Background

Enhanced external counterpulsation (EECP) is a non-invasive technique that has been shown to be effective in reducing both angina and myocardial ischemia in patients not responding to medical therapy and without revascularization alternatives. The aim of the present study was to assess the long-term outcome of EECP treatment at a Scandinavian centre, in relieving angina in patients with chronic refractory angina pectoris.

Methods

55 patients were treated with EECP. Canadian cardiovascular society (CCS) class, antianginal medication and adverse clinical events were collected prior to EECP, at the end of the treatment, and at six and 12 months after EECP treatment. Clinical signs and symptoms were recorded.

Results

EECP treatment significantly improved the CCS class in 79 ± 6% of the patients with chronic angina pectoris (p < 0.001). The reduction in CCS angina class was seen in patients with CCS class III and IV and persisted 12 months after EECP treatment. There was no significant relief in angina in patients with CCS class II prior to EECP treatment. 73 ± 7% of the patients with a reduction in CCS class after EECP treatment improved one CCS class, and 22 ± 7% of the patients improved two CCS classes. The improvement of two CCS classes could progress over a six months period and tended to be more prominent in patients with CCS class IV. In accordance with the reduction in CCS classes there was a significant decrease in the weekly nitroglycerin usage (p < 0.05).

Conclusion

The results from the present study show that EECP is a safe treatment for highly symptomatic patients with refractory angina. The beneficial effects were sustained during a 12-months follow-up period.

Refractory angina pectoris is a clinical diagnosis which is characterized by chronic angina due to coronary artery insufficiency in patients who are refractory to conventional forms of treatment [1]. Treatment of coronary artery disease consists of pharmacological interventions and invasive actions such as percutaneous coronary interventions (PCI) and coronary bypass grafting (CABG). In spite of these generally successful means of treatment the number of patients with severe symptomatic ischemic chest pain has increased [2]. It has been reported that up to 15% of patients with angina pectoris meet the criteria for refractory angina [3]. This is a significant clinical problem and the search for alternative therapies have yielded some new treatments such as Spinal Cord Stimulation (SCS) [4,5], left stellate ganglion blockade [2,6], thoracic epidural anesthesia [2,7] and Enhanced External Counter Pulsation (EECP) [8]. Currently, EECP therapy is one of the most promising treatments for relieving angina and has been shown to improve exercise tolerance in patients with symptoms of stable angina pectoris [9].

EECP is a non-invasive counterpulsation technique, which uses three sets of pneumatic cuffs wrapped around the lower extremities. The cuffs are inflated sequentially at the onset of diastole, producing aortic counter pulsation, diastolic augmentation, and increased venous return. At the onset of systole, the external pressure in the cuffs is released, producing a decrease in systolic pressure. The hemodynamic effects are similar to intra-aortic balloon pumping (IABP). In contrast to IABP, EECP provides long-lasting increase in coronary blood flow [10,11]. A treatment procedure involves 1 to 2 hours/day for a total of 35 hours of therapy. Several studies have shown patient improvement with lowering in Canadian Cardiovascular Society Classification (CCS) [12,13]. In addition to relieving myocardial ischemia, EECP is associated with improved quality of life [13,14].

The aim of the present study was to evaluate the effect of EECP treatment at a Scandinavian centre on patients with refractory angina pectoris. The study was designed to examine the immediate, six months and 12 months follow-up effects on patients with severe refractory angina in whom multiple CABG and PCI have already been done and where further medical and surgical intervention were exhausted.

Methods

Patients in the study

55 patients, (47 male, 8 female, 45–89 years of age) with chronic stable refractory angina pectoris that were consecutively treated with EECP at the Kristianstad Hospital were included in this study. Eight patient experienced adverse events during the EECP treatment which resulted in termination of their treatment. These patients were not included in the follow-up investigations. The criteria for chronic stable refractory angina were defined by Mannheimer and colleagues in 2002 as "a chronic condition characterized by the presence of angina caused by coronary insufficiency in the presence of coronary artery disease which cannot be controlled by a combination of medical therapy, angioplasty and coronary bypass surgery. The presence of reversible myocardial ischemia should be clinically established to be the cause of the symptoms. Chronic is defined as a duration of more than 3 months " [1].

All patients had angiographically proven coronary stenosis (> 70%) in at least one major coronary artery and developed > 1 mm ST-segment depression or positive scintigraphic defects during exercise. For baseline characteristics and pharmacological treatment of the angina patients included in the follow-up study (47 patients), see Table 1 and 2. An informed consent was obtained from all patients included in the study. The study was performed in accordance with the Lund University Ethics Committeé.

EECP treatment

The EECP device consists of three paired pneumatic cuffs applied to the lower extremities (Vasomedical, Westbury, New York, USA). The cuffs are inflated sequentially (applying 250–300 mmHg of external pressure) during diastole, returning blood from the legs to the central circulation, producing aortic diastolic augmentation and thus increasing both venous return and cardiac output. The cuffs are then deflated at end-diastole, reducing peripheral resistance and providing left ventricular unloading. Daily one hour treatment sessions are typically administered for a total treatment course of 35 hours.

Data collection

Data on demographics, medical history, coronary disease status and medication were collected on patients before EECP treatment. No attempt was made to maintain current medication regimens throughout the study, although patients referred for EECP were considered "optimally medically managed". CCS class, antianginal medication use, and adverse clinical events were registered. Patients were interviewed by telephone six months after their last EECP treatment session, and 12 months thereafter to record anginal status and cardiac events.

Calculation and statistics

All calculations and statistics were performed using GraphpadPrism 4.0. Statistical significance was accepted when p < 0.05, using student's t-test when comparing two groups and ANOVA with Dunnett's post hoc test when comparing more than two groups. Values are presented as means ± S.E.M.