Abstract 2720: Severe Left Ventricular Dilation is Associated with Lack of Long-Term Clinical Response to Cardiac Resynchronization Therapy
Introduction: While several dyssynchrony indices have been proposed as predictors of CRT response, the importance of LV size in determining response is unknown.
Hypothesis: Non-responders have greater LV dilation before CRT than responders.
Methods: Twenty-nine pts (67 ± 13 yrs, 31% female, 55% ischemic, NYHA 3.0 ± 0.3, QRS 160 ± 28 ms, LVEF 27 ± 6%) were followed prospectively. Clinical assessment and echo (Vivid 7, GE Vingmed) were performed before and 6 months after CRT. Clinical response was defined as an improvement in NYHA class ≥ 1 and no HF hospitalizations. Echo analysis was performed blinded off-line. LV and LA volumes were measured by the biplane method of discs. The difference in pulmonic and aortic pre-ejection intervals (IVD), the delay between the basal septal and lateral segments (SLD), and the standard deviation among 12 LV segments (Ts-SD) in time to peak systolic longitudinal velocity were measured.
Results: Twenty-one pts (72%) were clinical responders, with improvements in NYHA class (3 to 1.6 ± 0.5); LVEF (29 ± 5 to 42 ± 12%); LVEDV (140 ± 44 to 123 ± 47); LVESV (99 ± 34 to 75 ± 40 ml); and IVD (33 ± 22 to 20 ± 16ms; all p < 0.01), but not SLD or Ts-SD. Non-responders had no change in these parameters; 3 were hospitalized for HF. There was no difference between the 2 groups in age, % female, % ischemic, NYHA class or QRS duration. Echo differences are shown in the Table⇓. Baseline Ts-SD correlated with baseline LVEDV (r = 0.46, p = 0.04) and LVESV (r = 0.52, p = 0.02) among responders but not non-responders. Compared to responders, non-responders had similar dyssynchrony but greater LV dilation. An LVEDV ≤ 186 or LVESV ≤ 138 ml identified responders with 91% sensitivity and 75% specificity; only 2 non-responders had LVEDV < 200 ml.
Conclusions: Patients with severe LV dilation, who otherwise meet criteria for CRT, are unlikely to have a long-term clinical response to CRT. Severe LV dilation may indicate limited myocardial viability to generate a response to CRT.