Active myocardial inflammation may be a powerful predictor of recurrent ventricular tachycardia (VT) following catheter ablation, according to a study published Sept. 28 in the Journal of the American College of Cardiology.

Giovanni Peretto, MD, et al., assessed 125 consecutive patients with myocarditis undergoing VT ablation to describe results and identify factors associated with arrhythmia recurrences. Before ablation, disease stage was evaluated to identify active vs. previous myocarditis, and the primary study endpoint was the assessment of VT recurrences by 12-month follow-up.

Results showed that all patients had history of myocarditis diagnosed by endomyocardial biopsy (59%) and/or CMR (90%), as well multiple episodes of drug-refractory VTs.

The authors found that multimodal pre-procedural staging identified 47 patients with active myocarditis (38%) and 78 patients with previous myocarditis (62%). In addition, all patients showed low-voltage areas at electroanatomical map (97% epicardial or endoepicardial); of them, 25 (20%) had wide borderzone. 

Furthermore, results showed that VT recurrences were documented in 25 patients (20%) by 12 months, and in 43 (34%) by last follow-up. At multivariable analysis, active myocarditis stage was found to be the only predictor of VT recurrences by 12 months, whereas both active myocarditis stage and wide borderzone were associated with arrhythmia recurrences anytime during follow-up.

No VT episodes were found after redo ablation was performed in 23 patients during previous myocarditis stage.

"Further research is necessary to confirm our findings and describe the morphological and functional characteristics of the borderzone," the authors conclude. "As mapping and ablation techniques are in constant evolution, future studies are needed to assess the role of VT mapping-guided ablation, as compared with a substrate-based approach."

In a related editorial comment, Kalyanam Shivkumar, MD, PhD, FACC, and Duc H. Do, MD, FACC, note that "multicenter studies to capture a larger and more generalizable patient sample are necessary to better understand the utility of different diagnostic algorithms and treatment modalities." However, they add that, "unless a concerted effort is made to look for inflammation, it will remain overlooked and underrecognized, to the detriment of these patients. Thus, it is wise to look carefully at the heart before choosing an ablation catheter for interventions."

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Myocarditis, Tachycardia, Ventricular, Catheter Ablation, Arrhythmias, Cardiac, Inflammation, Biopsy, Algorithms

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