Additional value of left atrial and left ventricular strain in hypertrophic cardiomyopathy patients with low to intermediate risk of sudden cardiac death

Background/Introduction In patients with hypertrophic cardiomyopathy (HCM), sudden cardiac death (SCD) risk stratification is challenging, especially in those with low to intermediate risk according to currently recommended SCD scores. The ESC HCM Risk-SCD score uses left atrial (LA) diameter but does not consider LA dysfunction, which may precede LA dilatation; additionally, it does not include a left ventricular (LV) function measure. LA reservoir strain (LARS) and LV global longitudinal strain (LVGLS) are often impaired in HCM patients and have been associated with worse outcomes, but not specifically with SCD. Purpose To assess the incremental predictive value of LARS and LVGLS for arrhythmic outcomes in HCM patients with low to intermediate SCD risk. Methods We analyzed consecutive HCM patients from three centers and excluded patients with a history of aborted SCD or sustained VT/VF, and those with no follow-up. The ESC HCM Risk-SCD score was calculated at baseline, and those who had a score <6% were included. Patients were followed up for the composite endpoint of arrhythmic events, including SCD, aborted SCD, and appropriate implantable cardiac device (ICD) therapy. Results A total of 989 patients were included (mean age 55±15; 55% male). The median SCD risk score was 2.27 (1.39-3.15). LARS and LVGLS mean values were 24.3±10.3% and -15.5±4.6%, respectively. During a median follow-up of 61 (35-117) months, a total of 71 (7.2%) patients reached the composite endpoint, including 18 (1.8%) cases of SCD, 9 (0.9%) cases of aborted SCD, and 18 (1.8%) appropriate ICD therapies. From the ROC analysis, optimal cut-off values of LARS and LVGLS for the specific arrhythmic endpoints were derived: LARS ≤23.3% and LVGLS ≥−14.1%. In univariate analysis, the ESC HCM-risk score, LARS ≤23.3% and LVGLS ≥−14.1% were significantly associated with the outcome (Figure 1). After adjusting for relevant clinical and echocardiographic variables, LVGLS ≥−14.1% and LARS ≤23.3% remained associated with the outcome (HR 1.72, 95% CI 1.02–2.91, p=0.043 and HR 1.85, 95% CI 1.08–3.18, p=0.025, respectively) together with the ESC HCM-risk score. Accordingly, Kaplan–Meier analysis showed significantly lower event-free survival in patients with impaired LARS and LVGLS (log rank test p<0.001 for both) (Figure 2). The addition of LARS and LVGLS to the ESC HCM-risk score led to a significant increase in the ability of the model to predict the composite endpoint (Chi-square difference = 9.2, p<0.001; C-statistic = 0.78, Net Reclassification Index= 0.403). Conclusion LARS and LVGLS provide an incremental value to the ESC HCM Risk-SCD score in predicting arrhythmic events among HCM patients with low to intermediate SCD risk. Therefore, incorporating LARS and LVGLS may improve risk stratification and guide decision-making for ICD implantation in these challenging patient groups.