The extremely prominent negative U wave occasionally appears during a cardiac attack in variant angina pectoris. The clinical profile of the negative U wave was therefore studied in 80 patients with variant angina pectoris (VA) and 33 controls with resting angina pectoris (RA). The prominent negative U wave appeared in 55 of the patients with VA (68.8% of patients) and in 10 of the patients with RA (30.3%); thus, there was a significant difference in the appearance of the wave between the 2 groups of patients (p<0.001). The leads in which the negative U wave appeared were mostly consistent with those in which the ST segment was elevated. The negative U wave began to appear at about the time when ST-segment elevation began to improve; the wave then gradually became very prominent and then eventually disappeared. The patients with VA and also those with RA on whose ECGs the negative U wave appeared during exercise testing also had negative U waves during spontaneous episodes of angina. An investigation of the frequency of appearance of ST deviation and negative U waves during exercise testing, regardless of the type of angina pectoris, disclosed that the negative U wave appeared in 14 of 20 patients with ST-segment elevation (70% of patients), while the negative U wave appeared in only 52 of 519 patients with either no ST change or ST-segment depression (10.4%); thus, there was a significant difference in the appearance of the negative U wave between these 2 groups (p<0.001). Coronary cinearteriography failed to disclose any apparent difference between the appearance of the negative U wave and the presence of stenosis. The prognosis of VA and RA in patients with negative U waves was less favorable compared to those without negative U waves. In particular, we noted that of the 10 patients with RA associated with negative U waves, 4 died. Al-From the
SUMMARYIn order to clarify the clinical significance of a persistent negative U wave in patients with myocardial infarction, the clinical features and prognosis of a group of such patients were compared with a group without negative U waves. The persistent negative U wave was defined as the presence of a negative U wave at the time of discharge. The subjects were classified into 2 groups: group A-55 patients (50 males and 5 females, 5910 years) with negative U waves; group B-70 patients (55 males and 15 females, 619 years) without negative U waves. The average follow-up periods were 4921 months in group A and 4218 months in group B. Negative U waves appeared in leads where r or R waves were present, but were not observed in leads with a QS pattern. The incidences of a diseased left anterior descending artery, multi-vessel disease, left ventricular wall motion abnormality and left ventricular ejection fraction below 50% were higher in group A than in group B. The recurrence of myocardial infarction was 18.2% in group A and 7.1% in group B, and the number of patients treated with antianginal drugs was higher in group A than in group B. The rate of recurrence of myocardial infarction at 1, 3 and 5 years was 6%, 17% and 26%, respectively in group A and 6%, 8% and 11%, respectively in group B. Thus, it was concluded that patients in group A require more active treatment than those in group B.
Additional Indexing Words: Recurrent myocardial infarctionClinical course of myocardial infarction Aortocoronary bypass graft Mechanism of negative U wave Genesis of U wave
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