A few small studies presented at the recent Heart Failure Society of America (HFSA) 2006 Scientific Meeting suggested that ECP could improve exercise times and NYHA symptom status in patients with systolic HF and myocardial ischemia [1,2]. In one of them, significant functional gains seen at the end of a standard ECP treatment course were still evident a year later.

The findings, along with prior observational data from patients with ischemic LV dysfunction and evolving ideas about ECP's physiologic effects, suggest it may help a broader population than the typical recipients with severe, medically refractory angina.

In ECP—sometimes referred to as EECP (for "enhanced ECP"), a name trademarked by one maker of the equipment, Vasomedical (Westbury, NY)—the patient wears a series of pressure cuffs around each leg that inflate and relax in an ECG-synchronized sequence that acutely enhances coronary flow and myocardial perfusion in diastole and lowers systolic pressure during systole [3]. A standard course consists of 35 one-hour sessions conducted over seven weeks. Other marketers of ECP systems include Cardiomedics (Irvine, CA) and ScottCare (Cleveland, OH).

The technique has detractors as well as proponents. It's been widely observed that any sustained benefits may actually stem from intensified care related to repeated office visits or even a placebo effect. Also, recent editorials have questioned the strength of evidence supporting ECP's use in angina and HF and the methods of the supporting trials, in which randomized therapy, unavoidably, wasn't truly blinded [4,5].

When we looked just at the patients with ischemic disease, the effects were very robust. The benefits were seen both in peak VO₂ and exercise time.

For example, in the MUST-EECP trial, on which approval for the severe angina indication is based, control patients underwent "placebo" ECP, in which the cuffs operated at gentler pressures. Dr Michael F O'Rourke (University of New South Wales, Darlinghurst, Australia), coauthor of one of the editorials [4], told heartwire that the trial was "not completely convincing" because the control treatment was easily distinguishable from the higher-pressure active therapy. And the CMS review that concluded against a demonstrated effect in HF was "exemplary" in its thoroughness, he said.

But ECP has support at some major institutions. "We know EECP works pretty well in people who have myocardial ischemia," Dr C Richard Conti (University of Florida, Gainesville) told heartwire. "That's my own clinical experience." About seven out of 10 people who get the procedure at his center, he said, show at least modest improvements in walking distance or treadmill time and less reliance on nitroglycerin.

Because ECP lowers vascular resistance to systolic blood flow, Conti said, it should similarly benefit patients with ventricular dysfunction related to old infarcts but who don't necessarily have ongoing angina. For the same reason, he said, he'd speculate that ECP may also work in patients with nonischemic forms of cardiomyopathy, although there's little supporting evidence for it.

The Prospective Evaluation of EECP in Congestive Heart Failure (PEECH) trial, Conti said, "comes close" to showing that the treatment works in HF independent of the syndrome's etiology [6]. "It showed some improvement. It wasn't totally dramatic but it showed something."

In PEECH, published last month and covered then by heartwire, patients with broadly defined HF who underwent a standard ECP treatment course showed significant improvements in exercise duration (p=0.013) and NYHA class (p<0.01) over six months compared with a conventionally managed control group. The apparent functional benefits were not accompanied by gains in the more objective measure of peak oxygen uptake (VO₂). An accompanying editorial criticized the trial's methodology and statistical strength and suggested a placebo effect as one likely explanation for any functional improvements [5].

Perhaps before ECP they could walk to the mailbox to get a letter. Now they can walk around the block and feel a bit better.

Appearing but not emphasized in the PEECH publication was a post hoc analysis showing improved exercise capacity six months after ECP compared with control therapy among the two thirds of patients with ischemic heart disease (p=0.010), but not in those with nonischemic HF (p=0.724).

That could suggest ECP in HF works exclusively in patients with ischemic heart disease, observed lead author Dr Arthur M Feldman (Jefferson Medical College, Philadelphia, PA). "Certainly when we looked just at the patients with ischemic disease, the effects were very robust. The benefits were seen both in peak VO₂ and exercise time," he told heartwire.

But whether ECP benefits patients with nonischemic HF remains an open question, according to Feldman. "There really weren't enough patients with nonischemic disease in the PEECH trial to get a clear assessment of that subgroup." And, he noted, patients who were older than 65 showed a "very robust" response to ECP regardless of whether their disease was ischemic or nonischemic.

What he believes based on the evidence, Feldman said, is that ECP is "an excellent adjunctive therapy for patients with ischemic heart disease" with or without compromised LV function.

O'Rourke said any sustained clinical benefits related to ECP, even when used for severe angina, probably have more to do with repeated office visits than any physiologic effect of the technique itself. "People who are attending the 35 sessions are exposed to advice and other treatments," and if they are willing to comply with the ECP treatment course, they are likely complying with other care given, he said.

Dr Michael E McIvor (St Petersburg Heart Center, FL) agreed that it's difficult to distinguish the direct effects of ECP from those resulting from the regular physician contact during a seven-week in-office treatment program. Because their treatment tends to be more intensive, he told heartwire, patients with HF are, for example, less likely to become volume-overloaded or electrolyte-imbalanced. Still, he said, there is abundant observational evidence that ECP improves function and symptom status in patients with ischemic HF, adding it could be of particular help to those who aren't candidates for bypass surgery.

At the HFSA sessions, McIvor and lead author Susan F Neill (Citrus Cardiology Consultants, Inverness, FL) described 53 patients with severe angina and systolic HF who showed significant improvements in NYHA functional class and exercise tolerance. The number of angina episodes was cut by more than half, and levels of brain-type natriuretic protein (BNP) improved significantly.

In one of the longer reported prospective follow-ups of HF patients undergoing ECP, also presented at the HFSA sessions, 35 patients receiving the angina indication showed significant functional and cardiac structural improvements after the seven treatment weeks.

According to lead author Dr Anil K Gothwal (Sound Shore Medical Center of Westchester, New Rochelle, NY), patients tended to lose some of the ground they had gained in LV systolic function and end-diastolic dimensions. But they kept their improvements in exercise capacity and still felt symptomatically better over the long term, Gothwal told heartwire.

Among the questions surrounding ECP is how it might have a sustained, clinically meaningful effect on hemodynamics and myocardial perfusion. Proposed mechanisms have included stimulation of angiogenesis and coronary collaterals, "but those are hard to prove," Conti said. He recently coauthored a study that added to other evidence suggesting that ECP provides "passive exercise," that is, replicates the physiologic effects of exercise conditioning [3]. It appears to improve vascular function and "tones up the muscles" in the legs, thereby raising exercise capacity, according to Conti. Perhaps before ECP, he said, "they could walk to the mailbox to get a letter. Now they can walk around the block and feel a bit better."

Such an effect, Conti said, could potentially put a regular conditioning program in reach of patients who previously couldn't exercise. "Those people will do better whether they've got heart failure or angina pectoris."

O'Rourke agreed that there may be a "simulated exercise" effect from ECP that could allow previously limited patients, at least those with severe angina, to sustain exercise on their own. But that idea is "largely theoretical," he said, and for real benefit would have to be combined with intensified medical therapy and lifestyle change.