Association of hemodynamic response during dipyridamole stress testing with 99mTc-MIBI SPET myocardial perfusion image findings.

The aim of this study was to assess whether there is an association between changes in the heart rate and blood pressure after dipyridamole stress and abnormal scan findings detected with gated technetium-99m methoxy isobutylisonitrile (99mTc-MIBI) myocardial perfusion imaging (MPI). A total of 200 consecutive patients with known or suspected coronary artery disease underwent MPI using a 2 days stress/rest protocol. Heart rate (HR), blood pressure and electrocardiogram were monitored during the stress study. Dipyridamole-induced increase in HR ratio (peak HR/baseline HR) of more than 1.20 and decrease in systolic blood pressure (SBP) of 10 mmHg or more were defined as a normal response. Low ejection fraction (EF) was defined as EF less than 45%. Semi-quantitative measures used include summed stress score (SSS), summed difference score (SDS), end systolic volume (ESV) and left ventricular ejection fraction (LVEF). Chi-square-and regression analysis was used to assess associations between the various hemodynamic parameters and MPI abnormalities. Our results showed that 75% of patients had abnormal scans. Statistically significant associations were observed between each of the following factors and abnormal scan findings: abnormal SBP response to dipyridamole (P=0.011), increased SSS (P=0.040) and low LVEF (P=0.012). A significant association was also observed between decreased HR response and low LVEF (P=0.012). In conclusion, this study demonstrated that an abnormal hemodynamic response during dipyridamole stress test was associated with abnormal myocardial perfusion imaging scan findings, low LVEF and SSS.