Prognostic utility of quantifying evolutionary ST-segment depression on early follow-up electrocardiogram in patients
Raymond T Yan1, Andrew T Yan, Kenneth W Mahaffey
1Canadian Heart Research Centre and Division of Cardiology, St Michael's Hospital, University of Toronto, 30 Bond Street, Room 6-034 Queen, Toronto, ON, Canada M5B 1W8.
Aims:
Although ST-segment depression (STD) on the admission electrocardiogram (ECG) confers adverse prognosis in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS), the implications of STD on follow-up ECG remain uncertain. We determined the prognostic significance of STD on follow-up ECG performed within 12-24 h of admission and whether its quantitative evaluation can further refine risk stratification.
Methods And Results:
The admission and follow-up ECGs of 3877 patients in the SYNERGY trial were analysed for the presence (>or=1 mm) and extent (maximum magnitude on any single lead) of STD. Of the 1110 patients presenting with STD on admission, 534 (48.1%) with persistent STD at follow-up had higher mortality at 30 days (7.1 vs. 3.6%, P = 0.01) and 6 months (10.7 vs. 5.2%, P = 0.001) than those with normalized STD. Among 2767 patients without STD on admission, 174 (6.3%) developed new STD on follow-up ECG and experienced increased mortality compared with those without such interval change (30 days: 4.0 vs. 1.7%, P = 0.035; 6 months: 8.0 vs. 3.3%, P = 0.001). After adjustment for established clinical prognosticators and the extent of STD on admission, every 1 mm increment of STD on the follow-up ECG independently predicted a graded increase in 30-day mortality [hazards ratio (HR) = 1.60, 95% confidence interval (CI) = 1.29-1.98, P < 0.0001], and death/myocardial infarction at 30 days (HR = 1.19, 95% CI = 1.03-1.36, P = 0.017) and 6 months (HR = 1.17, 95% CI = 1.03-1.32, P = 0.016).
Conclusion:
The magnitude of STD on a routine 12-24 h follow-up ECG provides incremental prognostic information beyond established clinical prognosticators and the extent of STD on admission. Incorporating a follow-up ECG and its quantitative evaluation for STD may further refine risk stratification of patients with NSTE-ACS.
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