Clinical Evidence

EECP has been evaluated in randomised, sham-controlled, observational and registry settings, with the strongest clinical experience in patients with chronic stable angina or refractory angina who remain symptomatic despite guideline-directed medical therapy.^[1,3,5]

This page summarises the major trials, registry data and physiological studies, with full references provided. The strength and applicability of each finding varies according to study design and patient population.

Summary of the Major EECP Evidence

The clinical evidence base includes:

• The MUST-EECP randomised sham-controlled trial in chronic stable angina^[1]
• The International EECP Patient Registry^[3,5]
• Observational and follow-up studies in refractory angina populations^[4,5]
• Studies examining quality of life, nitrate use and exercise capacity^[2,3,6]
• Physiological studies investigating endothelial function, vascular tone and haemodynamic effects^[7,8,9]
• Selected studies in stable heart failure populations^[10]

MUST-EECP Trial

The Multicenter Study of Enhanced External Counterpulsation (MUST-EECP) was a multicentre, randomised, sham-controlled trial involving patients with angina, documented coronary artery disease and objective exercise-induced ischaemia.^[1]

Patients received 35 hours of active or sham counterpulsation. Active EECP was associated with improvement in time to exercise-induced ST-segment depression and reduction in angina episode frequency.^[1] The study remains an important foundational trial because it evaluated EECP against a sham control in a stable angina population.

International EECP Patient Registry

The International EECP Patient Registry provides real-world observational data from patients treated with EECP for chronic angina. Registry reports have described reductions in Canadian Cardiovascular Society angina class, improved quality-of-life measures and reduced nitrate use following a completed treatment course.^[3,5]

As registry data are observational, they should be interpreted as associations observed in clinical practice rather than proof of randomised treatment effect.

Angina Symptoms and Functional Capacity

Across published studies, EECP has most consistently been associated with improvement in angina burden and functional capacity in selected patients with chronic stable or refractory angina.^[1,3,5,6]

Reported benefits have included:

• Reduction in CCS angina class^[3,5]
• Fewer angina episodes^[1]
• Improved exercise tolerance^[1,6]
• Improved patient-reported functional status^[2,3]
• Improved quality-of-life measures^[2,3,5]

These outcomes are most clinically relevant in patients who remain symptomatic despite medical therapy and in whom further revascularisation is not suitable, feasible or preferred.^[5,11,12]

Quality of Life

Quality-of-life studies have reported improvements in physical limitation, symptom burden and patient-reported functional capacity following EECP in patients with chronic angina.^[2,3,5]

These findings are clinically important because many patients referred for EECP have persistent symptoms despite technically appropriate medical and interventional management.

Nitrate Use

Registry data have reported reductions in short-acting nitrate use in some patient cohorts following EECP.^[3,5]

Medication changes remain the responsibility of the treating cardiologist or physician. EECP should not be presented as a substitute for anti-anginal therapy or broader secondary prevention.

Endothelial Function and Physiological Effects

Physiological studies suggest that EECP may have effects beyond acute diastolic augmentation. Reported mechanisms include improvements in endothelial function, vascular shear stress, peripheral arterial function and mediators of vascular tone.^[7,8,9]

These findings provide mechanistic plausibility for the clinical effects reported in angina studies, but they should be interpreted as supportive physiological data rather than standalone clinical endpoints.

Selected Heart Failure Populations

EECP has also been studied in selected patients with stable heart failure and reduced functional capacity. In the PEECH trial, EECP was associated with improvements in exercise duration, NYHA functional class and selected quality-of-life measures when added to optimal pharmacologic therapy.^[10]

Heart failure remains a selected-use population rather than the primary evidence base for EECP. Suitability should be determined by the treating/referring doctor in the context of the patient's overall cardiac status, comorbidities and management plan.

Guideline Recognition

EECP has been recognised in international guideline discussions for selected patients with refractory angina or persistent symptoms despite optimal medical therapy where further revascularisation is not appropriate. The ACC/AHA focused update for stable ischaemic heart disease states that EECP may be considered for relief of refractory angina in patients with stable ischaemic heart disease.^[11] European chronic coronary syndrome guidance similarly emphasises individualised management for patients with persistent symptoms despite standard therapy, within which adjunctive options may be considered.^[12]

Clinical Interpretation

The evidence for EECP is strongest when it is positioned as an adjunctive therapy for carefully selected, clinically stable patients with persistent angina or functional limitation despite standard care.^[1,3,5,11]

EECP is not intended to replace guideline-directed medical therapy, cardiac rehabilitation, PCI, CABG or specialist cardiology care where clinically indicated. Outcomes reported in published studies should be interpreted in the context of patient selection, baseline symptom severity, comorbidities and study design.

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References

1. Arora RR, Chou TM, Jain D, Fleishman B, Crawford L, McKiernan T, Nesto RW. The Multicenter Study of Enhanced External Counterpulsation (MUST-EECP): effect of EECP on exercise-induced myocardial ischemia and anginal episodes. J Am Coll Cardiol. 1999;33(7):1833–1840. doi:10.1016/S0735-1097(99)00140-0.
2. Arora RR, Chou TM, Jain D, Fleishman B, Crawford L, McKiernan T, Nesto RW, Ferrans CE, Keller S. Effects of enhanced external counterpulsation on health-related quality of life continue 12 months after treatment: a substudy of the Multicenter Study of Enhanced External Counterpulsation. J Investig Med. 2002;50(1):25–32.
3. Michaels AD, Linnemeier G, Soran O, Kelsey SF, Kennard ED. Two-year outcomes after enhanced external counterpulsation for stable angina pectoris: from the International EECP Patient Registry. Am J Cardiol. 2004;93(4):461–464. doi:10.1016/j.amjcard.2003.10.044.
4. Lawson WE, Hui JCK, Cohn PF. Long-term prognosis of patients with angina treated with enhanced external counterpulsation: five-year follow-up study. Clin Cardiol. 2000;23(4):254–258.
5. Loh PH, Cleland JGF, Louis AA, Kennard ED, Cook JF, Caplin JL, Barsness GW, Lawson WE, Soran OZ, Michaels AD. Enhanced external counterpulsation in the treatment of chronic refractory angina: a long-term follow-up outcome from the International Enhanced External Counterpulsation Patient Registry. Clin Cardiol. 2008;31(4):159–164. doi:10.1002/clc.20117.
6. Stys TP, Lawson WE, Hui JCK, Fleishman B, Manzo K, Strobeck JE, Tartaglia J, Ramasamy S, Suwita R, Zheng ZS, Liang H, Werner D. Effects of enhanced external counterpulsation on stress radionuclide coronary perfusion and exercise capacity in chronic stable angina pectoris. Am J Cardiol. 2002;89(7):822–824.
7. Bonetti PO, Holmes DR Jr, Lerman A, Barsness GW. Enhanced external counterpulsation for ischemic heart disease: what's behind the curtain? J Am Coll Cardiol. 2003;41(11):1918–1925.
8. Braith RW, Conti CR, Nichols WW, Choi CY, Khuddus MA, Beck DT, Casey DP. Enhanced external counterpulsation improves peripheral artery flow-mediated dilation in patients with chronic angina: a randomized sham-controlled study. Circulation. 2010;122(16):1612–1620. doi:10.1161/CIRCULATIONAHA.109.923482.
9. Casey DP, Beck DT, Nichols WW, Conti CR, Choi CY, Khuddus MA, Braith RW. Effects of enhanced external counterpulsation on arterial stiffness and myocardial oxygen demand in patients with chronic angina pectoris. Am J Cardiol. 2011;107(10):1466–1472.
10. Feldman AM, Silver MA, Francis GS, De Lame PA, Parmley WW. Enhanced external counterpulsation improves exercise tolerance in patients with chronic heart failure. J Am Coll Cardiol. 2006;48(6):1198–1205. doi:10.1016/j.jacc.2005.10.079.
11. Fihn SD, Blankenship JC, Alexander KP, Bittl JA, Byrne JG, Fletcher BJ, et al. 2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease. Circulation. 2014;130(19):1749–1767. doi:10.1161/CIR.0000000000000095.
12. Knuuti J, Wijns W, Saraste A, Capodanno D, Barbato E, Funck-Brentano C, et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. Eur Heart J. 2020;41(3):407–477. doi:10.1093/eurheartj/ehz425.