Dyssynchrony Measurements to Predict Functional Recovery After CRT: Too Good to Be True?

Mechanical abnormalities detected with conventional echocardiography are associated with response and midterm survival in CRT

OBJECTIVES

Our aim was to identify "correctable abnormalities" using conventional grayscale and blood-pool Doppler echocardiography and evaluate their ability to predict both response and midterm survival.

BACKGROUND

Identification of mechanical abnormalities that may be corrected with cardiac resynchronization therapy (CRT) is useful for predicting echocardiographic response at 1-year follow-up.

METHODS

A total of 200 CRT patients were included. Clinical evaluation and echocardiography were performed before and after CRT to assess the presence of the mechanical abnormalities of interest (septal flash, abnormal ventricular filling, or exaggerated interventricular dependence). Response to CRT was defined as a reduction in left ventricular (LV) end-systolic volume (ESV) ≥15%. Four subgroups of extent of response were defined: LVESV reduction >26.68% (extensive remodeling); LVESV reduction 6.8% to 26.68% (slight remodeling); LVESV reduction <6.8% (no remodeling) and clinical response; and LVESV reduction <6.8% without clinical response or the occurrence of death or heart transplantation. Midterm cardiovascular survival was evaluated (mean follow-up 38 ± 19 months).

RESULTS

The presence of a correctable abnormality was independently associated with a better rate (odds ratio: 0.03 [95% confidence interval (CI): 0.01 to 0.10], p < 0.001) and extent of response to CRT (n = 59 [96.7%] for the extensive remodeling subgroup vs. n = 53 [85.5%] for the slight remodeling subgroup vs. n = 19 [47.5%] for the no remodeling with clinical response subgroup vs. n = 17 [45.9%] for the no remodeling without clinical response subgroup, p = 0.0001), as well as with increased midterm survival (hazard ratio: 0.11 [95% CI: 0.2 to 0.6]). Other independent predictors included creatinine level and LV end-systolic diameter for response; New York Heart Association functional class IV, creatinine, LV end-systolic diameter, and transmurality index for extent of response; and New York Heart Association functional class IV for cardiovascular mortality.

CONCLUSIONS

The presence of a correctable abnormality evaluated by conventional echocardiography is associated with LV reverse remodeling and better survival at midterm follow-up. Clinical characteristics and myocardial viability also have an influence.