Neuroendocrine activation and markers of early reperfusion in the acute phase of myocardial infarction

Potentially harmful stimulation of the neuroendocrine axis occurs in the early hours of myocardial infarction. It has been suggested that this acute neuroendocrine response might be attentuated by early therapeutic reperfusion. To test this hypothesis we measured plasma concentrations of atrial natriuretic factor (ANF), renin adrenaline (ADR) and noradrenaline (NADR) on admission and at 1 h and 4 h in 32 patients undergoing streptokinase treatment within 6 h of myocardial infarction. Fractional changes (FC) in hormone levels were calculated: e.g. ANFO-ANF4/ANFO. Resolution of ST segment elevation at 4 h was the primary measure of reperfusion. Sixteen patients showed ST segment resolution. There was no difference in hormone levels at baseline between reperfused and non-reperfused patients. Fractional changes in ANF, renin and ADR were similar in both groups. NADR fell from admission to 4 h in reperfused patients but rose in nonreperfused (FC 0.28 vs 0.10; P = 0.054). There was no difference in the changes in pulse rate or blood pressure from admission to 4 h between the two groups. Thus there is no evidence that early reperfusion acutely alters the release of ANF, renin or ADR to myocardial infarction. Although plasma NADR tended to fall acutely in reperfused patients this was not accompanied by other markers of sympathetic withdrawal.