Clinical utility of left atrioventricular coupling index to define the response to cardiac resynchronization therapy

The left atrioventricular coupling index (LACI) reflects the close interaction between left atrial (LA) and left ventricular (LV) dynamics. The study aimed to verify the diagnostic value of LACI in defining the cardiac resynchronization therapy (CRT) response using echocardiography.

The study included 275 heart failure (HF) patients (65.1±12.5 years, 71.6% males, 54.6% non-ischemic cardiomyopathy) who underwent CRT implantation. To define CRT response, four echo criteria were used: I. ≥5% absolute increase in LV-ejection fraction (LV-EF), II. a combination of ≥5% absolute increase or no worsening of LV-EF and ≥10% reduction in LV end-systolic volume index, III. ≥10% reduction in LACI and IV. a combination of ≥10% reduction in LACI and ≥ 5% absolute increase or no worsening of LV-EF.

Patients had a high baseline LACI of 22.8% ±11.8% and low LV-EF of 24.5% ± 6.7%. The rate of CRT response at 6 months using criteria I, II and III was comparable (45.7%, 59.8% and 54.3% respectively), while the rate increased significantly to 72.8% when using criterion IV. During follow up (average duration of 47.1 ± 30.9 months), the CRT response rate showed a significant increase using criteria I and II (65.6% and 73.3% respectively). However, using criteria III and IV showed no significant difference (44.3% and 79.4% respectively).

Using LACI in criterion IV was superior in defining the CRT response compared to other echocardiographic criteria at 6 months with no discrepancy between the 6 month and follow up results.