Trans-pulmonary physiology in patients with severe left ventricular dysfunction using ePLAR (echocardiographic Pulmonary to Left Atrial Ratio) – relationship with heart rate response to beta-blocker therapy

Abstract

Background: Patients with severe left ventricular dysfunction (LVD) have post-capillary obstruction to pulmonary flow, corresponding to low ePLAR (tricuspid regurgitation maximum velocity / mitral E wave : DTI E’) values. The effect of this pathophysiology on heart rate response to beta-blocker therapy remains to be determined. Methods: 347 patients with severe LVD in sinus rhythm (EF<35%) were studied before/after beta-blocker therapy. ePLAR values were compared with a predetermined normal population (n=1000). Results: Initial ePLAR values (0.2±0.1m/s, 71±12 years, males 59%) did not change (0.19±0.09m/s, p=ns) on most recent echo (mean therapy 2.8 years). Heart rate responders (HR≤77bpm, n=285), had significantly lower initial ePLAR values (0.19±0.1m/s) than non-responders (HR>77bpm, n=62, ePLAR 0.22±0.1m/s, p=0.039). However, between groups there was no significant difference in ePLAR values (0.18±0.08m/s vs 0.20±0.13m/s, p=ns), or E:E’ values (17.6±10 vs 16.5±9.3, p=ns) on most recent echo. LVD patients had substantially reduced treated ePLAR values compared to population normals (p<0.05 for each decade). Conclusions: Patients with severe left ventricular dysfunction have low ePLAR values consistent with post-capillary obstruction to pulmonary flow. Patients achieving target heart rate have significantly lower initial ePLAR values.