Implantable Spinal Cord Stimulators for Refractory Angina Pain

During spinal cord stimulation (SCS), also called dorsal column stimulation or neurostimulation, electrical impulses stimulate nerve fibres in the spinal cord, thereby inhibiting pain signals to the brain.

SCS was first used for angina in 1987. The launch of a recent US trial may indicate a renewed interest in the use of this technology for the treatment of intractable angina pain.

How It Works

A small generator, similar to a heart pacemaker, is surgically implanted, usually in the abdomen. Percutaneous leads connect to electrodes implanted in the epidural space of the spine. The implant is intended to be permanent, but it can be removed, if necessary. The physician programs the levels of stimulation and the patient uses a hand-held controller to activate the generator and adjust the intensity, as needed. The rechargeable batteries require replacement about every nine years.

Who Might Benefit

For angina treatment, SCS is an option for individuals with severe refractory disease that cannot be managed with anti-anginal drugs or revascularization procedures such as angioplasty or coronary artery bypass surgery. An estimated 483,000 Canadians have angina.[1] Based on US estimates, 10,000 Canadians may have refractory angina.[2]

Regulatory Status

Several implantable spinal cord stimulation systems are licensed by Health Canada for the broader indication of chronic pain. These include the Itrel 3® System, Synergy™ system, and RestoreADVANCED™ (all from Medtronic Inc.); the Genesis™ Neurostimulation System (Advanced Neuromodulation Systems/St. Jude Medical); and the Precision™ SCS System (Advanced Bionics/Boston Scientific).

Evidence

In 2004, an industry-sponsored review of the evidence from 830 patients in 11 controlled and uncontrolled studies concluded that there is some evidence that SCS has positive, symptomatic, long-term effects on refractory angina pain. The review also concluded that larger, longer-term controlled studies are still needed.[3]

The UK National Institute for Health and Clinical Excellence (NICE) is currently assessing spinal cord stimulation for chronic neuropathic or ischemic pain, with publication expected in November 2008.

A clinical trial of the Genesis™ Neurostimulation System began recently in the US.[4] Medtronic suspended the STARTSTIM trial of SCS in 2006; these study results have not yet been published.

Adverse Events

Infection and lead displacement or breakage are common complications of SCS.[3] Additional surgery may be required to reposition the leads or remove the stimulator. Several studies report that for many patients, pain relief from SCS appears to reach a plateau over time.[5,6]

Cost

In Canada, SCS devices range in price from $10,000 to $26,000.

[1] Chow CM, et al. Can J Cardiol 2005;21(14):1265-71.
[2] Medical Advisory Secretariat, Ontario Ministry of Health and Long Term Care. Enhanced external counterpulsation (EECP). Toronto: Ontario Ministry of Health and Long-Term Care; 2006. Available: http://www.health.gov.on.ca/english/providers/program/ohtac/tech/reviews/pdf/rev_eecp_030106.pdf
[3] Cameron T. J Neurosurg 2004;100(3 Suppl Spine):254-67.
[4] St. Jude Medical announces spinal cord stimulation pilot study for chronic angina - 53-year-old woman from Massachusetts becomes first patient implanted in trial [news release]. Plano (TX): Advanced Neuromodulation Systems; 2007. Available: http://www.ans-medical.com/includes/repository/pressrelease/AnginaPilotFirstPtImplantFeb07.doc
[5] Kumar K, et al. Neurosurgery 2006;58(3):481-96.
[6] Chua R, et al. Heart Lung Circ 2005;14(1):3-7.
[7] Yang et al. Current and future treatment strategies of refractory angina. Mayo Clin Proc. 2004;79:1284-1292. Available: http://www.mayoclinicproceedings.com/pdf%2F7910%2F7910R.pdf