CJEM Articles: John Lam

Introduction: It is often believed that chest pain relieved by nitroglycerin is indicative of coronary artery disease origin.

Objective: To determine if relief of chest pain with nitroglycerin can be used as a diagnostic test to help differentiate cardiac chest pain and non-cardiac chest pain.

Design: Prospective observational cohort study with a 4-week follow-up of patients enrolled.

Setting: Academic tertiary care hospital, with 60 000 visits/year.

Inclusion criteria: Adult patients presenting to the emergency department with active chest pain who received nitroglycerin and were admitted for chest pain.

Exclusion criteria: Patients with acute myocardial infarction diagnosed after obtaining an ECG, patients whose chest pain could not be quantified, those for whom no cardiac work-up was done, or those who received emergent cardiac catheterization.

Results: 270 patients were enrolled. Nitroglycerin relieved chest pain in 66% of the subjects. The diagnostic sensitivity of nitroglycerin to determine cardiac chest pain was 72% (64%–80%), and the specificity was 37% (34%–41%). The positive likelihood ratio for having coronary artery disease if nitroglycerin relieved chest pain was 1.1 (0.96–1.34). Telephone follow-up at 4 weeks was performed, with a 95% follow-up rate.

Conclusions: Relief of chest pain with nitroglycerin is not a reliable diagnostic test and does not distinguish between cardiac and non-cardiac chest pain.