**1. Introduction**

Tachycardiomyopathy (TCM) is an important cause of dysfunction of the left ventricle [1]. It is defined as an arrhythmia induced cardiomyopathy in which the impairment of the left ventricle is secondary to rapid and/or asynchronous, irregular myocardial contraction and is partially or completely reversible after treatment of the triggering arrhythmia [2]. Both atrial and ventricular arrhythmias, as well as the premature atrial or ventricular complexes have been noted to cause TCM [1] and no specific heart rate cut-off at which the condition develops has been identified [3].

The first descriptions of TCM were collected by Phillips and Levine in 1949. In their milestone paper, they hypothesized that patients with long-lasting atrial fibrillation could develop heart failure without any other evidence of structural heart disease, and such heart failure could completely disappear after the restoration of the sinus rhythm [4]. TCM is nowadays classified as a non-familial cause of dilated cardiomyopathy, although doubts have been cast on the inclusion of such a disease among those conditions directly affecting the structure and/or function of the heart [5].

TCM is estimated to be under-recognized [3] and the incidence and prevalence of the condition are currently unknown. The mechanisms of TCM and pathways responsible in individual patients are not fully understood [2,6], however it is hypothesised that subclinical ischaemia, abnormalities in energy metabolism, and an overload of calcium and oxidative stress play a role in the pathogenesis of the condition [1]. To this day, two categories of the disease have been described: Arrhythmia-induced TCM, where the arrhythmia is the sole reason for the dysfunction, and arrhythmia-mediated TCM, where the arrhythmia can exacerbate or worsen heart failure (HF) or an underlying heart disease [1]. The former can also be referred to as "pure" TCM and the latter as "impure" TCM [7,8].

The diagnosis of TCM is retrospective and based on the evidence of recovery after appropriate treatment. In fact, although, an arrhythmia is present with a concomitant left ventricular ejection fraction (LVEF) impairment, a cause-effect relationship is not always ascertainable [2]. There is very little data regarding the recurrences and adverse events in patients with TCM in the current available literature.

The aim of this study was to identify the possible predictors of recurrence and long-term morbidity and mortality of pure TCM.
