Effect of the cold pressor test on regional myocardial blood flow in patients with coronary artery disease.

The cold pressor test is a potent alpha-adrenergic vasoconstrictor stimulus, but its effect on regional myocardial blood flow in patients with coronary artery disease is unknown. In this study, 17 patients with chest pain syndromes who were receiving beta-adrenergic-blocking drugs underwent regional myocardial blood flow determination by the xenon-133 technique before and after the cold pressor test. Nineteen of 28 regions analyzed were distal to significant coronary artery lesions (greater than 70% reduction of luminal diameter), while the remainder were in patients with normal coronary arteries. Patients with normal and stenotic coronary arteries had a similar increase in heart rate-pressure product, but in patients with normal coronary arteries, regional myocardial blood flow increased in nine of nine regions (average increase 11.6 +/- 1.3%, p less than 0.01) while either decreasing or remaining unchanged in 14 of 19 regions distal to coronary artery lesions (average decrease 13.6 +/- 1.6%, p less than 0.05). This difference between groups was significant (p less than 0.01), demonstrating an inappropriate reduction of regional myocardial blood flow and suggesting that alpha-adrenergic vasoconstriction may contribute to myocardial ischemia.