Correspondence from the world of cardiology
Is it time for a re-assessment of EECP in the UK?
External enhanced counter pulsation (EECP) is a validated, safe, non-invasive treatment for angina and heart failure. To date, more than 300,000 people worldwide have been treated, with 15,000 involved in clinical trials. The 2013 European Society of Cardiology (ESC) Guidelines on the Management of Stable Coronary Artery Disease1 give EECP a level 2a recommendation, meaning that the treatment should be considered for patients with refractory angina. The recommendation was made following a review of published data on the mechanisms of action and clinical benefits of EECP. The ESC concluded that the results of these studies prove the concept and clinical effectiveness of EECP.
EECP and its invasive counterpart, the intra-aortic balloon pump (IABP), began parallel development in the late 1950s and both are now clinically established in North America, China, Russia, India and the Middle East. By contrast, EECP remains largely unknown in the UK, with only three active treatment centres. In 10 years, less than 800 UK patients have received treatment. The majority of UK cardiologists have little or no clinical experience with EECP and in primary care it remains almost completely unknown.
The effects of EECP treatment on the left heart and coronary circulation are identical to those of the IABP. Both reduce afterload and myocardial oxygen demand. EECP also augments arterial blood flow to other organs such as the brain, kidneys and skin and, by enhancing venous return to the right heart, increases both preload and cardiac output.
Possible mechanisms of action include improved diastolic left ventricular (LV) filling, improved endothelial function, coronary collateral recruitment, neurohormonal and cytokine changes, neovascular growth, improved microvascular function and peripheral muscle training. There is ongoing research in all these areas. The increased volume and velocity of coronary blood flow increases endothelial shear stress, leading to a rise in nitric oxide levels and falls in endothelin-1, B-type natriuretic peptide and asymmetric dimethyl arginine. These changes are sustained for many weeks after a course of treatment. There are also falls in levels of cytokines, such as TNF–α and MCP-1. Improvements in endothelial function, arterial stiffness and flow mediated vasodilatation occur in active EECP, but not sham EECP-treated individuals. After one hour of active EECP there is a significant rise in platelet cyclic guanosine monophosphate (GMP) levels, equating to increased nitric oxide synthase activity. Exercise and stress lead to a rapid rise in peripheral blood endothelial progenitor cell numbers, but this rise is blunted in the elderly and in the presence of endothelial dysfunction. EECP causes a rise in peripheral blood populations of bone marrow derived endothelial progenitor cells and a rise in monocyte/macrophage derived endothelial-like cells. These cells secrete vascular endothelial growth factors (VEGF) stimulating angiogenesis. Some of the benefits of treatment are through peripheral muscle training, suggesting an important role for EECP in cardiac rehabilitation. Treatment also affords prolonged one-to-one contact time with trained therapists, which may provide additional psychological support.
Symptoms and exercise improved
EECP improves symptoms and exercise capacity. It reduces angina class, heart failure level and nitrate consumption in 80% of cases of refractory angina, with more than 60% maintaining benefit five years after a single 35-hour course. Treatment reduces hospital readmission rates and visits to emergency departments, outpatient clinics and GP surgeries. It has been shown to be cost effective.
Other, non-cardiac conditions may benefit from EECP, including peripheral vascular disease, erectile dysfunction, renal impairment, chronic venous ulcers and even sleep apnoea and depression. It can improve functional recovery after ischaemic stroke and may enhance the effects of thrombolysis when used in acute thrombo-embolic cerebrovascular events.
In the UK in 2009, EECP was subjected to a systematic review and economic analysis,2 with the conclusion then that there was not enough firm evidence to recommend its use in standard clinical practice. Much of what we know about its mechanisms of action has been published since that review, leading to the recent ESC recommendations. It is therefore time for the use of EECP in the UK to be re-assessed.
Conflict of interest
RR runs the EECP unit at Alexander House Private Medical Clinic in Wimbledon, London, and has received honoraria from Vasomedical Inc. USA.
15 Princes Road, Wimbledon, London,
1. Montalescot G, Sechtem U, Achenbach S, et al. The task force on the management of stable coronary artery disease of the European Society of Cardiology. 2013 ESC guidelines on the management of stable coronary artery disease. Eur Heart J 2013;34:2949–3003. http://dx.doi.org/10.1093/eurheartj/eht296
2. McKenna C, McDaid C, Suekarran S, et al. Enhanced external counterpulsation for stable angina or heart failure: a systematic review and economic evaluation. Health Technol Assess 2009;13. http://dx.doi.org/10.3310/hta113240