ST segment monitoring before, three weeks and six months after aortocoronary bypass surgery.

ST segment monitoring by Holter ECG was conducted in 80 consecutive patients 2-4 weeks before aortocoronary bypass surgery and three weeks and six months after surgery. Preoperatively, all patients were under maximal medical therapy. In 31 out of 80 patients medical therapy could be stopped and thus 24-h ST monitoring could also be conducted without medication. Preoperative and early postoperative (three weeks) examinations were performed under hospital conditions. At 6 months after surgery the patients were monitored at home during their everyday activities. Twenty-eight per cent of patients waiting for aortocoronary bypass surgery under full medication showed transient ischaemic episodes in 24-h Holter ECG. Seventy-eight per cent of these episodes were asymptomatic. Without medication, 55% of patients had transient ischaemia. The exercise ECG data partly predicted the Holter ECG data. Patients with ST segment depression greater than 0.1 mV during exercise ECG had on Holter monitoring more and longer lasting ischaemic episodes than those with ST segment depression less than or equal to 0.1 mV. In patients with asymptomatic ST segment depression during exercise ECG the relation of silent episodes to symptomatic episodes on Holter monitoring was 5.3:1 while in patients with symptomatic ST segment depression during exercise ECG this relation was 2.3:1. Three weeks after operation the informative value of the Holter ECG was very restricted due to changes in the resting ECG caused by the operation and because patients do not exert themselves much at this time. Six months after surgery, Holter ECG is more informative, especially when conducted at home.(ABSTRACT TRUNCATED AT 250 WORDS)