title: Comparison of Hemodynamic Effects and Negative Predictive Value of Normal Adenosine Gated Myocardial Perfusion Scan With or Without Caffeine Abstinence.
abstract: For vasodilator stress, myocardial perfusion imaging (MPI) with at least 12-h caffeine abstinence is recommended, as it attenuates cardiovascular hyperemic response of adenosine and dipyridamole. However, many published conflicting results have shown no significant effect upon perfusion abnormalities in MPI performed without caffeine abstinence. The aim of this study was to compare the hemodynamic changes and negative predictive value (NPV) of normal MPIs with adenosine stress performed with or without caffeine abstinence. This was a prospective study that accrued 50 patients from May 2013 till September 2013 and followed till November 2014. These patients had a normal adenosine-gated MPI (GMPI) with technetium-99m methoxy isobutyl isonitrile ((99m)Tc-MIBI) after 12-h caffeine abstinence (no-caffeine). Next day, all patients had a repeat adenosine stress within 60 min after ingestion of a cup of coffee (about 80 mg of caffeine) followed by no MPI in 30 patients due to concern about radiation dose (prior-caffeine adenosine-no MPI; group A). Twenty patients opted for a repeat MPI (prior-caffeine adenosine-MPI; group B). Adenosine-induced hemodynamic response and NPV of the normal MPI with no-caffeine and prior-caffeine protocols were compared. The mean age of the study cohort was 57 ± 9 years with a male-to-female ratio of 76:24% and mean body mass index (BMI) of 26.915 ± 4.121 kg/m(2). Prevalence of hypertension, diabetes, dyslipidemia, and positive family history were 76%, 20%, 22%, and 17%, respectively. Comparison of group A with group B revealed no significant difference in demographic parameters, hemodynamic or electrocardiography (ECG) parameters, or left ventricular (LV) function parameters during adenosine intervention with prior-caffeine and no-caffeine protocols. During the follow-up, no fatal myocardial infarction (MI) was reported but 6 nonfatal MIs were reported based upon the history of short hospitalization for chest pain but without biochemical or ECG criteria for infarction (3/30 in group A and 3/20 group B). Event-free survival (EFS) for fatal MI was 100% for both the groups while EFS for nonfatal MI was 90% for group A and 85% for group B (nonsignificant P values). Kaplan-Meier survival plot also depicted nonsignificant EFS for nonfatal MI. This study did not find any significant attenuation effect upon adenosine-induced hemodynamic response and similar NPV of a normal GMPI in patients with or without caffeine abstinence. We assume that better designed prospective studies are required to validate findings of our study and provide justification for revision of guidelines about caffeine abstinence.
authors.affiliation: Department of Radiology, The Aga Khan University Hospital, Karachi, Pakistan; Department of Nuclear Cardiology, Karachi Institute of Heart Diseases, Karachi, Pakistan.
authors.forename: Maseeh
authors.initials: M
authors.lastname: Uz Zaman
authors.affiliation: Department of Nuclear Cardiology, Karachi Institute of Heart Diseases, Karachi, Pakistan; Department of Nuclear Medicine, Dr. Ziauddin Medical University, Karachi, Pakistan.
authors.forename: Nosheen
authors.initials: N
authors.lastname: Fatima
authors.affiliation: Dow University of Health Sciences, Karachi, Pakistan.
authors.forename: Areeba
authors.initials: A
authors.lastname: Zaman
authors.affiliation: Dow University of Health Sciences, Karachi, Pakistan.
authors.forename: Unaiza
authors.initials: U
authors.lastname: Zaman
authors.affiliation: Dow University of Health Sciences, Karachi, Pakistan.
authors.forename: Rabia
authors.initials: R
authors.lastname: Tahseen
keywords: Adenosine; caffeine; gated MPI; hyperemia; negative predictive value