Enhanced transcardiac l-norepinephrine response during cold pressor test in obstructive coronary artery disease.

An increase in cardiac sympathetic activity can enhance coronary vasomotor tone and lower the ventricular fibrillation threshold. We compared the transcardiac l-norepinephrine responses during cold pressor test of 20 patients with normal coronary arteries with those of 23 patients with obstructive coronary artery disease. Baseline hemodynamic data did not differ in the 2 patient groups except for left ventricular end-diastolic pressures; mean values (+/- standard deviation [SD] were 10 +/- 3.7 and 15 +/- 4.5 mm Hg in patients with normal and abnormal coronary arteries (p less than 0.01). Baseline l-norepinephrine contents averaged 295 +/- 152 (normal coronary arteries) and 250 +/- 134 pg/ml (coronary artery disease) in the arterial blood, and 273 +/- 152 and 250 +/- 115 pg/ml, respectively, in the coronary sinus blood. Hemodynamic responses during cold stimulus were similar in both groups. Also, cold pressor-induced increases in arterial and coronary sinus l-norepinephrine contents were balanced in patients with normal coronary arteries, averaging 19 +/- 30 and 17 +/- 37%, respectively. In patients with coronary artery disease, however, a 26 +/- 58% increase in arterial l-norepinephrine contents was associated with a 58 +/- 62% increase in coronary sinus l-norepinephrine contents (p less than 0.02), suggesting myocardial l-norepinephrine net release. It is concluded that transcardiac l-norepinephrine responses during cold stimulus are enhanced in patients with obstructive coronary artery disease. This response to a relatively mild sympathetic stress, reproducible by a variety of analogous stressful situations during daily life, could present an increased risk for acute cardiac events.