ECG changes of ST segment depression (STSD) and chest pain are known to occur in some patients who undergo Dipyridamole myocardial perfusion (DPM) studies. Since dipyridamole does not increase rate- pressure product and thereby myocardial oxygen demand significantly, the mechanism for the STSD and chest pain is postulated to be coronary steal phenomenon. Our aim was to see if there is an association between dipyridamole induced STSD and chest pain with retrograde collaterals, a form of coronary steal anatomy.
Retrospective chart review of patients who had DPM study in a two year period and cardiac catheterisation within 6 months of the same. The reported symptom of chest pain was taken from the study report.The ECG and catheterisation films were analysed for the presence or absence of STSD and retrograde collaterals respectively by two blinded readers.
286 consecutive charts were reviewed and 19 patients met criteria. There were 9 males and 10 females with a mean age of 68.2 ± 2.5 (49-82). 13 had multivessel disease, 5 had single vessel disease and one had no obstructive coronary disease. 47 % (95% confidence interval (CI): 24.4-71) had STSD and 32% (95% CI: 12.6-56.6) had chest pain. Patients who develop STSD following intravenous dipyridamole were four times as likely to have collaterals on their catheterisation films than those who do not.( Relative risk 3.9, 95% CI: 1.1-14.1). The sensitivity and specificity was 78% (95% CI: 40-97.2) and 80% (95% CI: 44.4-97.5) respectively. The presence of chest pain was not associated with the presence of collaterals.
Dipyridamole induced STSD is significantly associated with the presence of retrograde coronary collaterals. There was no association of chest pain with the presence of collaterals.
The presence of STSD on ECG during DPM is a clinically important finding when assessing the need for subsequent catheterisation.
S. Sivasankaran, None.