Abstract 2820: New Insights into the Diastolic Response to Cardiac Resynchronisation Therapy
Purpose: Cardiac Resynchronisation Therapy (CRT) works through multiple mechanisms. To assess the contribution of an improvement in diastolic function we studied the effects of CRT on left ventricular (LV) filling pressure estimated from the ratio of the velocity of mitral inflow (E) to the velocity of annular motion (e’).
Methods: 18 patients undergoing biV pacemaker implantation were recruited. Before, and at 3 and 6 months after implantation, they underwent functional assessments (6 minute hall walk test; 6MWT, cardiopulmonary exercise test; VO2 max, and Quality of life questionnaire; QoL) and detailed transthoracic echo. At the 3 month visit patients underwent optimisation of atrioventricular and interventricular delays guided by changes in LV stroke volume. Transmitral Doppler and pulsed wave lateral mitral annular velocities were averaged from 3 consecutive heart beats. A positive response to CRT was defined as an improvement of >20% in 2 of the 3 functional tests from baseline to 3 months.
Results: Of the 18 patients recruited, 10 were responders and 8 were non-responders. E/e’ was similar between groups at baseline; at 3 months it had fallen by a mean of 21% in responders compared with 15% in non-responders, at 6 months it had fallen by a further 25% in responders but was unchanged in non-responders (table⇓). Aorto-pulmonary (AP) delay was reduced by 62% in responders compared with 33% in non-responders (p<0.05), and this correlated strongly with reduction in E/e’ (r2 = 0.79, p<0.0001).
Conclusions: Diastolic function as indicated by LV filling pressure improves after biventricular pacing, especially in responders and after optimisation. This benefit correlates with increased exercise capacity and reduced interventricular dyssynchrony, probably reflecting reduced diastolic interaction. E/e’ is a useful parameter for monitoring the effects of CRT on diastolic function.