Spinal Cord Stim for Long-term Treatment of Severe Angina

Future Perspective

The efficacy of SCS in the management of severe angina, has been shown in several recent reviews.^[35,36,47] For SCS to be regarded as a routine treatment modality for severe angina pectoris, several future challenges remain:

More randomized studies on the long-term efficacy of SCS, are needed.
Further studies on proper patient selection procedures are also needed.^[46] The ideal patient for SCS is not defined at present. To select patients, suitable for SCS (i.e., those who would benefit the most and therefore potentially make SCS more cost effective), is essential. A future goal would be to define the 'gold standard' of tests, for instance to rule out and confirm ischemia, as part of this selection process. Improved patient selection will affect the patient exclusion and inclusion criteria, where confirmed relationship between ischemia and symptoms would be required (to rule out other causes of angina-like pain), while more patients without prognostic benefit from surgical interventions may in the future be suitable for SCS treatment.
Approximately 80% of the patients respond to SCS treatment after undergoing screening according to local protocols.^[17,49] These protocols might involve psychological screening, screening with TENS or temporary electrodes. However, the diagnostic value of these screening modalities have not yet been systematically studied and hence, there are no guidelines available regarding how to identify responders to SCS treatment prior to implantation. To date, no objective variables arer available for assessment in order to determine responders to SCS treatment in angina pectoris. Thus, further studies regarding proper screening procedure are warranted.
Health-related quality of life measures, using validated instruments, could improve future cost–effectiveness analyses, which are needed for SCS to be accepted as part of the routine management of severe and refractory angina pectoris.
Clinical trials aim to identify interventions to benefit future patients. Interventions should either prevent premature death or improve health-related quality of life. Patient reported outcomes allow measurement of the effect of interventions from the patient's perspective and might be a useful tool, particularly when interventions aim to improve symptoms and functional status.^[53] Since the main effects of SCS treatment in severe and refractory angina are symptom relief, improved functional status and increased quality of life it is of great importance to also include patient reported outcome assessments regarding the effect of treatment. Currently there are few data available in patients with severe or refractory angina pectoris.
Another aspect of SCS treatment in angina patients that needs to be elucidated is the effect on physical function. According to clinical experience, patients who receive SCS treatment increase their physical activity. This clinical observation is in line with results from studies reporting improved functional status on exercise ECG and improved physical function according to quality of life questionnaires.^[17,20] In previous studies, the positive long-term symptomatic effects of SCS have been interpreted as secondary to increased physical activity.^[54] However, to date there are no availabe large systematic studies regarding the effect on physical function of SCS treatment in angina pectoris.
During recent years, results from animal studies have indicated that SCS has a protective effect in induced myocardial infarction as well as in heart failure in terms of decreased myocardial ischemia, decreased myocardial infarction size, less ventricular arrhythmias and improved LVEF.^{[29,33,55,56]} It would be of great interest to apply these results in human studies and add new indications for SCS treatment.

Cite this: Spinal Cord Stimulation for Long-term Treatment of Severe Angina Pectoris - Medscape - Nov 01, 2011.

Table 1. Refractory angina pectoris patient characteristics.
	TenVaarwerk et al., (1999)¹⁵ (n = 510)	Di Pede et al., (2003)¹⁶ (n = 104)	Andréll et al., (2011)¹² (n = 139)	Andréll et al, (2010)¹⁷ (n = 235)
Mean age (years)	64	69	70	69
Men/women	367/150 72/28%	70/34 67/33%	101/38 73/27%	181/54 77/23%
Current smokers (%)	21	33	9	NA
*Concomitant diseases*
Previous myocardial infarction (%)	66	64	64	71
Previous CABG (%)	58	46	54	75
Previous PCI (%)	17	37	27	50
Hyperlipidemia (%)	28	52^†	54	66
Hypertension (%)	39	52	50	59
Diabetes mellitus (%)	NA	27	32	37
LVEF <40% (%)	24	NA	NA	16
*Pharmacological treatment*
β-blockers (%)	66	60	90	92
Calcium antagonists (%)	73	75	25	47
Long-acting nitrates (%)	79	NA	74	86
Lipid-lowering drug (%)	NA	NA	72	82
Aspirin/other platelet inhibitor (%)	NA	91	92	86
ACE inhibitors/ARB (%)	25^‡	42^‡	43	59

Executive Summary

Severe Angina Pectoris: A Moving Target (Epidemiology)

The future group of patients with refractory angina pectoris will be different from today's patients and represent a 'moving target' as risk factors, efficacy of treatment and indications continue to change.
Even if a greater number of patients who previously were considered to suffer from end-stage coronary artery disease might be eligible for revascularization procedures, and no longer 'refractory', a large number of patients suffering from refractory angina pectoris still remain.

Patient Characteristics (Demographics)

Previous reports have indicated that patients with refractory angina pectoris have a cardiac annual mortality of approximately 5%.

Treatment Options

Based on available data, spinal cord stimulation (SCS) is today considered as first-line treatment for refractory angina by the Joint Study Group of the European Society of Cardiology.
In the future, if further studies on long-term efficacy, patient selection and cost–effectiveness are positive, SCS has the potential to be moved up the treatment ladder for severe angina.

SCS in Severe Angina Pectoris (Mechanism of Action)

Spinal cord stimulation has an anti-ischemic effect, which has been demonstrated in a number of short-term studies from different centers. The anti-ischemic effect seems to be due to decreased myocardial oxygen consumption rather than due to an effect on myocardial blood flow.

Efficacy of SCS in Refractory Angina

There is strong evidence for SCS giving rise to symptomatic benefits (decrease in anginal attacks) and improved quality of life, in patients with severe angina pectoris. There is also strong evidence for SCS improving the functional status of patients with refractory angina, as illustrated by improved exercise time on treadmill or longer walking distance without angina.

Cost–effectiveness of SCS in Severe Angina

According to a limited number of studies, SCS seems to be a cost effective treatment modality with a 'break-even' after approximately 15–16 months. The foremost reason to the cost–effectiveness of SCS seems to be due to decreased hospital admissions.

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Spinal Cord Stimulation for Long-term Treatment of Severe Angina Pectoris

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