The effect of external counterpulsation on intrinsic myocardial function evaluated by speckle tracking echocardiography in refractory angina patients: a randomized controlled trial.

Abstract

External Counterpulsation (ECP) is one of the therapeutic options in patients with refractory angina inadequately controlled by medical, interventional, or surgical therapy. The 2D Speckle Tracking Echocardiography (2D-STE) method is considered superior in assessing clinical improvement. We would like to evaluate any improvement ofmyocardial intrinsic function using 2D-STE in patients underwent standard ECP protocol (35 sessions). We conducted a double-blind randomized controlled trial. Patients with refractory angina who could not be revascularized conventionally were randomized into two groups: (1) the ECP group (300mmHg) and (2) the Sham/control group (75mmHg). ECP standard therapy was given for 35 sessions (1h/day/session). The 2D-STE data, including longitudinal strain and post systolic index (PSI) were obtained before and after therapy. 43 subjects were analyzed, with 22 subjects in ECP group and 21 control subjects (Sham group). A homogenous baseline strain was found either globally (12.42 ± 4.55 vs 12.00 ± 4.92 [-%]; P = 0.774) or segmentally/regionally (12.63 (0.01-25.16) vs 12.43 (0.01-27.20) [-%]; P = 0.570). There was no statistically significant improvement between groups in the left ventricle longitudinal strain globally (P = 0.535) and segmentally/regionally (P = 0.434). PSI parameters showed improvement in the ECP group (P = 0.049), and segments with PSI ≥ 20% seemed to improve longitudinal strains in the ECP group after therapy (P = 0.042). In conclusion, 35 ECP therapy sessions did not improve either global or segmental/regional left ventricular mechanical function in patients with refractory angina.However, the mechanical function of myocardial segments with PSS tends to improve after ECP therapy.