Abstract
INTRODUCTION: The clinical, electrocardiographic and echocardiographic features and long-term outcome of patients with tachycardia-induced cardiomyopathy (TIC) have not been well described in the past. METHODS: A retrospective study was performed at our institution of patients with a diagnosis of TIC. RESULTS: Thirty-three patients with pure TIC and 12 patients with impure TIC were identified. Compared to patients with dilated cardiomyopathy (DCMO), pure TIC patients were less symptomatic, as judged by NYHA class (p = 0.02), they had fewer clinical signs of heart failure (p = 0.007) and were more likely to report palpitations (p = 0.007) at presentation. Electrocardiographically, pure TIC patients had fewer Q waves (p = 0.002), less left ventricular hypertrophy (LVH) (p = 0.004) and repolarisation abnormalities (p = 0.048), and shorter QRS durations (p = 0.024). Echocardiographically, pure TIC patients had significantly smaller left ventricular internal diameter in diastole (LVIDd) ( p < 0.001), ventricular internal diameter in systole (LVIDs) (p = 0.001) and left atrial dimensions (p = 0.048) at presentation compared to DCMO patients. Patients with pure TIC had a trend towards increased residual LVIDd dimensions compared to a control group with normal echocardiograms, indicating a persistence of adverse LV remodelling late after control of the causative tachycardia (p = 0.06). Recurrent tachycardia occurred in three patients, which resulted in a precipitous decline in left ventricular ejection fraction (LVEF). CONCLUSIONS: This study is the first to compare features of pure and impure TIC. Patients with pure TIC had shorter QRS durations, fewer Q waves, and less LVH and repolarisation abnormalities at presentation compared to DCMO patients. TIC patients tended to have smaller LVIDd dimensions at presentation and have persistence of adverse LV remodelling, as characterised by persistent enlargement of LVIDd dimensions, at late follow up.