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

OBJECTIVE: 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.
BACKGROUND: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.