Left Ventricular Global Longitudinal Strain Does Not Improve Identification of Nonsustained Ventricular Tachycardia in Patients with Hypertrophic Cardiomyopathy

Background and Objectives: Left ventricular global longitudinal strain (LV GLS) has prognostic relevance in hypertrophic cardiomyopathy (HCM), but its incremental value for identifying nonsustained ventricular tachycardia (NSVT) documented on ambulatory monitoring is uncertain. We examined whether signed LV GLS was independently associated with documented NSVT and whether it improved a fixed clinical and conventional echocardiographic model. Materials and Methods: This retrospective, single-centre cross-sectional study included 201 patients with HCM. Transthoracic echocardiography was performed on the day that 24-h ambulatory electrocardiographic monitoring was initiated. A reference logistic regression model included age, sex, maximal septal thickness, maximal left ventricular outflow tract (LVOT) gradient, and ejection fraction; signed LV GLS was then added. Discrimination and calibration were internally validated using 2000 bootstrap samples with coefficient refitting. Six secondary mechanical measures were analysed with false discovery rate control. Results: NSVT was documented in 115 patients (57.2%). Median LV GLS was −11.3% [interquartile range, −14.3 to −9.0] with NSVT and −10.9% [−14.3 to −9.2] without NSVT (p = 0.819); the 0.4-percentage-point difference lies within the measurement variability of LV GLS, and the two distributions overlapped almost completely. The adjusted odds ratio (OR) for LV GLS per 1-percentage-point increase was 0.962 (95% confidence interval [CI], 0.884–1.047; p = 0.372). The apparent area under the curve was 0.645 (95% CI, 0.564–0.724) for the reference model and 0.644 (95% CI, 0.564–0.723) after adding LV GLS (paired difference, −0.001; 95% CI, −0.029 to 0.027; likelihood-ratio p = 0.370); optimism-corrected values were 0.606 and 0.598. In exploratory analyses, higher global radial strain was associated with lower odds of NSVT (OR per standard deviation, 0.619; 95% CI, 0.449–0.852; q = 0.020). Conclusions: LV GLS was not independently associated with documented NSVT and did not improve its discrimination beyond conventional clinical and echocardiographic variables. The exploratory radial strain association requires independent confirmation.