Spatial QT dispersion predicts non-sustained ventricula tachycardia and correlates with a confined systo-diastolic dysfunction un hypertrophic cardiomyopathy

Objectives-An increased dispersion of myocardial repolarization represents one of the mechanisms underlying the arrhythmic risk in hypertrophic cardiomyopathy (HCM). We investigated spatial myocardial repolarization dispersion indices in HCM patients with non-sustained ventricular tachycardia (NSVT) and, contextually, their main clinical determinants. Methods-Fifty-two well-matched HCM outpatients were categorized into two groups according to the presence or the absence of NSVT at 24-hours Holter electrocardiogram (ECG) monitoring. Each patient underwent a clinical examination, including Doppler echocardiogram integrated with tissue Doppler imaging, cardiac magnetic resonance, and 12-lead surface ECG to calculate the dispersion for the following intervals: QRS, Q-Tend (QTe), Q-Tpeak (QTp), Tpeak-Tend (TpTe), J-Tpeak (JTp), and J-Tend (JTe). Results-NSVT group showed only QTe dispersion and TpTe dispersion values significantly higher than the counterpart. The NSVT occurrence was independently predicted by late gadolinium enhancement presence (p=0.021) and QTe Bazett dispersion (p=0.030), the latter strongly associated with the myocardial performance index (MPI) obtained at the basal segment of the interventricular septum (p=0.0004). Conclusion-Our data support the QTe dispersion as an easy and noninvasive tool in identifying HCM patients with NSVT propensity. The strong relationship between QTe dispersion and MPI allows to hypothesize an intriguing link between electrical instability and confined myocardial areas of systo-diastolic dysfunction.