Background: Spinal cord stimulation (SCS) is effective in the treatment of severe coronary artery disease (CAD) unresponsive to anti-anginal medication or revascularization procedures. However, there is still concern about its safety.
Objective: To investigate the reliability, morbidity, and mortality aspects of SCS in patients with refractory angina pectoris by studying the predictors of outcome, defined by efficacy, adverse events and mortality, in patients with CAD and SCS.
Methods: Fifty-seven patients (18 women) treated with SCS, aged 59.8 +/- 7.6 years (mean +/- SD) were studied retrospectively. They had suffered from manifest CAD for 9.4 +/- 4.9 years; 46 of them had experienced a myocardial infarction prior to the implantation; 28 had had a previous percutaneous transluminal coronary angioplasty; and 52 had undergone coronary artery bypass surgery. The mean left ventricular ejection fraction was 51.8 +/- 13.8%. All of the patients were being treated with two or three anti-anginal drugs.
Results: During 2042 patient-months follow-up, nine of the 57 patients died (annual mortality rate 6.5%). The percentage of adverse events requiring reprogramming or surgical reintervention was reduced from 83% for 18 patients with the Medtronic ITREL lead to 33% for 39 patients with the ITREL II system. The clinical outcome was correlated positively with a left ventricular ejection fraction > 40% (P = 0.0005), and negatively with a high cholesterol level (P = 0.0042), more prior revascularizations (P = 0.028), and a higher New York Heart Association classification (P = 0.04).
Conclusions: Improvement of the SCS system reduced the equipment-related complication rate. The predictors of outcome are related to the traditional risk factors for CAD. The mortality rate of patients with refractory angina treated with SCS is similar to that of patients with CAD and stable angina pectoris.