Think coronary artery spasm!
A relatively large proportion of patients -20% to 50% in different series- continue to experience angina after coronary revascularisation with percutaneous coronary intervention (PCI) and stent implantation. It is often suggested that the reason for recurrent angina after PCI is incomplete revascularisation or non cardiac chest pain.  Investigation of these patients represents a challenge. Coronary angiography is often repeated in the search for in-stent restenosis (ISR). However, a recent study involving >28,000 post PCI subjects showed that at 24 months of follow-up <50 % of patients required repeat PCI for residual obstructive coronary artery disease CAD. (1) The other 50% did not show evidence for re-stenosis.  Coronary artery spasm and coronary microvascular dysfunction and spasm have also been described as potential mechanisms for angina in patients with recurrent or persistent exertional angina but without ISR after PCI (2-5)

A study by Ong et al (6) has highlighted the importance of coronary spasm as a cause of recurrent angina post-PCI. They demonstrated that enhanced coronary vasoconstriction represents an alternative explanation for angina in these patients, similar to findings in the ACOVA study in stable angina patients.(7)The authors assessed 1,285 patients with angiographically unobstructed coronaries (no stenosis >50 %) who underwent intracoronary acetylcholine provocation testing (ACH-test). 104 consecutive patients (42 female (40 %), mean age 64 ± 11 years) with previous stent implantation due to obstructive CAD, ongoing or recurrent exertional angina and no ISR were assessed with Ach provocation.

In fifty-one patients (49 %) ACH-test elicited epicardial coronary artery spasm (>75 % diameter reduction with reproduction of the patient’s symptoms) and microvascular spasm (reproduction of symptoms, ischemic ECG-changes and no epicardial vasoconstriction) was seen in 18 patients (17 %). The ACH-test was uneventful in the remaining 35 patients (34 %). Epicardial spasm in patients with previous PCI was usually distal and diffuse (31/51, 61 %, p < 0.01).  Epicardial and microvascular coronary spasm are frequently found in patients with stable angina after successful PCI. Intracoronary ACh test may be useful in these patients to determine the cause of Post-PCI angina and initiate appropriate medical treatment. Ong’s findings are of clinical importance as they showed that epicardial and/or microvascular coronary spam is likely to represent a frequent cause for angina in patients with previous PCI in whom ISR is not present.

References

1. Shah BR, Cowper PA, O’Brien SM et al (2010) Patterns of cardiac stress testing after revascularization in community practice. J Am Coll Cardiol 56:1328–1334
2. el-Tamimi H, Davies GJ, Sritara P et al (1991) Inappropriate constriction of small coronary vessels as a possible cause of a positive exercise test early after successful coronary angioplasty. Circulation 84:2307–2312
3. Monnink S, Tio R, Veeger N et al (2003) Exercise-induced ischemia after successful percutaneous coronary intervention is related to distal coronary endothelial dysfunction. J Invest Med 51:221–226
4. el-Tamimi H, Davies GJ, Crea F et al (1993) Response of human coronary arteries to acetylcholine after injury by coronary angi- oplasty. J Am Coll Cardiol 21:1152–1157
5. Azar RR (2010) Diffuse coronary spasm in a patient with a recent stent. JACC Cardiovasc Interv 3:459–460
6. Ong P, Athanasiadis A, Perne A, Mahrholdt, Schäufele T, Hill S, Sechtem U. (2014). Coronary vasomotor abnormalities in patients with stable angina after successful stent implantation but without in-stent restenosis. Clin Res Cardiol. 103:11-9. doi: 10.1007/s00392-013-0615-9
7. Ong P, Athanasiadis A, Borgulya G et al (2012) High prevalence of a pathologic response to acetylcholine testing in patients with stable angina pectoris and unobstructed coronary arteries. The ACOVA study (Abnormal Coronary VAsomotion in patients with stable angina and unobstructed coronary arteries). J Am Coll Cardiol 59:655–662