Author`s Reply.

To the Editor,

I thank the journal readers for their interest in our original article entitled “Tp-e interval and Tp-e/QTc ratio as novel surrogate markers for prediction of ventricular arrhythmic events in hypertrophic cardiomyopathy” recently published in The Anatolian Journal of Cardiology 2017 Mar 9. Epub ahead of print (1).

Hypertrophic cardiomyopathy (HCM), a common genetic heart disease characterized by ventricular hypertrophy, impaired ventricular relaxation, and myocardial fibrosis, is significantly associated with a higher risk of fatal ventricular arrhythmic events (2). HCM is a leading cause of sudden cardiac death (SCD) in young adults (3). Current 2014 European Society of Cardiology (ESC) guidelines on the diagnosis and management of HCM recommend a prophylactic implantable cardioverter defibrillator (ICD) therapy for the primary prevention of SCD in high-risk patients based on age, unexplained syncope, family history of SCD, maximum left ventricular wall thickness (LVWT), maximum left ventricular outflow (LVOT) gradient, left atrial size, and non-sustained ventricular tachycardia (NSVT) during 24–48-h Holter monitoring at or prior to evaluation (2, 3). Other than these variables, Kang et al. (4) have recently demonstrated that the presence of a fragmented QRS complex (fQRS) on 12-lead electrocardiography (ECG) is significantly associated with a higher risk of fatal ventricular arrhythmia events (VAEs), including NSVT, VT, and SCD in patients with HCM. Similarly, in our study we observed that prolonged Tp-e interval and increased Tp-e/QTc ratio are independent predictors of VAEs in patients with HCM (1). The Tp-e interval (the interval between the peak and end of the T wave on ECG) is described as an index of total dispersion of ventricular repolarization, and a longer Tp-e interval has been found to be related to arrhythmias and mortality (5). Although the Tp-e interval is affected by the heart rate and body surface area, the Tp-e/QTc ratio is represented as a more accurate index of VR (6). Recent studies have confirmed that these simple ECG parameters, including the Tp-e interval, Tp-e/QTc ratio, and fQRS, are very useful tools for predicting adverse cardiac events (4, 5). Therefore, I believe that these parameters will be used to a larger extent in clinical practice in the future.

In conclusion, if these findings are confirmed via further and larger prospective trials, these easily available ECG parameters such as the Tp-e interval, Tp-e/QTc ratio, and fQRS could be included in the HCM Risk-SCD Formula to more precisely assess the risk stratification in patients with HCM who are eligible for primary prophylactic ICD.