A Novel Noninvasive Myocardial Performance Index For Ruling Out Acute Coronary Syndrome In The Emergency Department

Definitive diagnosis in patients presenting to the emergency department (ED) with chest pain is difficult due to limitations of the electrocardiogram (ECG) as the primary assessment tool. Most patients presenting with chest discomfort have a nonischemic ECG and biomarkers of myocardial necrosis within normal limits. Because of the limitation of initial risk stratification tools, many patients who do not actually have acute coronary syndrome (ACS) are admitted to hospital. The current study describes a new, noninvasive apparatus that quantifies central aortic pressure changes (dP/dt), an established indicator of myocardial contractility. We hypothesize that a higher dP/dt occurs in non ischemic chest pain than during ischemic chest pain. This appears to be a result of reduced myocardial contractility during ischemia, whereas chest pain of non cardiac origin increases dP/dt by the stress of the pain itself. The study follows 102 patients presenting at the ED with acute chest pain. In 55 patients, the device indicated chest pain to be of non cardiac origin (dP/dt index above threshold value of ≥150). Of these 55, negative ECG and myocardial enzyme dynamics ruled out coronary origin during the first twenty-four hours after admission (sensitivity 93%, negative predictive value 98% specificity 61%, positive predictive value 28%, accuracy 66%). Initial findings indicate that adding noninvasive dP/dt measurements to the classical triage of chest pain in the ED could help prevent unnecessary hospitalization in a substantial number of patients with low probability for ACS.