EXERCISE-INDUCED POLYMORPHIC VENTRICULAR ARRHYTHMIAS IN PATIENTS WITH FREQUENT VENTRICULAR COMPLEXES

Aim: Polymorphic ventricular tachycardia (PVT) is a potentially malignant arrhythmia, making it essential to determine the etiology, as different types require varied therapeutic approaches. Our study aimed to determine the etiology of adrenergic-dependent polymorphic ventricular arrhythmias (PVAs) in patients initially undergoing exercise testing due to frequent premature ventricular complexes (PVCs).
Methods: We analyzed 54 patients referred for frequent PVCs (over 30 per hour). All underwent cardiology exams, including exercise tests. Adrenergic-dependent PVAs were identified based on the presence of polymorphic couplets and/or non-sustained PVT during exercise. Patients exhibiting adrenergic-dependent PVT subsequently underwent extensive cardiac assessments, including imaging and genetic testing.
Results: Adrenergic-dependent PVAs were induced in 15 patients. Echocardiography revealed severe mitral regurgitation in one patient, while coronary angiography diagnosed ischemic heart disease in two. Magnetic resonance imaging detected signs of arrhythmogenic cardiomyopathy in three patients. After excluding structural heart disease, four additional patients met the criteria for catecholaminergic polymorphic ventricular tachycardia (CPVT), but mutations in the RYR2 and CASQ2 genes were not found. However, cardiomyopathy gene analysis identified a mutation in the FLNC gene in one patient. Among five patients with confirmed adrenergic dependence and excluded structural heart disease, the etiology remained unclear. Familial occurrence was confirmed in one case.
Conclusion: Adrenergic-dependent PVT represents potentially life-threatening arrhythmia. The differential diagnosis encompasses various conditions, ranging from structural heart disease to channelopathies. Cardiac stress testing can reveal hidden issues in previously asymptomatic patients.