PLASMA ATRIAL-NATRIURETIC-FACTOR LEVELS, IMPAIRED MYOCARDIAL-CONTRACTILITY AND PAIN INTENSITY IN UNCOMPLICATED ACUTE MYOCARDIAL-INFARCTION

To investigate the relationship between plasma atrial natriuretic fact or (ANF) levels, impaired myocardial contractility and pain intensity in acute myocardial infarction (AMI) we introduced a procedure estimat ing the pain component not influenced by the individual emotional reac tion to stress, i,e,, the original pain sensation, We deduced this pai n component during AMI by correcting the personal report of AMI pain, quantified on a VAS, with the emotional reaction of each patient estim ated by using a custom-built instrument which applies electrical stimu li of different intensities. Twenty-five patients with uncomplicated A MI were studied. According to plasma ANF levels and AMI pain values re ported on the VAS, patients were categorized into 2 groups: pain and n o-pain, Plasma ANF Levels were significantly lower in pain (35.9 +/- 2 .5 pg/ml) than in no-pain patients (70.8 +/- 3.3 pg/ml), whereas the e jection fraction (EF) was significantly higher in pain (49.6 +/- 1.7%) than in no-pain patients (29.3 +/- 1.9%). Within each group, a negati ve correlation was found between ANF and EF; the corresponding regress ion lines did not differ significantly in their dopes or intercepts, s uggesting that AMI pain does not affect ANF release. The significant n egative correlation between original pain sensation and EF found in pa in patients indicates that this pain component may be useful to gauge the severity of impaired myocardial contractility during AMI. Moreover , the much higher plasma ANF levels observed in no-pain patients sugge st that ANF may be involved in preventing AMI pain.