Quantitative relation between hemodynamic changes during intravenous adenosine infusion and the magnitude of coronary hyperemia - Implications for myocardial perfusion imaging

OBJECTIVES The goal of this study was to determine the relationship between changes in cardiac hemodynamics during intravenous adenosine (ADO) infusion, and myocardial blood flow (MBF). BACKGROUND The relationship between changes in MBF and the peripheral hemodynamic effects during peak adenosine infusion is unknown. METHODS We studied 348 (age 57 +/- 11 years; 106 females) without evidence of obstructive coronary artery disease by positron emission tomography (PET). Patients under-went [N-13]ammonia PET imaging to measure MBF and coronary vascular resistance (CVR) at rest and during a standard 6-min ADO infusion. Changes in heart rate (HR) and mean arterial pressure (MAP) were measured at baseline and during peak hyperemia. RESULTS During ADO, HR increased (delta: 24 +/- 11 beats/min) and MAP decreased (delta: -2 +/- 10 mm Hg). Overall, delta HR correlated poorly with hyperemic MBF (R = 0.10, p = 0.06) and with CVR (R = 0.11, p = 0.04). Delta MAP also showed a weak correlation with hyperemic MBF (R 0.04, p = 0.44) and with CVR (R = 0.11, p 0.04). Patients in the lowest tertile for delta HR showed a 7% lower hyperemic MBF (1.84 +/- 0.6 ml/min/g vs. 1.98 +/- 0.6 ml/min/g, p = 0.022) and an 8% higher CVR (54 +/- 20 min Hg/ml/min/g vs. 50 +/- 17 min Hg/ml/min/g, p = 0.056) compared with those in the highest tertile. Patients in the lowest tertile for delta MAP (i.e., greatest decline) showed similar hyperemic MBF, and an 8% lower CVR compared with those in the highest tertile (p = NS for both). These small differences between tertiles remain, even after adjusting for differences in age, gender, smoking status, and lipid profile. CONCLUSIONS Changes in cardiac hemodynamics during intravenous ADO are generally poor predictors of changes in MBF and CVR during peak hyperemia, and, thus, they should not be used to assess the effectiveness of vasodilator stress in myocardial perfusion imaging. (C) 2005 by the American College of Cardiology Foundation.