Echo-guided extracorporeal shock wave therapy for refractory angina improves regional myocardial blood flow as assessed by PET imaging

Abstract

Purpose: Low-intensity extracorporeal shock wave (SW) therapy (SWT) has been shown to improve symptoms and exercise tolerance in patients (pts.) with coronary artery disease (CAD) not suitable for conventional revascularization strategies. Induction of neovascularization and improvement of myocardial perfusion are mechanisms hypothetized to be involved. Methods: 43 pts. with advanced CAD (mean age 67±10 years) not suitable for catheter-based or surgical revascularization were suffering from severe stable angina pectoris (CCS class III or IV) refractory to individually optimized medical treatment underwent a series of 9 echocardiography-targeted SW applications (3 SW applications/week during weeks 1, 5, and 9). The antero-septal wall (LAD territory) was targeted in 19, the lateral wall (RCX territory) in 18, and the inferior wall (RCA territory) in 6 pts. A series of 300-500 shock waves was applied per session. Anti-anginal medication (combination of 2 or 3 drugs) was kept unchanged. Regional myocardial blood flow (MBF) was measured quantitatively by NH3-PET at baseline and 4-6 weeks after completion of SWT. Results: Complications of SWT did not occur, markers of myocardial cell damage were all negative during SWT. At follow-up, 30 pts. (64%) reported improvement of angina to a tolerable level. CCS angina class decreased from 3.1±0.6 to 2.5±0.6 (p<0.0001). Maximum ergometric workload increased from 78±53 to 90±46 watts (p=0.04). MBF in the LV region targeted by SWT improved from 119+42 mL/min/100g at baseline to 129±48 mL/min/100g at follow up (p=0.047), while there was no change in the opposite wall (136±52 vs. 137±53 ml/min/100g; p=0.9). Conclusions: SWT improves symptoms in a sizeable number of pts. with chronic refractory angina. Regional improvement of MBF in the region targeted by SWT was also documented by PET imaging. Additional studies are warranted to clarify the role of SWT in the armamentarium for this challenging patient group.