Factors Influencing Non-cardiac Side Effects of Dipyridamole When Used for Myocardial Perfusion Stress Testing

This study evaluates whether patient demographic information can be used to predict the non-cardiac side effects experienced during myocardial perfusion imaging (MPI) procedures using dipyridamole.

Heart disease is a major cause of death in the industrialized world. MPI of coronary blood flow using radiopharmaceuticals is frequently used to assess coronary artery disease. Pharmacological methods can be used to increase coronary blood flow with vasodilators such as dipyridamole or adenosine, or inotropic and chronotropic agents such as dobutamine or arbutamine. The side effects of these agents are recognized, but little is known about the factors that influence their frequency and severity.

One hundred and nineteen patients scheduled for myocardial perfusion pharmacological stress testing using dipyridamole participated in the study. Patient demographic data, which included age, sex, body mass index (BMI), diabetic status, smoker status, and daily aspirin usage, were collected before the start of the procedure. Patients underwent a 1-day rest and stress MPI procedure. The radiopharmaceuticals used were ^99mTc-Myoview or ²⁰¹Tl. The pharmacological stress procedure used dipyridamole injections based on body weight. Aminophylline was injected at the end of the stress session. Gated single photon emission computed tomography was performed for both rest and stress images. Once the patients completed the procedure, they were given a questionnaire that asked them to report the severity of any side effects experienced from the dipyridamole. Specific data types determined the statistical test best suited for analysis. The Chi-square test was used to evaluate the nominal scale data (sex, diabetic status, aspirin usage, and smoker status), Mann-Whitney test was used to compare nominal scale data and ordinal scale data (side effect severity), Student's t-test r was used for ratio scale data (age, BMI, and percent of population), and multiple linear regression and multiple logistic regression tests were used to evaluate multiple variables.

A total of 119 patients were surveyed (58 male, 61 female). The average age was 67.7 years (10.7 year standard deviation). There were no statistically significant differences in the male and female demographics except for daily aspirin usage (more common with males). Headaches were the most common side effect (50% of all patients), followed by dizziness (26%), flushing (24%), chest pain (19%), and nausea (18%). Correlations were found between patients experiencing no side effects with age (r = -0.607) and sex (P = .034); headaches with age (r = -0.706) and BMI (r = 0.464); chest pain with diabetic status (P = .017); dizziness with diabetic status (P = .039); and nausea with age (r = -0.612).

Side effects of dipyridamole are generally known, but the factors influencing incidence and severity are not. This study has shown that patient demographic information normally gathered before MPI procedures can help determine the frequency and severity of some side effects. Providing more accurate information to a patient on the possible side effects could help reduce patient anxiety and improve patient cooperation.