Plasma proatrial natriuretic factor (1-98) concentration after myocardial infarction: relation to indices of cardiac and renal function.

OBJECTIVES: (a) To assess the relation between plasma concentrations of proatrial natriuretic factor (1-98) and non-invasively derived indices of left ventricular systolic and diastolic performance and (b) to assess the potential confounding effect of renal function and age on this relation in patients with acute myocardial infarction.
DESIGN: Cross sectional comparison of biochemical and echocardiographic indices of cardiac function.
SETTING: Norwegian central hospital. PATIENTS: Sixty four patients with acute myocardial infarction. MAIN OUTCOME MEASURES: Relation between plasma proatrial natriuretic factor (1-98) concentrations and echocardiographic indices of left ventricular systolic function as assessed by univariate and multivariate linear regression analysis. Sensitivity and specificity of plasma proatrial natriuretic factor (1-98) concentration as a measure of left ventricular systolic and diastolic dysfunction.
RESULTS: Plasma proatrial natriuretic factor (1-98) concentrations were significantly related to left ventricular ejection fraction (r = -0.33; P = 0.008), age (r = 0.43; P < 0.001), and creatinine clearance (r = - 0.53; P < 0.001). In a multivariate model left ventricular ejection fraction and creatinine clearance were both independently related to plasma values. The mean concentration of proatrial natriuretic factor (1-98) was significantly higher in patients with an ejection fraction of < 40% than in those with an ejection fraction of > or = 40% (1876 (1151) v 1174 (530) pmol/l; P = 0.03) and in patients with an abnormal transmitral E/A ratio ( < 0.65 or > 1.65, where E/A is ratio of peak early filling velocity to peak atrial component) compared with those with a normal ratio (1572 (895) v 1137 (523) pmol/l, respectively; P = 0.02). When patients were subdivided according to the median concentration of proatrial natriuretic factor (1192 pmol/l) the sensitivity and specificity were 89% and 56% respectively for detecting a left ventricular ejection fraction of < 40% and 75% and 61% respectively for detecting an abnormal E/A ratio. Concentrations below the median had a negative predictive value of 97% in excluding an ejection fraction of < 40% and of 84% in excluding an abnormal E/A ratio.
CONCLUSION: These results suggest that soon after myocardial infarction left ventricular ejection fraction and indices of renal function are independently related to plasma concentrations of proatrial natriuretic factor (1-98). Plasma concentrations of proatrial natriuretic factor (1-98) seem to reflect renal and cardiac performance rather than specific haemodynamic variables assessed by noninvasive methods. Plasma proatrial natriuretic factor (1-98) measurements may be a useful screening tool to identify patients with normal cardiac function soon after myocardial infarction.