Long-term effects of spinal cord stimulation on myocardial ischemia and heart rate variability: results of a 48-hour ambulatory electrocardiographic monitoring.

BACKGROUND: Spinal cord stimulation (SCS) has analgesic properties and may be used to treat pain in patients with therapeutically refractory angina who are unsuitable for myocardial revascularization. Some studies have also demonstrated an anti-ischemic effect. The aim of this study was to evaluate the long-term persistence of the effects of SCS on myocardial ischemia and on heart rate variability. METHODS: Fifteen patients (9 males, 6 females, mean age 76 +/- 8 years, range 58-90 years) with severe refractory angina pectoris (Canadian class III-IV), on optimal pharmacological therapy, unsuitable for myocardial revascularization and treated with SCS for a mean follow-up of 39 +/- 27 months (range 9-92 months) were studied. Eleven patients had had a previous myocardial infarction and 5 a coronary artery bypass graft. The mean ejection fraction was 54 +/- 7% (range 36-65%). All patients underwent 48-hour ambulatory ECG monitoring and were randomly assigned to 24 hours without SCS (off period) and 24 hours with SCS (on period). The primary endpoints were: number of ischemic episodes, total duration of ischemic episodes (min), and total ischemic burden (mV*min). RESULTS: The heart rate was not statistically different during the off and on SCS periods (median 64 and 67 b/min respectively). The number of ischemic episodes decreased from a median of 6 (range 0-29) during the off period to 3 (range 0-24) during the on period (p < 0.05). The total duration of ischemic episodes decreased from a median of 29 min (range 0- 186 min) during the off period to 16 min (range 0-123 min) during the on period (p < 0.05). The total ischemic burden decreased from a median of 2.5 mV*min (range 0-19.5 mV*min) during the off period to 0.8 mV*min (range 0-13 mV*min) during the on period (p = NS). The heart rate variability parameters were similar during the on and off periods. CONCLUSIONS: SCS exerts long-term anti-ischemic effects.

[Epidural spinal stimulation in the treatment of refractory angina pectoris. Its clinical efficacy, complications and long-term mortality. An Italian multicenter retrospective study]. / La stimolazione spinale epidurale nel trattamento dell'angina pectoris refrattaria. Efficacia clinica, complicanze e mortalità a lungo termine. Studio retrospettivo multicentrico Italiano.

BACKGROUND: Spinal cord stimulation has been used for many years in the treatment of refractory angina pectoris. Its anti-anginal and anti-ischemic effect has been well documented in several studies, but the long-term efficacy, safety and survival rate are not well known. The aim of this study was to carry out a retrospective analysis of a series of patients from the Italian Multicenter Registry, the data of which were collected in five centers, by means of a questionnaire. METHODS: One hundred and thirty patients (83 males, 47 females, mean age 74.8 +/- 9.8 years) were submitted to spinal cord stimulator implantation for refractory angina pectoris in the period 1988-1995 and controlled during a mean follow-up of 31.4 +/- 25.9 months. A previous myocardial infarction had already occurred in 69.3% of patients, whereas in 67.6% multivessel coronary artery disease was documented. A left ventricular dysfunction (ejection fraction < 0.40) was present in 34% of patients; bypass surgery and coronary angioplasty were performed in 49.6% and in 27% of patients respectively. In 96.3% of cases revascularization procedures were not advisable. RESULTS: A complete follow-up of 116 patients (89.2%) was available. The spinal cord stimulator induced a significant reduction in NYHA functional class from 2.5 +/- 1.2 to 1.5 +/- 0.9 (p < 0.01). During the follow-up 41 patients (35.3%) died, and in 14.2% a new acute myocardial infarction developed. The total percentage of minor spinal cord stimulation-related complications was 6.8%. No major complications occurred. The annual total mortality rate was 6.5%, whereas the cardiac mortality rate was 5%. Compared to the survivors, patients who died showed a higher incidence of left ventricular dysfunction, previous myocardial infarction and bypass surgery at implantation. CONCLUSIONS: In our experience, spinal cord stimulation is an effective therapy in patients affected by refractory angina pectoris and who cannot undergo revascularization procedure. The complication rate is low, with the total and cardiac mortality showing a trend as that reported for patients with similar coronary disease.

Effects of oral calcium-antagonists in spontaneous angina. Verapamil and nifedipine in a double-blind cross-over trial.

Verapamil and nifedipine, two calcium-antagonist drugs, were evaluated in a double-blind cross-over trial. The study was performed in 15 patients admitted to our Coronary Care Unit for spontaneous angina. Before and after a 24 hours placebo period, oral verapamil 480 mg daily and oral nifedipine 60 mg daily were administered alternatively. Symptomatic as well as asymptomatic ischemic episodes with ST segment elevation or depression and ventricular and supraventricular ectopic beats were documented by continuous electrocardiographic Holter monitoring. The average number of attacks during the placebo periods was 243; the number of attacks decreased to 129 during verapamil treatment (P less than 0.05) and to 57 during nifedipine treatment (P less than 0.01). Ventricular ectopic beats decreased with both drugs while supraventricular ectopic beats decreased only during verapamil treatment. The difference was not statistically significant because of a small number of observations. In conclusion the two drugs appear to be effective in the management of patients with unstable angina at rest, especially in the variant form.