Current issues of ACP Journal Club are published in Annals of Internal Medicine


Therapeutics

Spinal cord stimulation was as effective as and less dangerous than CABG for angina

ACP J Club. 1998 Sep-Oct;129:41. doi:10.7326/ACPJC-1998-129-2-041


Source Citation

Mannheimer C, Eliasson T, Augustinsson LE, et al. Electrical stimulation versus coronary artery bypass surgery in severe angina pectoris. The ESBY study. Circulation. 1998 Mar 31; 97:1157-63.


Abstract

Question

In patients who would benefit from coronary artery bypass grafting (CABG) but are at increased risk for complications during and after surgery, is spinal cord stimulation (SCS) effective for treatment of severe angina pectoris?

Design

Randomized controlled trial.

Setting

2 hospitals in Sweden.

Patients

104 patients (mean age 69 y, 83% men) who had symptomatic but not prognostic indications for CABG and were at increased surgical risk for complications because of cerebrovascular disease, complicated coronary anatomy, diabetes mellitus, low ejection fraction, peripheral vascular disease, previous CABG, or renal dysfunction. Exclusion criteria were inability to manage SCS and myocardial infarction in the previous 6 months. Follow-up was 85%.

Intervention

53 patients were allocated to CABG and 51 to SCS. The stimulation equipment was implanted using a local anesthetic; the electrode was placed at the level of T1 to T2 and the pulse generator in a subcutaneous pouch below the left costal arch. Strong and weak pulses were programmed, and patients used the different pulses for pain relief or prophylactic treatment of angina.

Main outcome measures

Symptoms (frequency of angina, use of short-acting nitrates, and self- reported symptom relief) and myocardial ischemia assessed by exercise testing at 6 months. Secondary outcomes were all-cause mortality and cardiovascular and cerebrovascular morbidity.

Main results

Analysis was by intention to treat. Both treatments showed a similar reduction in the frequency of angina and use of nitrates (P < 0.001 for both). The SCS group had a lower mortality rate (P = 0.02) and fewer cerebrovascular events (P = 0.03) (Table). Patients in the CABG group had an improved exercise capacity (P = 0.02), less ST-segment depression (P ≤ 0.02), and increased rate-pressure product (P ≤ 0.03) with exercise. The groups did not differ for nonfatal or total morbidity or cardiac events.

Conclusion

Both CABG and SCS reduced angina symptoms in patients with high surgical risk, but SCS had lower rates of mortality and cerebrovascular events.

Sources of funding: University of Göteborg; the Swedish National Heart-Lung Foundation; Swedish Medical Research Council.

For correspondence: Dr. C. Mannheimer, Multidisciplinary Pain Centre, Department of Internal Medicine, Östra University Hospital, 416 85 Göteborg, Sweden. FAX 46-31-825892.


Table. Spinal cord stimulation (SCS) vs coronary artery bypass grafting (CABG) for patients who needed CABG but had surgical risk factors*

Outcomes at 6 mo SCS CABG RRR (95% CI) NNT (CI)
Mortality 1.9% 13.7% 86% (19 to 98) 8 (4 to 51)
Cerebrovascular events 3.8% 15.7% 76% (9 to 94) 8 (4 to 150)

*Abbreviations defined in Glossary; RRR, NNT, and CI calculated from data in article.


Commentary

SCS has been applied successfully in the treatment of many intractable pain syndromes and has been associated with improvement in symptoms of myocardial ischemia. The unique contribution of this study is its comparison with CABG using a randomized study design.

This study has several methodologic limitations, some of which have been acknowledged by the authors. These limitations should lead to a cautious interpretation of the findings. The number of patients was small, and the duration of follow-up was short. Treatment assignment could not be blinded. It should also be noted that 3 of the 7 patients in the CABG group died before surgical intervention while they were on the surgical waiting list, and this may have been the result of longer waiting times for CABG than for SCS (average of 1.9 vs 1 mo for insertion of the SCS device). Further, the mortality and stroke rates for the patients who received CABG in this study were several times higher than those usually reported for this procedure (1, 2). Patient selection could explain the high mortality and cerebrovascular morbidity rates for patients who received CABG, but the rates are exceptionally high considering the mean patient age of 69 years and their mean ejection fraction of 58%.

The role of SCS as an alternative to CABG for severe angina is still unclear. When the risks of CABG are deemed too high and standard medical therapy options have been exhausted, SCS can reasonably be considered an option for intractable pain. More clinical studies are required to establish the place of this novel approach in treatment of angina pectoris.

Gary W. Burggraf, MD
Hotel Dieu HospitalKingston, Ontario, Canada

Gary W. Burggraf, MD
Hotel Dieu Hospital
Kingston, Ontario, Canada


References

1. Topol EJ, ed. Comprehensive Cardiovascular Medicine. Philadelphia: Lippincott; 1998: 2296.

2. Roach GW, Kanchuger M, Mangano CM, et al. Adverse cerebral outcomes after coronary bypass surgery. N Engl J Med. 1996; 335:1857-63.