945-121 The Paradoxical Hypertensive Systolic Blood Pressure Response to Dipyridamole Infusion—What are its Etiology and Implications?

Abstract

To evaluate the etiology and implications of a paradoxical increase in systolic blood pressure (SBP) following dipyridamole infusion (0.56 mg/kg), we characterized the hemodynamic, symptomatic, electrocardiographic, and image findings in 341 consecutive patients undergoing clinically indicated stress myocardial perfusion studies from January to October, 1993. Most patients (n = 292) experienced a typical, generally mild, hypotensive SBP response (range 0–73 mmHg, average 22 mg Hg). Among 49 patients with a hypertensive SBP response (range 2–81 mmHg, average 27 mmHg), 18 were considered mild (0–19 mmHg), 22 were moderate (20–39 mmHg) and 9 were severe ( ≥ 40 mmHg). In those with a hypertensive compared to those with a typical SBP response, no significant difference was found in the prevalence of coronary vascular territories demonstrating total scintigraphic defects (0.88 vs 0.73) or reversible defects (0.51 vs 0.46). Heart rate increased directly in parallel with SBP (p < 0.05). Comparing hypertensive to typical responders, the presence of symptoms of headache or induced pain in the chest, abdomen, neck or jaw (20/49 vs 77/292, p < 0.05) were found more frequently. Significant ST segment depression was also more frequent in the hypertensive group (9/49 vs 19/292, p < 0.05). Finally, mild hypertensive responders demonstrated no difference in the nature or frequency of induced symptoms, electrocardiographic, or heart rate changes compared to those with the typical SBP response. These results suggest that a moderate or severe paradoxical hypertensive SBP response to dipyridamole infusion is not specific for induced ischemia but more often likely relates to induced pain symptoms, another cause of increased cathecholamine levels. This response does not appear to relate to the presence or extent of coronary artery disease or to the presence or nature of induced image abnormalities.