Enhanced external counterpulsation (EECP) is a mechanical form of treatment for angina. While several clinical studies appear to show that this treatment can be helpful in reducing symptoms of angina in patients with coronary artery disease (CAD), EECP has yet to be accepted by most cardiologists, and has not entered the mainstream of cardiology practice.
What is EECP?
EECP is a mechanical procedure in which long inflatable cuffs (like blood pressure cuffs) are wrapped around both of the patient’s legs. While the patient lies on a bed, the leg cuffs are inflated and deflated synchronously with each heartbeat. The inflation and deflation are controlled by a computer, which uses the patient’s ECG to trigger inflation early in diastole (when the heart relaxes and is filled with blood), and deflation just as systole (heart contraction) begins. The inflation of the cuffs occurs sequentially, from the lower part of the legs to the upper, so that the blood in the legs is “milked” upwards, toward the heart.
EECP has at least two potentially beneficial actions on the heart. First, the milking action of the leg cuffs increases the blood flow to the coronary arteries during diastole. (The coronary arteries, unlike other arteries in the body, receive their blood flow in between heartbeats, instead of during each heartbeat.) Second, by its deflating action just as the heart begins to beat, EECP creates something like a sudden vacuum in the arteries, which reduces the work the heart muscle has to perform in pumping blood. It is also speculated that EECP may help reduce endothelial dysfunction.
EECP is administered as a series of outpatient treatments. Patients receive 5 one-hour sessions per week, for 7 weeks (for a total of 35 sessions). The 35 one-hour sessions are aimed at provoking long lasting beneficial changes in the circulatory system.
How Effective Is EECP?
Several studies suggest that EECP can be quite effective in treating chronic stable angina. A small randomized trial showed that EECP significantly improved both the symptoms of angina (a subjective measurement) and exercise tolerance (a more objective measurement) in patients with CAD. EECP also significantly improved “quality of life” measures, as compared to placebo therapy. Other studies have shown that the improvement in symptoms following a course of EECP seems to persist for up to five years (though 1 in 5 patients may require another course of EECP to maintain their improvement).
How Does EECP Work?
The mechanism for the apparent sustained benefits seen with EECP is unknown. There is some evidence suggesting that EECP can help induce the formation of collateral vessels in the coronary artery tree, by stimulating the release of nitric oxide and other growth factors in within the coronary arteries. There is also evidence that EECP may act as a form of “passive” exercise, leading to the same sorts of persistent beneficial changes in the autonomic nervous system that are seen with real exercise.
Can EECP Be Harmful?
EECP can be somewhat uncomfortable, but is generally not painful. In studies, the large majority of patients have tolerated the procedure quite well.
But not everyone can have EECP. People probably should not have EECP if they have aortic insufficiency, or if they have had a recent cardiac catheterization, an irregular heart rhythm such as atrial fibrillation, severe hypertension, peripheral artery disease involving the legs, or a history of deep venous thrombosis. For anyone else, however, the procedure appears to be safe.
When Is EECP Recommended?
Based on what we know today, EECP should be considered in anybody who still has angina despite maximal medical therapy, and in whom stents or bypass surgery are deemed not to be good options. Medicare has approved coverage for EECP for patients with angina who have exhausted all their other choices.
In 2014, several professional organizations (the American College of Cardiology, American Heart Association, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons) finally agreed in a focused update that EECP ought to be considered for patients with angina refractory to other treatments.
Why Isn’t EECP Used More Often?
In general, the cardiology community has largely chosen to ignore such an outlandish form of therapy, and many cardiologists fail to to even consider offering EECP as a therapeutic option. Consequently, most patients who have angina never hear about it.
Indeed, EECP is a little outlandish. It certainly does not look like cardiology. Nobody can really explain how it works. And, from a cardiologist/s viewpoint, when you compare the relative effort and relative reimbursement of EECP to something like inserting a stent (35 sessions over 7 weeks vs. a 30-minute procedure) there is no contest. To expect cardiologists to embrace EECP with any enthusiasm simply ignores human nature.
Still, when a noninvasive treatment for angina exists that is safe and well tolerated, when available evidence (as imperfect as it may be) strongly suggests the treatment is quite effective in many patients, and when the patient being treated will be able to tell pretty definitively whether or not the treatment has helped in their own individual case (by the presence or absence of a substantial reduction in angina symptoms), it does not seem unreasonable to allow patients with stable angina to opt for a trial of that noninvasive therapy, perhaps even before they are pushed into invasive therapy.
If you are being treated for stable angina and still have symptoms despite therapy, it is entirely reasonable for you to bring up the possibility of trying EECP. Your doctor should be quite willing to discuss this possibility with you, objectively and without prejudice.