Circadian variation in variant angina

Thirteen hospitalized patients with variant angina were studied to assess circadian variation in disease activity. Over 48 hours, all angina attacks were noted, a continuous Holter electrocardiogram was recorded and 2 ergonovine tests were performed 12 hours apart, 1 at 4 am and the other at 4 pm. Only 2 patients gave a clearcut history of more frequent nocturnal or early morning attacks. During the study period, 1.8 ± 1.6 am and 0.62 ± 1.2 pm angina episodes per patient were reported (p < 0.02), but a circadian pattern was apparent in only 4 patients. However, Holter analysis revealed 5.3 ± 13.8 am and 2.6 ± 8.5 pm episodes of ST elevation per patient (p < 0.05) and 8.1 ± 13.9 am and 3.2 ± 8.5 pm episodes of ST elevation, ST depression or T-wave pseudonormalization (p < 0.01). Ten of 11 patients with Holter abnormalities had more frequent am than pm attacks (p < 0.01). ST elevation developed during all 13 of the 4-AM and 12 of 13 of the 4-PM ergonovine tests. In 10 cases the ergonovine threshold at which the attack occurred was lower in the morning, in no case was it lower in the afternoon, and in 3 patients the morning and afternoon doses were identical (p < 0.01). Thus, circadian variation in disease activity both for spontaneous and provoked attacks is present in most patients with variant angina, even though it is often not clinically apparent.