Author + information
- Received November 8, 1995
- Revision received May 2, 1996
- Accepted May 7, 1996
- Published online October 1, 1996.
- MARCUS F STODDARD*
- ↵*Address for correspondence: Dr. Marcus F. Stoddard, Department of Medicine, Cardiology Division, University of Louisville, 550 South Jackson Street, Louisville, Kentucky 40202.
Objectives. This study sought to determine whether calcium antagonist, compared with nitroglycerin, administration attenuates left ventricular dysfunction after exercise-induced ischemia in humans.
Background. Exercise-induced ischemia impairs left ventricular systolic function and diastolic filling after exercise. The mechanism of this phenomenon is unknown but may relate to intracellular calcium overload.
Methods. Echocardiography was performed in 131 patients before and 30 min, 2 h and 4 h after exercise stress test. Ischemia was defined as a reversible thallium stress defect. No medication, sublingual nitroglycerin or nifedipine was randomly given to each patient at peak exercise.
Results. Isovolumetric relaxation time was significantly prolonged from rest (100 ± 19 ms [mean ± SD]) to 30 min (118 ± 20 ms, p < 0.0005), 2 h (117 ± 18 ms, p < 0.0005) and 4 h (110 ± 22 ms, p < 0.05) after exercise in 21 patients with exercise-induced ischemia who received no medication (ischemia-none group). Isovolumetric relaxation time similarly increased after exercise in 23 patients who received nitroglycerin and had exercise-induced ischemia (ischemia-NTG group) but was unchanged in 20 patients with exercise-induced ischemia who received nifedipine (ischemia-nifedipine group). Peak early filling velocity decreased in the ischemia-none and ischemia-NTG groups from rest to 30 min and 2 h after exercise, but peak early filling velocity was unchanged in the ischemia-nifedipine group. Ejection fraction decreased from rest to 30 min after exercise in the ischemia-none group (59 ± 12% vs. 51 ± 13%, p < 0.025) and ischemia-NTG group (59 ± 14% vs. 49 ± 14%, p < 0.005) but was unchanged in the ischemia-nifedipine group (50 ± 19% vs. 64 ± 18%, p = NS). A new regional left ventricular wall motion abnormality occurred more frequently 30 min after exercise in the ischemia-none group (11 [52%] of 21) and ischemia-NTG group (9 [39%] of 23) compared with the ischemia-nifedipine group (2 [10%] of 20, both p < 0.05). No change occurred in left ventricular systolic function and diastolic filling after exercise in the control groups.
Conclusions. Exercise-induced ischemia impairs systolic function and diastolic filling after exercise. Sublingual nifedipine but not nitroglycerin attenuates this process and suggests that altered calcium homeostasis may play a role in left ventricular dysfunction that occurs after exercise-induced ischemia.
- Received November 8, 1995.
- Revision received May 2, 1996.
- Accepted May 7, 1996.
- THE AMERICAN COLLEGE OF CARDIOLOGY