Spatial QT Dispersion Predicts Nonsustained Ventricular Tachycardia and Correlates with Confined Systodiastolic Dysfunction in Hypertrophic Cardiomyopathy

Abstract

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 nonsustained 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-hour 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-T_end (QT_e), Q-T_peak, T_peak-T_end (T_pT_e), J-T_peak, and J-T_end. Results: The NSVT group showed only QT_e dispersion and T_pT_e dispersion values to be significantly higher than their counterparts. NSVT occurrence was independently predicted by late gadolinium enhancement presence (p = 0.021) and QT_e 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 QT_e dispersion as an easy and noninvasive tool for identifying HCM patients with NSVT propensity. The strong relationship between QT_e dispersion and MPI allows us to hypothesize an intriguing link between electrical instability and confined myocardial areas of systodiastolic dysfunction.

QT spatial dispersion and sudden cardiac death in hypertrophic cardiomyopathy: Time for reappraisal

“…It is reasonable that, besides the hypertrophy magnitude per se, specific gene mutation, myocardial disarray, fibrosis, and mechanical dyssynchrony might impact on the myocardial repolarization lability and, hence, the whole QT spatial dispersion [22][23][24][25][26]. Supporting this hypothesis, we previously described a poor association between the MWT and QTcd, the latter strongly associated with an echocardiographic index of global systodiastolic ventricular performance, the myocardial performance index [13].…”

“…nearly 5-year median follow-up, our data showed a significant and independent association between QTcd and SCD risk. The spatial QT interval dispersion is known to be a helpful arrhythmic marker in several cardiovascular diseases [9,10], but its clinical role in HCM remains debated [13,[17][18][19][20][21]. We recently found a QTcd >80 ms as predictive of NSVT occurrence in a small HCM study cohort [13].…”

“…The following intervals were obtained: R-R, Q-R-S, Q-Tend (QT, from the Q wave to the T wave end), Q-Tpeak (QTp, from the Q wave to the T wave peak), Tpeak-Tend (TpTe, difference between QT and QTp), J-Tend (JT, difference between QT and QRS), J-Tpeak (JTp, difference between QTp and QRS). In accordance with previously published works [9,10,13,14], the QT interval was measured from the onset of the QRS complex to the end of the T wave and, when the latter was unclear, the QT interval was defined as the intersection of the isoelectric baseline and the maximum tangent line of the T-wave terminal limb. To minimize the possible confounder of different heart rate values, each interval was also corrected according to Bazett's classic formula.…”

Assessment of repolarization abnormalities in baseline electrocardiograms of patients with myocarditis

“…Similarly, when Amoozgar et al compared patients with Kawasaki disease and a control group, they took QT interval as an index of transmural dispersion of repolarization and found that both QT and QTc interval were prolonged in the patient group (19). Prolonged QT interval in hypertrophic cardiomyopathy was associated with nonsustained ventricular tachycardia in another study (20). Another well-investigated index of transmural dispersion of repolarization is TpTe, which was shown to be helpful for predicting the risk for lifethreatening ventricular arrhythmias (21).…”

Research Progress in Formation and Application of Tp-Te Interval

“…Hypertrophic cardiomyopathy (HCM) is a common hereditary heart disease characterized by ventricular hypertrophy and myocardial fibrosis, which is significantly associated with the high risk of fatal ventricular arrhythmia events. Previous studies have suggested that increased Tp-Te interval is a risk factor for unsustainable ventricular tachycardia in patients with hypertrophic cardiomyopathy [24]. The latest study by Akbog et al [25] in 2017 Found thatTp-Te interval and Tp-Te / QT can be independent predictors of ventricular arrhythmias in HCM patients.…”