Objective: Coronary endothelial dysfunction is the early stage of coronary artery disease. We documented the incidence and type of electrocardiographic changes during acetylcholine-induced coronary endothelial dysfunction.
Methods: Endothelial function studies were performed with intracoronary injections of 10-6, 10-5, and 10-4 mmol/l acetylcholine. Twelve-lead electrocardiograms were obtained at baseline, after each acetylcholine injection, and at the end of the procedure. Exclusion criteria included use of nitroglycerin within the previous 24 h, coronary artery disease with stenosis of more than 30% of the luminal diameter, intolerance to acetylcholine injection, and patient age younger than 18 years. Of the 75 patients enrolled, six were excluded, and 69 were analyzed (69.6% female, 30.4% male; mean age, 47.8 years).
Results: Among the 69 patients, 11.6% had right bundle branch block and 4.3% had left anterior fascicular block; one had left ventricular hypertrophy by voltage criteria, and five had electrocardiographic changes during acetylcholine injection: one had inferior ST-segment elevations, three had T-wave inversions, and one had resolution of baseline T-wave inversions. Only one of these five patients had periprocedural chest pain; it was associated with a decrease in coronary artery diameter (P<0.05). QT and corrected QT intervals were prolonged after acetylcholine administration (P<0.05). An increase of 10 ms or more in the corrected QT interval was associated with a greater increase in coronary artery blood flow (P<0.05) and a smaller decrease in coronary artery diameter (P<0.05).
Conclusion: For the diagnosis of coronary endothelial dysfunction, invasive studies should be conducted even if electrocardiograms during chest pain were negative.