Prognostic significance of dipyridamole-induced ST depression in patients with normal 82Rb PET myocardial perfusion imaging.
Recent studies have shown that vasodilator-induced ischemic electrocardiographic (ECG) changes have incremental prognostic value over normal SPECT myocardial perfusion imaging (MPI) and identify patients at higher risk for cardiac events. The prognostic value of vasodilator-induced ischemic ECG changes in the setting of normal PET MPI has yet to be determined. We sought to determine the prognostic importance of dipyridamole-induced ischemic ECG changes in patients with normal 82Rb PET myocardial perfusion images.


METHODS
Between 2000 and 2003, 2,029 consecutive patients undergoing dipyridamole stress 82Rb PET at the University of Ottawa Heart Institute were evaluated. Patients with normal PET MPI and interpretable ECGs were enrolled. Electrocardiograms were assessed for ST depression or elevation and patients were categorized into those with and without dipyridamole-induced ischemic ECG changes. Images were graded using the 17-segment model. Follow-up information was obtained by telephone interview, from hospital records, or from treating physicians. All cardiac events (cardiac death, nonfatal myocardial infarction [MI], percutaneous coronary intervention, coronary artery bypass grafting, or angiography) were verified with hospital records.


RESULTS
Of the 629 enrolled patients with normal PET MPI, 72 patients had dipyridamole-induced ischemic ECG changes. There was no significant difference between the 2 groups in the combined endpoint (cardiac death, nonfatal MI, and revascularization) at follow-up (mean +/- SD, 27.1 +/- 13 mo). There were no cardiac deaths in either group. One (1.4%) patient with ischemic ECG changes had a nonfatal MI (0.6% annual event rate). Two (2.8%) patients with ischemic ECG changes required revascularization compared with 11 (2.0%) in the nonischemic ECG group.


CONCLUSIONS
Normal 82Rb PET confers an excellent prognosis regardless of dipyridamole-induced ST depression.
Chow
Benjamin J W
BJ
Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada. bchow@ottawaheart.ca
Wong
James W
JW
Yoshinaga
Keiichiro
K
Ruddy
Terrence D
TD
Williams
Kathryn
K
deKemp
Robert A
RA
DaSilva
Jean
J
Beanlands
Rob S
RS
D004176:Dipyridamole; D004562:Electrocardiography / Q000187:drug effects* / Q000379:methods*; D005080:Exercise Test / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000401:mortality*; D009864:Ontario / Q000453:epidemiology; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data; D015995:Prevalence; D011379:Prognosis; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012414:Rubidium Radioisotopes; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D015996:Survival Rate
D019275:Radiopharmaceuticals; D012414:Rubidium Radioisotopes; D004176:Dipyridamole