Morning increase in ambulatory ischemia in patients with stable coronary artery disease. Importance of physical activity and increased cardiac demand

J D Parker, M A Testa, A H Jimenez, G H Tofler, J E Muller, J O Parker, P H Stone
1994 Circulation  
The morning increase in asymptomatic ambulatory ischemia may be due to heightened coronary tone, increased physical activity, or both. If ambulatory ischemia is primarily due to physical activity, then alterations in the schedule of physical activity should be reflected in a corresponding alteration in the occurrence of ischemia. This study was designed to examine the relation between activity patterns and the frequency of ambulatory ischemic episodes and the effect of nadolol on these
more » ... l on these relations. Methods and Results A double-blind, randomized, placebocontrolled, crossover trial of nadolol versus placebo was performed in 20 patients with stable coronary artery disease. At the end of each 2-week treatment phase, patients were hospitalized for 48 hours. In the hospital, there was a regular activity day (awaken and assume normal activities at 8:00 AM) and a delayed activity day (awaken at 8:00 AM, arise at 10:00 AM, and begin normal activity at noon). Ambulatory ECG monitoring was performed throughout the hospitalization. On the regular activity day, there was a morning increase in heart rate and in the number of ischemic episodes during therapy with placebo that began at 8:00 AM. In contrast, on the delayed activity day, there was a 4-hour phase shift of the increases in heart rate and the increase in ischemic episodes (ie, at noon) corresponding to the onset of physical activities. Therapy with nadolol caused a 50% reduction in the total number of
doi:10.1161/01.cir.89.2.604 pmid:8313548 fatcat:tcghmby6nvee7nwhy2fkahd3da