New Treatment For Ischaemic Heart Disease (Refractory Angina)

Even as the treatment of ischaemic heart disease has improved significantly, there remains some patients who are not well controlled with maximum possible drugs and who are not good candidates for either coronary artery bypass grafting or percutaneous transluminal angioplasties. This is especially so as the life expectancy is increasing. These patients are having refractory angina. Refractory angina is defined as a chronic condition caused by clinically established reversible myocardial ischemia in the presence of coronary artery disease, which cannot be adequately controlled by a combination of best medical therapy, angioplasty or coronary artery bypass operations. The presence of reversible myocardial ischaemia should be clinically established to be the cause of the symptoms. Chronic angina is defined as angina with duration of more than 3 months. The incidence of refractory angina is around 30 per million inhabitants per year; other estimates are 2.5–5% of all coronary angiography procedures.

Most cases of ischaemic heart disease can be treated with drugs, angioplasties or bypass grafting and the results are very good, both having stood the test of time. Angioplasty and bypass grafting causes revascularisation i.e. restoring and improving the blood supply to the heart. But some patients do not benefit from any of these. All of us know somebody who has undergone an angioplasty or bypass surgery and have not benefited by this procedure.

Then the question that arises is why revascularisation (restoring the blood supply) is not possible in some cases? The reasons include the following:

  • Unsuitable anatomy, such as diffuse coronary sclerosis (diffuse blocking of the blood vessels), often with well-preserved left ventricular function. Sometimes called end-stage angina.
  • One or several previous CABGs and/or PTCAs which exclude further benefit or possibility of further revascularisation. >
  • Lack of adequate graft material.
  • Impaired left ventricular function in patients with previous CABG and/or PTCA.
  • Extracardiac diseases which increase perioperative and postoperative morbidity/ mortality, such as general arteriosclerotic disease, renal insufficiency, carotid stenosis and pulmonary disease.
  • Age — often in combination with the above mentioned factors.

What is Neurostimulation? How does it work in angina?

Neurostimulation is low-voltage electrical stimulation to the spinal cord that inhibits the sensation of pain. The sensation of stimulation is perceived as paraesthesia (tingling). The goal of neurostimulation is to create maximal neurostimulation-induced paraesthesia to cover the patient’s pain pattern. Spinal cord stimulation (SCS) may alleviate angina by two ways:

  • Direct pain-inhibiting effect
  • Affecting underlying ischaemia, as shown by:
    • Reduced ST segment depression
    • Increased time to ST segment depression
    • Reduced total ischaemic burden during Holter monitoring
Lakshmi Neuro Clinic

The picture above shows how the spinal cord stimulator is put in place at C7 –T2 levels. The picture below shows the spinal cord stimulator and the pulse generator (battery).

Lakshmi Neuro Clinic
Lakshmi Neuro Clinic

Indications for Spinal cord stimulation in refractory angina pectoris:

  • Stable angina pectoris with activities of daily living severely limited by angina (NYHA/CCS 3–4)
  • Insufficient improvement in functional capacity or pain control despite optimal medical treatment
  • No foreseen prognostic benefit from revascularization
  • Documented CAD (or Syndrome X)
  • Patient able to understand and comply with the treatment

Patients with chronic refractory angina pectoris are usually 70 years or more and are predominantly male. They have a history of long term (more than 10 years) coronary artery disease especially three vessel disease. They do have history of previous myocardial infarction(s) and history of previous revascularisation procedure(s). They usually will have good left ventricular function and with no serious arrhythmias.

Studies have shown that Neurostimulation for angina pectoris does not:

  • Deprive or conceal the patient of a warning signal during myocardial infarction
  • Adversely affect mortality rate
  • Increase the number of ischaemic episodes or show a rebound effect
  • Demonstrate complication rates unlike other SCS applications

The ESBY study compared Electrical Stim vs. CABG in Severe Angina Pectoris

  • 104 refractory angina patients randomized to SCS (53) or CABG (51) – the ESBY Study
  • Cardiac mortality significantly lower in SCS group (1) compared to CABG group (7)
  • Neurostimulation and CABG were equivalent methods in terms of symptom relief
  • CABG was superior during exercise testing but cerebrovascular events less with SCS
  • It was concluded that SCS may be a therapeutic alternative for patients with increased risk of surgical complications

A study on long-term outcome regarding quality of life and survival in patients in ESBY study showed that

Quality of life improved significantly 6 months after spinal cord stimulation and coronary artery bypass grafting, The results were consistent after 4·8 years. The 5-year mortality was 27·9%.

There were no significant differences between the groups.

Both methods can be considered as effective treatment options for patients with severe angina. SCS should be considered in patients with increased surgical risks and estimated to have no prognostic benefits from CABG.

A prospective, controlled, long-term follow-up study on the role of spinal cord stimulator in Cardiac syndrome X

  • Cardiac syndrome X is a condition where younger patients develop angina but the angiogram is normal.
  • 19 pts with CSX with refractory angina who underwent SCS; controll 9 comparable patients with CSX who refused SCS treatment Median (range) follow-up of 36 (15-82) months.
  • At baseline no difference in clinical characteristics and angina status. All indicators like angina episode frequency, duration & short-acting nitrate use, functional status, QOL, Exercise tolerance, exercise-induced angina and ST segment changes improved significantly at follow-up in SCS group but not in controls.
  • CONCLUSIONS: Data show that SCS can be a valid form of treatment for long-term control of angina episodes in patients with refractory CSX.

Many studies have shown that spinal cord stimulator causes

  • Fewer hospital admissions: post CABG = 0.97 per patient year vs. post SCS = 0.27 per pt. year (p=0.02) and Reduced average length of stay: post CABG 8.3 days vs. post SCS 2.6 days (p=0.04) leading to significant savings (upto £ 2,051 per patient year).
  • ~50% reduced frequency of angina episodes, with reduced nitroglycerin intake.
  • 20-25% improvement in exercise capacity, with evidence of less ST-segment depression.
  • Increased functional status, as measured by a 1 to 2 class reduction in NYHA or CCS scores with improved Quality of Life.
  • Reduction in nitrate & morphine consumption.

Neurostimulation produces the following benefits when measured by exercise stress testing: Increased exercise capacity, Increased time to onset of angina, Reduced ST-segment depression.

Despite advanced and sophisticated medical and surgical procedures, a large number of patients suffer from chronic refractory angina pectoris. Spinal cord stimulation (SCS) seems to be the most promising for these patients. Controlled studies suggest SCS provides symptomatic relief equivalent to surgical or endovascular procedures, but with a lower rate of complications and re-hospitalisation. Similarly, SCS proved cost effective compared to medical as well as surgical or endovascular approaches in a comparable group of patients. This technique is still met with reluctance by the medical community. Reasons for this disinclination may be related to incomplete understanding of the mechanism of action of SCS and the fact that SCS refers to the modulation of neuroendocrine parameters rather than to revascularization, which is currently the dominant treatment paradigm in coronary artery disease.

A systematic review and meta-analysis of the use of spinal cord stimulation (SCS) in the management of refractory angina was done (BMC Cardiovascular diseases 2009; 9:13-26).

Seven RCTs were identified in a total of 270 refractory angina patients. The outcomes of SCS were found to be similar when directly compared to CABG and percutaneous myocardial laser revascularisation. The healthcare costs of SCS appeared to be lower than CABG at 2-years follow up. Conclusion: SCS appears to be an effective and safe treatment option in the management of refractory angina patients and of similar efficacy and safety to PMR, a potential alternative treatment.

So spinal cord stimulation is a suitable and comfortable alternative for patients who are not expected to have a good result as a result of angioplasties or bypass surgeries. The surgery takes about 1 hour and patient is discharged by next day; the programming of the device is done on an out patient basis.. The risks associated with a major surgery (bypass grafting) do not exist. So next time a dear one of yours undergoes a coronary angiogram and you are advised an angioplasty or bypass surgery, ask your cardiologist about the extent of the disease and the expected results. Always keep spinal cord stimulation as an alternative is specific cases (as per indications above).