Left ventricular global longitudinal strain in predicting CRT response: one more J-shaped curve in medicine

The aim of the study was: (1) to verify the hypothesis that left ventricular global longitudinal strain (LVGLS) may be of additive prognostic value in prediction CRT response and (2) to obtain such a LVGLS value that in the best optimal way enables to characterize potential CRT responders. Forty-nine HF patients (age 66.5 ± 10 years, LVEF 24.9 ± 6.4%, LBBB 71.4%, 57.1% ischemic aetiology of HF) underwent CRT implantation. Transthoracic echocardiography was performed prior to and 15 ± 7 months after CRT implantation. Speckle-tracking echocardiography was performed to assess longitudinal left ventricular function as LVGLS. The response to CRT was defined as a ≥ 15% reduction in the left ventricular end-systolic volume (∆LVESV). Thirty-six (73.5%) patients responded to CRT. There was no linear correlation between baseline LVGLS and ∆LVESV (r = 0.09; p = 0.56). The patients were divided according to the percentile of baseline LVGLS: above 80th percentile; between 80 and 40th percentile; below 40th percentile. Two peripheral groups (above 80th and below 40th percentile) formed "peripheral LVGLS" and the middle group was called "mid-range LVGLS". The absolute LVGLS cutoff values were - 6.07% (40th percentile) and - 8.67% (80th percentile). For the group of 20 (40.8%) "mid-range LVGLS" patients mean ΔLVESV was 33.3 ± 16.9% while for "peripheral LVGLS" ΔLVESV was 16.2 ± 18.8% (p < 0.001). Among non-ischemic HF etiology, all "mid-range LVGLS" patients (100%) responded positively to CRT (in "peripheral LVGLS"-55% responders; p = 0.015). Baseline LVGLS may have a potential prognostic value in prediction CRT response with relationship of inverted J-shaped pattern. "Mid-range LVGLS" values should help to select CRT responders, especially in non-ischemic HF etiology patients.