Does papillary muscle free strain has predictive value in risk stratification of patients with hypertrophic cardiomyopathy?

BACKGROUND: Papillary muscle free strain has not been evaluated previously in hypertrophic cardiomyopathy (HCMP) patients. Our aim was to evaluate free papillary muscle free strain in HCMP patients and to find whether it has a value for prediction of sudden cardiac death (SCD) risk score. METHODS: Transthoracic echocardiography with tissue Doppler imaging, 2-D speckle tracking imaging (STI) of 55 HCMP patients and 45 controls were performed. HCMP patients were further divided into two groups according to their SCD risk score. Patients with risk score of less than 6 points constituted low/intermediate risk group, whereas patients with risk score of greater or equal to 6 points constituted high risk group. RESULTS: Interventricular septum, posterior wall, and left ventricular mass index were significantly higher, whereas mitral E/A ratio was significantly lower in HCMP patients compared to controls. Longitudinal apical 4C, 2C, 3C, global longitudinal LV strain, anterolateral papillary muscle (ALPM), posteromedial papillary muscle (PMPM) free strain were significantly reduced in HCMP group compared to control group. Global longitudinal strain and ALPM free strain were significantly lower in patients with high SCD risk score (-14.6 (-17.4 - -13.1) vs -11.6 (-13.2 - -10.1), p = 0.001 and -17.1 (-20.3 - -14.0) vs -9.2 (-12.6 - -7.5), p<0.001, respectively. Global longitudinal strain and ALPM free strain were statistically significantly correlated with SCD risk score (r = 0.480, p<0.001 and r = 0.462, p<0.001, respectively). Global longitudinal strain value of -12.60% had a sensitivity of 73.3% and specificity of 82.5% for predicting high SCD risk score (AUC: 0.787, 95% CI: 00.643–0.930, p = 0.001). ALPM free strain value of -12.95% had 66.7% sensitivity and 77.5% specificity for predicting high SCD risk score (AUC: 0.766, 95% CI: 0.626–0.905, p = 0.003). CONCLUSION: Papillary muscle free strain was reduced in HCMP patients. It might be used in risk stratification of these patients.