Prevalence of ongoing myocardial inflammation in patients with complex ventricular arrhythmias

P. Bicprendi (München)¹, M. Tydecks (München)², H. Krafft (München)², M.-A. Popa (München)², D.-P. Dischl (München)², N. Erhard (München)³, F. Bahlke (München)³, F. Englert (München)², M. Al Fayad (München)², E. Koops (München)², S. Lengauer (München)², M. Telishevska (München)², G. Heßling (München)⁴, I. Deisenhofer (München)², T. Reiter (München)^2
1TUM Universitätsklinikum - Deutsches Herzzentrum München Elektrophysiologie München, Deutschland; ²Deutsches Herzzentrum München Elektrophysiologie München, Deutschland; ³Deutsches Herzzentrum München Klinik für Herz- und Kreislauferkrankungen München, Deutschland; ⁴Deutsches Herzzentrum München Klinik für Herz- und Kreislauferkrankungen, Abteilung der Elektrophysiologie München, Deutschland

Background
Not all patients with an inflammatory myopericardial syndrome (IMPS) present with typical infarct like symptoms or newly developed heart failure, but rather with arrhythmia driven by the ongoing inflammation. In these patients, the established non-invasive diagnostic pathway including CMR fails to detect the underlying pathology but rather leads towards a symptom orientated treatment approach including ventricular catheter ablation. Intraprocedurally obtained endomyocardial biopsies can detect an underlying inflammation in patients who were clinically not suspected to have an ongoing inflammation. 

Objective
To evaluate the prevalence of chronic lymphocytic myocarditis in patients presenting with complex ventricular arrhythmias and no further clinical findings hinting towards an IMPS.

Method
This single centre retrospective analysis includes patients who were treated with RF ablation therapy due to complex ventricular tachycardia and intraprocedurally underwent a right ventricular EMB for further work up. Collected data included clinical and intraprocedural data, ECG and imaging findings, histopathological findings obtained from EMB and follow up data up to 55 months. 

Results
Among the 70 patients who meet the inclusion criteria, 51 patients (median age 49 y; male 30/51 (58,8%)) with biopsy proven IMPS were identified. Clinical symptoms included recurrent ventricular tachycardia, non-sustained ventricular tachycardia and polymorphic premature ventricular contractions, palpitations (31/51), angina pectoris (10/51), dizziness (22/51), syncope (5/51) and dyspnea (18/51). Non-invasive work-up had remained without pathological findings.
Intracardiac voltage, LAT and pace map identified multiple ablation sites in 36 patients. Biventricular and epicardial ablation was required in 10 patients, and 10 patients were treated unifocally. 
EMB was performed at the end of the ablation procedure, and no EMB associated complications were detected. EMB revealed elevated lymphocyte levels (33/51) in 65%, elevated macrophages in (45/51) 88% as well as signs of myocardial damage with fibrosis in 50 cases. 13 cases demonstrated persistent viral load.
Following the EMB results, immune suppressive therapy was initiated in 9 patients. During follow up, these patients remained arrhythmia-free. In those without additional therapy (42/51), 18 required an additional ablation procedure and 9 remained on antiarrhythmic drug treatment. 

Conclusion
Our data demonstrate a significant prevalence of ongoing myocardial inflammation in patients with ongoing ventricular tachyarrhythmias and no other clinical signs of myocardial inflammation. EMB can safely be performed at the end of the ablation procedure and contributes to detecting the correct diagnosis. This allows modification of therapy towards a tailored approach with additional anti-inflammatory therapy for effective treatment of arrhythmias.