Efficacy of cardiac shock wave therapy in patients with stable angina: The design of randomized, triple blind, sham-procedure controlled study

OBJECTIVE: Despite revascularization and optimal medical treatment (OMT), patients with angina often have a reduced quality of life due to inadequate relief from symptoms. Recent studies have shown that the application of shock waves may reduce angina symptoms and improve quality of life, exercise capacity, and myocardial perfusion due to the stimulation of angiogenesis. However, there is limited evidence due to small, single-arm, single-center studies of low to moderate quality. The purpose of this study is to evaluate the impact of cardiac shock wave therapy (CSWT) on exercise tolerance and angina symptoms in patients with coronary artery disease and objective evidence of myocardial ischemia who cannot undergo traditional revascularization and experience angina despite OMT in comparison to sham procedure. METHODS: We designed a randomized, triple-blind, placebo-controlled, multicentre trial (NCT02339454) to assess the efficacy of CSWT in addition to OMT in patients with stable angina and myocardial ischemia documented by exercise treadmill test (ETT). All patients were treated with stable doses of standard medical treatment 4 weeks before screening. An increase in the total exercise duration on ETT by ≥90 s from the baseline at the end of the study was set as the primary endpoint. Secondary endpoints included angina class, Seattle angina questionnaire scores, symptoms, and ECG changes during stress test. Patients underwent nine sessions of CSWT or corresponding sham procedure applied to all segments of the left ventricle, within 9 weeks. Endpoint assessments were performed at 6-month follow-up. The imaging substudies assessed the potential of CSWT to reduce stress-induced myocardial ischemia detected by dobutamine stress echocardiography, cardiac single-photon emission computed tomography, and cardiac magnetic resonance imaging. RESULTS: At two centers, 72 of the 323 screened patients were randomized in two groups (ratio 1:1): active treatment and placebo control. Study patients were predominantly males (70.8%); the mean age of the patients was 68.4±8.3 years. Of these, 44 patients had angina Canadian Cardiovascular Society class III, and 66.7% of the patients had a history of myocardial infarction. CONCLUSION: Using sham applicators, blinding study participants, investigators, and endpoints assessors to the study data as well as centralized randomization ensures rigorous methodology and low risk of bias in this large randomized controlled CSWT study.