Cardiac shock-wave therapy in the treatment of coronary artery disease: systematic review and meta-analysis

Abstract

Aim: To systematically review currently available cardiac shock-wave therapy (CSWT) studies in humans and perform meta-analysis regarding anti-anginal efficacy of CSWT.

Methods: The Cochrane Controlled Trials Register, Medline, Medscape, Research Gate, Science Direct, and Web of Science databases were explored. In total 39 studies evaluating the efficacy of CSWT in patients with stable angina were identified including single arm, non- and randomized trials. Information on study design, subject's characteristics, clinical data and endpoints were obtained. Assessment of publication risk of bias was performed and heterogeneity across the studies was calculated by using random effects model.

Results: Totally, 1189 patients were included in 39 reviewed studies, with 1006 patients treated with CSWT. The largest patient sample of single arm study consisted of 111 patients. All selected studies demonstrated significant improvement in subjective measures of angina symptoms and/or quality of life, in the majority of studies left ventricular function and myocardial perfusion improved. In 12 controlled studies with 483 patients included (183 controls) angina class, Seattle Angina Questionnaire (SAQ) score, nitrates consumption were significantly improved after the treatment. In 593 participants across 22 studies the exercise capacity was significantly improved after CSWT, as compared with the baseline values (in meta-analysis standardized mean difference SMD = -0.74; 95% CI, -0.97 to -0.5; p < 0.001).

Conclusions: Systematic review of CSWT studies in stable coronary artery disease (CAD) demonstrated consistent improvement of clinical variables. Meta-analysis showed a moderate improvement of exercise capacity. Overall, CSWT is a promising non-invasive option for patients with end-stage CAD, but evidence is limited to small sample single-center studies. Multi-center adequately powered randomised double blind studies are warranted.

Keywords: Cardiac shock wave therapy; coronary artery disease; refractory angina; stable angina pectoris.

Fig. 1

Study flow diagram

Fig. 2

Meta-analysis of overall impact of cardiac shock wave therapy on exercise capacity

Fig. 3

Funnel plot of the meta-analysis. The standardized mean difference (SMD) on the x-axis is plotted against the standard error (SE) of the log(SMD) on the y-axis. A symmetrical distribution of studies indicates the absence of publication bias. An asymmetrical distribution with, for example, relatively more smaller studies with a positive result (in the lower right part of the plot) would suggest the presence of publication bias

Fig. 4

Changes of left ventricular ejection fraction evaluated by echocardiography in available cardiac shock wave therapy studies. * = p<0.05 compared to baseline, ^ = no significant changes, no figures indicated

Fig. 5

Changes of left ventricular ejection fraction evaluated by magnetic resonance imaging in cardiac shock wave therapy studies. *=p<0.05 compared to baseline

Fig. 6

Changes of left ventricular end diastolic diameter in cardiac shock wave therapy studies. *=p<0.05 compared to baseline, ^ = no significant changes, no figures indicated

Fig. 7

The methodology of cardiac shock wave therapy. a Shock wave generator system (Medispec, Germantown, MD, USA) and cardiac imaging system (Vivid i, GE Healthcare, Horten, Norway). b Shock wave focal zone alignment: Position of the sub-segment on the 2-dimensional image determined by X and Y coordinates (1). The shockwave applicator position is identically adjusted along X- and Y-axes corresponding to the X and Y coordinates of the ultrasound image (2)