Plasma renin activity in the emergency department and its independent association with acute myocardial infarction

Elevated plasma renin activity (PRA) is associated with increased risk of future myocardial infarction (MI) in ambulatory hypertensive patients. The present study evaluated the relationship of PRA to the diagnosis of acute MI in patients presenting to an emergency department with suspected acute MI. PRA was measured upon entry to the emergency department, before any acute treatment, as part of the standard evaluation of 349 consecutive patients who were hospitalized for suspected MI. Diagnosis of acute MI was confirmed in 73 patients, and ruled out in 276. They did not differ in age (65.9 ± 2 v 66.1 ± 1 years), systolic (143 ± 4 v 140 ± 2 mm Hg), or diastolic (81 ± 2 v 81 ± 1 mm Hg) pressures. Median PRA was 2.7-fold higher in acute MI (0.89 v 0.33 ng/L/s; P< .001). In a multivariate analysis controlling for other cardiac risk factors and prior drug therapy, PRA as a continuous variable was the predominant independent factor associated with acute MI (P< .0001), followed by white race (P= .002) and history of hypertension (P= .047). The height of the PRA level upon entry to the emergency department was directly and independently associated with the diagnosis of acute MI. These new findings extend earlier reports because they encompass acute MI patients, include both hypertensive and normotensive patients, and control for potentially confounding variables. Based on these observations, a randomized clinical trial is warranted to determine whether measurement of PRA in acute MI could refine the process by which treatments are applied.