A rule-based method for predicting the electrical activation of the heart with cardiac resynchronization therapy from non-invasive clinical data

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Sex-dependent QRS guidelines for cardiac resynchronization therapy using computer model predictions

Cardiac resynchronization therapy (CRT) is an important treatment for heart failure. Low female enrollment in clinical trials means that current CRT guidelines may be biased toward males. However, females have higher response rates at lower QRS duration (QRSd) thresholds. Sex differences in the left ventricle (LV) size could provide an explanation for the improved female response at lower QRSd. We aimed to test if sex differences in CRT response at lower QRSd thresholds are explained by differences in LV size and hence predict sex-specific guidelines for CRT. We investigated the effect that LV size sex difference has on QRSd between male and females in 1093 healthy individuals and 50 CRT patients using electrophysiological computer models of the heart. Simulations on the healthy mean shape models show that LV size sex difference can account for 50–100% of the sex difference in baseline QRSd in healthy individuals. In the CRT patient cohort, model simulations predicted female-specific guidelines for CRT, which were 9–13 ms lower than current guidelines. Sex differences in the LV size are able to account for a significant proportion of the sex difference in QRSd and provide a mechanistic explanation for the sex difference in CRT response. Simulations accounting for the smaller LV size in female CRT patients predict 9–13 ms lower QRSd thresholds for female CRT guidelines

Left ventricular activation-recovery interval variability predicts spontaneous ventricular tachyarrhythmia in heart failure patients

BACKGROUND: Enhanced beat-to-beat variability of repolarization (BVR) is strongly linked to arrhythmogenesis and is largely due to variation in ventricular action potential duration (APD). Previous studies in humans have relied on QT interval measurements; however, a direct relationship between beat-to-beat variability of APD and arrhythmogenesis in humans has yet to be demonstrated. OBJECTIVES: This study aimed to explore the beat-to-beat repolarization dynamics within a heart failure population at the level of ventricular APD. METHODS: 43 patients with heart failure and implanted cardiac resynchronization therapy defibrillator devices were studied. Activation-recovery intervals (ARI) as a surrogate for APD were recorded from the left ventricular epicardial lead while pacing from the right ventricular lead to maintain constant cycle length. RESULTS: During mean follow-up of 23.6±13.6 months, 11 patients sustained VT/VF and received appropriate implantable cardioverter-defibrillator therapies (Anti-Tachycardia Pacing or shock therapy). ARI variability (ARIV) was significantly greater in patients with subsequent VT/VF vs. those without VT/VF (3.55±1.3 ms vs. 2.77±1.09 ms, p=0.047). Receiver operating characteristic curve analysis (AUC 0.71, p=0.046) suggested high and low risk ARIV groups for VT/VF. The Kaplan-Meier survival analysis demonstrated that the time until first appropriate therapy for VT/VF was significantly shorter in the high-risk ARIV group (p=0.028). ARIV was a predictor for VT/VF in the multivariate Cox model (HR, 1.623; 95% CI, 1.1 to 2.393; p=0.015). CONCLUSIONS: Increased left ventricular ARIV is associated with an increased risk of VT/VF in patients with heart failure

Electrical latency predicts the optimal left ventricular endocardial pacing site: results from a multicentre international registry

Cardiolog