Angiotensin-converting enzyme inhibitor therapy in patients non-obstructive coronary artery disease

Purpose: Patients with non-obstructive coronary arteries despite an acute coronary syndrome (ACS) are usually dismissed from specialty care with the belief that they do not have serious cardiac disease. There are no data on the impact of treatment on prognosis of these patients. We sought to determine the effectiveness of standard medical treatment in relation to coronary artery disease (CAD) status as assessed by in-hospital angiography. Methods: The EMMACE-2 (Evaluation of Methods and Management of Acute Coronary Events) registry enrolled patients who had been hospitalized for an ACS. There were 1602 patients who had cardiac catheterization that were used for this analysis. The main outcome measures were evidence-based therapies prescribed at discharge and 6-month incidence of all cause mortality. Results: The cohort consisted of 1252 patients with obstructive CAD (>50% luminal diameter obstructed) and 350 patients with non-obstructive CAD. Compared with obstructive CAD patients, non-obstructive CAD patients had significantly (p <0.0001) greater rates of aspirin (86.6% versus 76.6%), beta-blockers (77.80% versus 63.3%), and statins (91.4% versus 79.2%), and lower rates of ACE-inhibitors (57.7% versus 66.4%) prescription at hospital discharge In non-obstructive CAD patients, angiotensin-converting enzyme (ACE) inhibitor therapy was clearly (p <0.004) associated with a lower 6-month mortality (HR 0.31, 95% CI 0.03-0.78). None of the other evidence-based therapies was significantly better than ACE-inhibitors for outcomes. In obstructive CAD patients, aspirin, beta-blockers, statins and ACE-inhibitors were all significantly (p <0.05) associated with a reduced risk of 6-month mortality. Conclusion: ACE-inhibitor therapy is the most effective first-line treatment for preventing the occurrence of mortality in patients with non-obstructive CAD. Clinical practice should reflect this evidence by implementing its use as standard therapy for patients with non-obstructive disease.