"Ischemic" heart disease in fire fighters with normal coronary arteries

Near maximal stress testing conducted on a group (N = 90) of randomly selected Los Angeles City fire fighters (age 40-59 yrs.) revealed that 10% had ischemic ECG changes. These ischemic ECG responses were confirmed during a second test conducted two to four weeks after the initial test. Coronary heart disease (CHD) risk factor analysis revealed that in general the men were not at high risk for CHD. Six of the nine men elected to undergo cardiac catheterization and angiography. One patient had severe triple vessel disease and subsequently underwent aorto-coronary bypass surgery. Another had 50% obstruction in the circumflex branch of the left coronary while the other four men had no visable signs of coronary obstruction. The men with "normal" coronaries, however, did show signs of abnormal cardiac function during atrial pacing. One man had cardiac enlargement, hypokinesis, ischemic ECG and abnormal lactate metabolism. Another had abnormal lactate metabolism and ischemic ECG. A third man had moderate cardiac enlargement with anterior wall hypokinesis. The fourth had ischemic ECG changes with angina but otherwise normal cardiac function. All four of these men had pressures which were within normal limits. These data show that some fire fighters have "ischemic" heart disease with patent coronary arteries. This disease may be due to job related factors (i.e. carbon monoxide and other noxious fumes, catecholamines, etc.) which reduce myocardial oxygen supply or greatly increase myocardial oxygen demands.