Impact of extracorporeal shockwave myocardial revascularization on the ischemic burden of refractory angina patients: a single photon emission computed tomography study.

BACKGROUND

Extracorporeal shockwave myocardial revascularization (ESMR) is a non-invasive treatment designed to improve symptoms in refractory angina (RA) patients. Enhanced perfusion through local vasodilation and neo-capillarization is postulated to be the mechanism of the observed clinical benefit. However, the impact of ESMR on the ischemic burden of RA patients has not been adequately assessed.

METHODS

One-hundred twenty-one consecutive RA patients suitable for ESMR were treated. Twenty-nine RA patients not suitable for treatment were clinically followed-up as a control group for clinical endpoints. ESMR-treated patients underwent baseline and 6-month single photon emission computed tomography (SPECT) to evaluate the changes in ischemic burden. The operator was blinded to the pre/post-treatment status of the SPECT exam. The primary endpoint was the difference in summed stress score (SSS) and summed difference score (SDS) between follow-up and baseline SPECTs. Secondary endpoints included the changes in Canadian Cardiovascular Society (CCS) angina class and nitroglycerin use between 6-month follow-up and baseline. Clinical endpoints were further compared between ESMR-treated patients and the control group.

RESULTS

Following ESMR, a significant reduction in the ischemic burden was observed (follow-up SSS: 14.2±10 vs. baseline SSS: 21.2±9.42, P<0.0001; follow-up SDS: 4.6±5.9 vs. baseline SDS 10.2±7.9, P<0.0001) including less patients with moderate to severe ischemia (19% vs. 46% P<0.0001). CCS class and nitroglycerin use were significantly reduced (CCS: 1.5±0.6 vs. 2.7±0.6, P<0.0001; patients needing nitroglycerin: 24% vs. 64%, P<0.0001). When compared to the control group, CCS class reduction, nitroglycerin use and hospitalizations were significantly lower for ESMR treated vs. non-treated RA patients at 6-month follow-up.

CONCLUSIONS

In this single-center cohort of RA patients undergoing ESMR treatment and serial myocardial perfusion imaging, ESMR was associated with a significant reduction in the ischemic burden. These findings provide a physiological rationale and mechanism for the observed clinical benefit.