Ventricular-arterial coupling in patients with heart failure treated with cardiac resynchronization therapy: may we predict the long-term clinical response?

To evaluate the effects of cardiac resynchronization therapy (CRT) on ventricular-arterial coupling (VAC) in patients with refractory congestive heart failure (HF), left bundle brunch block, and sinus rhythm. The ratio between arterial elastance (Ea) and left ventricular end-systolic elastance (Ees), the so-called VAC, defines the efficiency of the myocardium in pumping blood. Seventy-eight patients were studied with echocardiography before CRT, and 1 year later. End-systolic elastance was calculated according to the method of Chen. Arterial elastance (ratio of the systolic pressure to the stroke volume), end-systolic volume (ESV), and quality of life (QoL) (Minnesota Living with Heart Failure Questionnaire) were assessed at the baseline and after 1 year. Patients with a reduction > 15% of ESV or a decrease > 33% in QoL score were considered responders to CRT. QRS duration and interventricular delay were significantly reduced with CRT compared with baseline (156 +/- 2 vs. 195 +/- 3 ms, P < 0.001; and 25 +/- 2 vs. 55 +/- 3 ms, P < 0.001, respectively). Arterial elastance/Ees decreased significantly on CRT (2.47 +/- 1.48 vs. 1.41 +/- 0.87, P < 0.0001). The lowering of Ea/Ees was congruent to a decrease in intraventricular delay (83.1 +/- 55.7 vs. 28.4 +/- 49.5 ms, P < 0.0001) and an increase in ejection fraction (26 +/- 6.3 vs. 36.9 +/- 8.0%, P < 0.0001). Responders to CRT were 74 and 71% of the overall patient population, considering as endpoint QoL or ESV, respectively. The analysis of VAC showed a baseline cut-off value of 2, above which 88% and 69% of patients responded to CRT, considering as endpoint QoL or ESV, respectively. The non-invasive assessment of VAC may be proposed as an immediate, easy, and optimal tool for quantifying the effect of CRT in patients with HF.