CORRELATION BETWEEN ISOLATED NEGATIVE U-WAVES AND THE GRADE OF CORONARY-ARTERY SPASM

The relation between isolated negative U waves and the severity of ind uced coronary artery spasm was investigated in 24 patients with varian t angina to determine the grade of myocardial ischemia during the appe arance of isolated negative U waves, Coronary artery spasm was induced by injections of either incremental doses of acetylcholine or ergonov ine into the left coronary artery. Coronary spasm was quantified into 4 grades: Grade 0=complete perfusion, Grade 1=partial perfusion, Grade 2=penetration without perfusion, and Grade 3=no perfusion. Induction with acetylcholine was discontinued when a coronary spasm of Grade gre ater than or equal to 2 was induced. Electrocardiogram in leads V1 to V6 and systemic blood pressure were recorded continuously. Provocation s of coronary spasm with at least 2 doses of acetylcholine could be pe rformed in 15 patients. All acetylcholine-induced coronary spasms of G rade less than or equal to 1 disappeared spontaneously within 3 min. N egative U waves developed in 19 (79%) patients, in whom 37 trials with acetylcholine or ergonovine injection were performed. Isolated negati ve U waves were detected in 10 trials, negative U waves and ST depress ion in 8 trials, and negative U waves and ST elevation in 14 trials. T he induced coronary spasms associated with isolated negative U waves w ere of Grade 1 in 9 of the 10 trials. In contrast, all of the coronary spasms associated with negative U waves and ST elevation had a Grade of greater than or equal to 2. In conclusion, the coronary angiographi c finding associated with isolated negative U waves is coronary spasm with delayed filling of the distal coronary artery, with opacification of the entire coronary bed.