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Long-Term Arrhythmic Risk Assessment in Myocarditis
Study Questions:
What is the long-term arrhythmic risk in patients with myocarditis who received an implantable cardioverter-defibrillator (ICD)?
Methods:
There were 56 patients with biopsy-proven myocarditis who received an ICD for either primary (57%) or secondary prevention (43%). Clinical characteristics, biopsy findings, electrophysiological data from endocardial three-dimensional electroanatomic voltage mapping, and device interrogation data were analyzed in order to detect arrhythmic events over time. Coronary angiography excluded significant coronary artery disease in all patients.
Results:
At a mean follow-up of 74 months, 25 patients (45%) had major ventricular arrhythmias treated by ICD intervention (76% being terminated by ICD shock and 24% by anti-tachyarrhythmia pacing). At multivariable analysis, the presence of sustained ventricular tachycardia on admission (hazard ratio [HR], 13; p = 0.032) and the extension of the areas of low potentials at the bipolar endocardial mapping (HR, 1.19; p = 0.013) were the only independent predictors of appropriate ICD interventions. A cutoff value of 10% of abnormal bipolar area at electroanatomical ventricular mapping discriminated patients with appropriate ICD interventions with a sensitivity of 89% and a specificity of 85%.
Conclusions:
The study shows that the prevalence of life-threatening ventricular arrhythmias in patients with myocarditis receiving an ICD according to current guidelines is high and the arrhythmic risk persists late over time. Electroanatomical ventricular mapping may be a useful tool to identify patients at greater arrhythmic risk.
Perspective:
Ventricular arrhythmias may occur during acute myocarditis, in the setting of chronic myocarditis, and after the complete resolution of inflammation results in myocardial fibrosis. The authors report a substantial rate of appropriate ICD therapy—45% over 75 months, which is higher than patients with dilated nonischemic cardiomyopathy. Interestingly, the patient’s age, histologic findings and whether the ICD indication was for primary or secondary prevention of sudden death did not predict ICD therapy. Sustained ventricular tachycardia at presentation and the extent of scar on electroanatomic map did. Note, all of the patients had a histological diagnosis of lymphocytic myocarditis and none had sarcoidosis, granulomatous, and/or giant cell myocarditis. The optimal risk stratification for sudden cardiac death/ICD implantation in patients with myocarditis continues to be undefined, but the current study suggests that electroanatomical ventricular mapping may be a useful tool warranting future randomized studies.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Atherosclerotic Disease (CAD/PAD), Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Nuclear Imaging
Keywords: Arrhythmias, Cardiac, Biopsy, Cardiomyopathies, Coronary Angiography, Coronary Artery Disease, Death, Sudden, Cardiac, Diagnostic Imaging, Electrophysiology, Defibrillators, Implantable, Heart Failure, Inflammation, Myocarditis, Primary Prevention, Risk Assessment, Secondary Prevention, Tachycardia, Ventricular
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