Clinical significance of early vs late hypotensive blood pressure response to treadmill exercise.
BACKGROUND: It is generally believed that exercise-induced hypotension is the result of severe left-main or triple-vessel disease. Since this is not invariably so, and since most studies were performed in male populations, this study was done to determine the frequency of, and the significance of, exercise-induced hypotension in a more general population. METHODS: The treadmill exercise tests of 4850 consecutive patients performed at a university medical center over a period of 7.5 years were reviewed. To identify patients for further analysis, a hypotensive blood pressure response was initially defined (1) as a progressive fall in systolic blood pressure, (2) as a failure of the systolic blood pressure to rise more than 5 mm Hg during exercise, or (3) as an initial rise followed by a fall below the resting standing systolic blood pressure. RESULTS: The incidence of exercise-induced hypotension so defined was less than 2%. Exercise-induced hypotension occurred in two patterns. An early hypotension response was defined as a fall in systolic blood pressure of more than 10 mm Hg, associated with symptoms or ST-segment depression, during the first 5 minutes of exercise or as a progressive fall in systolic blood pressure of at least 20 mm Hg. The majority of patients (nine of 10) with an early hypotensive response had severe coronary artery disease. The late hypotension pattern was characterized by an initial rise, followed by a fall in the systolic blood pressure with continued exercise. Only half of the patients with this pattern had significant coronary artery disease, and half of the patients had other causes for exercise-induced hypotension. A late hypotensive response was six times more frequent than an early hypotensive response. CONCLUSIONS: This study identified two patterns of exercise-induced hypotension. Early, almost always due to severe coronary artery disease, and late, six times more common than early in which only half were due to coronary artery disease. Causes of a late hypotensive response to exercise that were not due to severe coronary artery disease included valvular heart disease, orthostatic hypotension, cardiomyopathy, idiopathic causes, and drugs. Drugs that contributed to a late exercise-induced hypotension response were diuretics, vasodilators, and negative inotropic agents.