopathy patients who undergo ICD implant. While this is one of the very first randomized trials in the field of VT ablation, its small sample size calls for larger dedicated studies to provide more definitive conclusions that can change practice. In addition, the finding that ATP termination of VT is the most significant predictor of subsequent ICD shocks suggests that it may be beneficial to perform VT ablation even earlier after ICD implant.