Severe Angina Pectoris: A Moving Target?
Over the the last decades, the incidence of acute myocardial infarction has changed, so that countries where the risk factor burden has decreased (western Europe) the incidence of myocardial infarction has decreased. In addition, major pharmacological and surgical improvements have lowered the out-of hospital mortality for an acute cardiovascular event. However, an increasing number of individuals worldwide are overweight and suffer from Type 2 diabetes mellitus, possibly increasing the number of patients with coronary artery disease (CAD) in the future.
To avoid complications (coronary events) and improve symptoms the first-line recommended treatment for stable CAD is a combination of lifestyle changes and pharmacological treatment. Additional conventional revascularization therapeutic options, when needed, include coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI). The majority of patients with angina pectoris experience satisfactory pain relief through pharmacological treatment and lifestyle modifications. However, there is a group of patients that continue to suffer from lasting and severe and disabling angina pectoris despite optimum treatment. This condition has been named refractory angina pectoris, and is defined as severe stable angina pectoris, functional class 3–4 according to the Canadian Cardiovascular Society classification (CCS) due to CAD, which is resistant to conventional pharmacological therapy and/or revascularization procedures, as listed above.[3,4] According to current guidelines, the presence of CAD should be confirmed on a recently performed coronary angiogram and by conventional diagnostic tests in order to prove the existence of current reversible myocardial ischemia. The correlation between myocardial ischemia and symptoms should ideally be ascertained before establishing the diagnosis. Patients with refractory angina pectoris have been considered to suffer from end-stage CAD, which may not be true.
During the last decade, revascularization procedures have developed rapidly, particularly PCI, resulting in a wider indication for this treatment option. As a result, patients who previously were considered as refractory to conventional revascularization procedures might now be accessible for PCI, resulting in reduced anginal problems. Alternatively, patients will risk repeated PCI procedures without symptomatic relief. As the risks of PCI will increase with the severity of disease, any interventions planned must also consider the risks for major cardiac events related to the procedure and the risks of disease recurrence at the level of the treated lesion(s). According to a recent study by Williams et al., 6.7% of all patients undergoing coronary angiography have CAD (with stenosis >70% on coronary angiography) and are on optimal medical therapy with no revascularization options.
Thus, the number of patients suffering from refractory angina is not known,[4,6,9] but the incidence has been estimated to be 30,000–100,000 per year in Europe and 50,000–200,0000 new cases each year in the USA.[4,10,11] The results are in line with an epidemiological study from Sweden, reporting an incidence of 2.5–3 inhabitants/100,000 persons/year. Refractory angina pectoris has been suggested to affect between 600,000 and 1.8 million people in the USA.[11,13]
The net effect of increasing lifestyle-related risk factors worldwide and a lowered in-hospital mortality from CAD would be an increased number of patients with symptomatic angina pectoris in the future. Even if a greater number of patients who were previously considered to suffer from end-stage CAD might be eligible for revascularization procedures and were no longer 'refractory', a large number of patients suffering from refractory angina pectoris still remains.
In addition, while severe underlying coronary atherosclerosis is still the underlying pathophysiological disorder, future refractory angina patients may possibly be somewhat different from today's patients, representing a moving target, as risk factors, efficacy of treatment and widening indications continue to change. For example, the increasing numbers of patients with diabetes mellitus may have a slightly different expression of CAD, with more peripheral and small-vessel disease as well as a slightly different symptomatology, compared with nondiabetic patients.
Future Cardiol. 2011;7(6):825-833. © 2011 Future Medicine Ltd.
Cite this: Spinal Cord Stimulation for Long-term Treatment of Severe Angina Pectoris - Medscape - Nov 01, 2011.