Acetylcholine induced epicardial and microvascular spasm causes myocardial ischemia in patients with chest pain and normal coronary arteries

Purpose: Coronary microvascular (MV) dysfunction plays a pathogenic role in patients with angina pectoris despite angiographically normal coronary arteries (APNCA). Functional coronary vasomotor abnormalities such as distal vessel epicardial and MV spasm, have been proposed as a plausible explanation for angina in these patients and these can be triggered in the catheter lab with the administration of intracoronary acetylcholine (Ach). However, an unequivocal relation between Ach induced spasm and objectively documented myocardial ischemia has not been categorically demonstrated. We therefore sought to assess whether Ach induced diffuse distal epicardial vasoconstriction (≥75% diameter reduction) or coronary MV spasm (reproduction of symptoms with ECG changes and no epicardial spasm)can cause transient echocardiographic changes suggestive of myocardial ischemia. Methods: From February to October 2012, 50 patients (19 men, aged 60.5±8.9) with stable APNCA and no other comorbidities were assessed with intracoronary Ach infusion, 2D transthoracic echocardiography (before and during Ach testing), continuous ECG monitoring, and ultrasensitive cardiac troponin (USCT) measurement (before and within 4 hours after Ach testing). Results: 15 patients (30%) had a negative Ach test, 13 (26%) developed MV spasm 17 (34%) diffuse distal epicardial spasm and 5 (10%) were inconclusive. Echocardiographic findings (deceleration time, EF slope and E/A coefficient) and USCT concentrations between patients with Ach induced spasm and patients with a negative response to Ach (see figures below). ![Figure][1] Differences Ach positive/negative Conclusions: For the first time, we have demonstrated echocardiographic changes and USCT increase, suggestive of myocardial ischemia, developed in APNCA patients during Ach induced epicardial and MV coronary spasm. [1]: pending:yes