Atrial natriuretic peptide levels after different types of inferior wall myocardial infarction

Background: Atrial natriuretic peptide (ANP) is released from cardiac atrium secondary to increased atrial pressure. The plasma levels;of ANP have been found to be related to short- and long-term prognosis after acute myocardial infarction (MI). The purpose of the present study was to investigate the plasma levels of ANP in three groups of patients with inferior wall acute MI classified according to ST-segment depression in the precordial leads. Methods: The study population consisted of 18 patients with inferior wall acute MI classified into three types: Type 1 = no precordial ST-segment depression (7 patients), Type 2 = sum of ST-segment depression in leads V-1 to V-3 equal to or more than the sum of ST-segment depression in leads V-4 to V-6 (4 patients), and Type 3 = maximal precordial ST-segment depression in leads V-4 to V-6 (7 patients). Results: Radioimmunoassay showed that plasma ANP levels were significantly higher in patients with Type 3 acute inferior wall myocardial infarction compared with those with Types I and 2 (313.1 +/- 233, 73.0 +/- 27.5), and 84 +/- 32.7 pg/ml, respectively, p = 0.018). Conclusions: Plasma ANP levels are higher in patients with Type 3 acute inferior wall MI compared with patients with Types 1 and 2. These findings, together with earlier ones, may contribute to our understanding of the pathophysiology of the presence of ST-segment depression in the precordial leads in inferior wall acute MI.