Hamsters with coronary vasospasm are at increased risk from stress

Results of earlier experiments suggested that hamsters with inherited heart disease were at a higher risk of succumbing to stress during the vasospastic, lesion-forming period of their lives rather than later when the process of congestive heart failure had begun. To test this hypothesis, we stressed cardiomyopathic hamsters (CMH) whose ages differed by about 3 months; the younger of the two groups of stressed hamsters was in the vasospastic phase of the disease. The stressor was cold immobilization in which stressor intensity was manipulated using two durations of cold exposure. Log rank survival curves revealed no difference in mortality with the more intense stressor. However, significantly fewer of the older hamsters succumbed to the less intense stressor (46% as compared with 85% of the younger CMHs). Examination of the hearts in the experiment where mortality rate was the same for both groups revealed evidence of cardiac dilatation, indicative of heart failure, only in the older hamsters following stress. Since the younger hamsters did not show these changes and since they, but not the older animals, have coronary microvascular spasm and an increased susceptibility to stress, it would appear that the process of coronary vasospasm should be viewed as an independent and additional risk factor in determining the consequences of stress. Because of the effects of stress in the younger cardiomyopathic hamster, we believe that a neural link--which can be activated by stress--may be involved in the pathogenetic process of coronary vasospasm.