Angiographic and clinical characteristics according to intracoronary acetylcholine dose in patients with myocardial bridge.

OBJECTIVES

It is well known that myocardial bridge (MB) is a risk factor of vasospastic angina. However, clinical and angiographic characteristics according to different acetylcholine (ACh) dose in patients with MB are not clarified yet.

METHODS

A total 483 consecutive patients who had angiographically proven MB underwent the intracoronary ACh provocation test. ACh was injected by incremental doses of 20, 50 and 100 μg into the left coronary artery. We evaluated the clinical and angiographic characteristics of patients with MB according to 3 different ACh doses.

RESULTS

The baseline clinical and procedural characteristics are well balanced among the three groups. The MB patients who responded to the lower ACh dose (20 μg) had higher incidence of baseline spasm, severe vasospasm and diffuse long spasms (>30 mm) than those who responded to the higher doses (50 and 100 μg). The incidence of 12-month mortality and recurrent chest pain was higher in the lower ACh dose group (20 μg).

CONCLUSION

The patients with MB significantly reacting at the low ACh dose had more pronounced baseline spasm, severe and diffuse long coronary artery spasm, higher 12-month mortality and recurrent chest pain than those reacting with the higher ACh doses, suggesting that more intensive medical therapy will be required.