Endothelial Function Predicts 1-year Adverse Clinical Outcome in Patients Hospitalized in Chest Pain Unit

Background:
Endothelial function can be regarded as a marker for cardiovascular events in patients with atherosclerosis.

Objectives:
To test the hypothesis that abnormal endothelial function is associated with adverse long-term outcome in patients presenting to the ED chest pain unit (CPU).

Methods:
Following endothelial function testing, using EndoPAT 2000 in 300 consecutive subjects with chest pain and no history of coronary artery disease (CAD) presenting to the ER CPU, patients underwent coronary computerized tomographic angiography (CCTA) or single-photon emission computed tomography (SPECT) according to availability. CPU physicians and patients were blinded to the EndoPAT results until the end of the study. Patients were followed-up after 6 and 12 months for combined major adverse cardiovascular end-points (MACE), including all-cause mortality, non-fatal myocardial infarction, hospitalization for heart failure or angina pectoris, stroke, coronary artery bypass grafting and percutaneous coronary interventions.

Results:
Mean age was 50±10 years, 83% males, mean 10-year Framingham risk score (FRS) 6.6±5.9%. Median reactive hyperemia index (RHI) as a measure of endothelial function was 2.08 and mean was 2.0±0.4. During a 1-year follow-up, the 20 (6.6%) patients who developed MACE had higher 10-year FRS (10.5±8.2% vs 6.3±5.7%; p<0.001), lower baseline RHI (1.43±0.41 vs 2.10±0.44; p<0.001) and a greater extent of coronary atherosclerosis lesions (70% vs 3.9%, p<0.001) in the CPU CCTA, compared to those without MACE. RHI ≤ the median was associated with higher 1-year MACE (13% vs 0.7%, p<0.001) compared to RHI > the median. Multivariate analysis demonstrated that RHI ≤ the median is an independent predictor of coronary atherosclerosis lesions in the CPU CCTA (OR 5.98, 95% CI 03.29-10.88; p<0.001) and 1-year MACE (OR 15.207, 95% CI 2.00-115.33; p<0.01).

Conclusions:
Our findings suggest that non-invasive endothelial function testing may have clinical utility in triaging patients in the CPU and in predicting 1-year MACE.