Aldehyde dehydrogenase 2 (ALDH2) is a key enzyme that facilitates the biological metabolism of nitroglycerin. However, no study investigated the association between ALDH2 gene polymorphism and the vasodilation of coronary arteries following intracoronary administration of nitroglycerin. In the present study, we enrolled 427 patients with suspected angina pectoris. ALDH2 genotyping was performed and all patients were given 200 µg nitroglycerin in the right coronary artery during the coronary angiography. The invasive hemodynamic parameters including systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were monitored. The reference diameter and stenosis diameter of the right coronary artery were measured with the Stenosis Analysis 1.6 software. Both wild-type and mutant-type groups exhibited significant decreases in SBP, DBP values and increases in HR value after administration of nitroglycerin (P <
0.05). The wild-type group showed significantly higher absolute difference values in SBP when compared to the mutant-type group (P <
0.05). The mutant-type group exhibited significantly lower difference values and rates of change in reference diameter compared to the wild-type group (0.3±0.3 vs. 0.5±0.2, P <
0.001 for the difference value of diameter
9.6±9.5 vs. 15.8±8.5, P <
0.001 for the rate of change (%)). Conversely, no differences were observed between the wild-type and mutant-type groups in terms of the difference value and rate of change of the stenosis diameter (P >
0.05). In conclusion, ALDH2 gene polymorphism (Glu504Lys) is associated with changes in invasive hemodynamic parameters and coronary artery diameter after intracoronary injection of nitroglycerin.