Abstract
Background
Generally considered as benign, ECG early repolarization (ER) pattern was recently claimed to be an indicator of increased susceptibility to fatal arrhythmias during acute ischemia. The victims of sudden cardiac death have been reported to have high prevalence of ER comparing with survivors of acute coronary event.
We aimed to test the association between the ER pattern on resting ECG recorded prior to ST-elevation myocardial infarction (STEMI) and the risk of ventricular fibrillation (VF) during acute phase of STEMI in non-selected population of STEMI patients.
Methods
For STEMI patients admitted to a tertiary care hospital for primary PCI during 2007–2010 (n=2286), all ECGs recorded prior to the date of admission with STEMI were extracted from a digital archive. The latest ECG recorded prior to the index STEMI was used for analysis.
After excluding ECGs with paced rhythm and intraventricular blocks with QRS duration ≥120ms, the remaining ECGs were processed using the Glasgow algorithm allowing automatic ER detection. The association between ER-pattern on historical ECG and VF during the first 48 hours of STEMI was tested using logistic regression.
Results
Historical ECGs were available for 1584 patients; 124 of them were excluded due to a paced rhythm or wide QRS, leaving 1460 patients available for analysis (age 68±12 years, 67% male). The time from historical ECG to STEMI was 16 (IQR 4–49) months. ER pattern was present on historical ECG in 272 of 1460 (18.6%) (ER+ group), among them in 90 (33%) – in inferior leads, in 116 (43%) – in lateral leads, in 66 (24%) – both in inferior and lateral leads.
ER+ patients were younger both at the time of historical ECG (64±13 vs 66±19; p=0.041) and at the time of STEMI (67±12 vs 68±12; p=0.033), and had lower heart rate on historical ECG (68±12 vs 73±15; p<0.001) than ER- patients. ER+ and ER- groups did not differ regarding clinical characteristics and conventional ECG measurements. The course of STEMI was complicated by VF in 106 patients (17 of them from ER+ group). The occurrence of VF during STEMI was not associated with ER-pattern on historical ECG (OR 0.875 95% CI 0.518–1.479; p=0.618). There was no association of ER pattern with VF before reperfusion (OR 0.54 95% CI 0.25–1.21; p=0.135) or reperfusion VF (OR 1.28 95% CI 0.55–3.01; p=0.569). No association was observed with regard to localization (inferior or lateral) of ER-pattern either.
Conclusion
In a non-selected population of STEMI patients the presence of ER-pattern on ECG recorded prior to the acute coronary event was not associated with VF during the first 48 hours of STEMI.
THE HIGH PREVALENCE AND CLINICAL IMPLICATION OF MYOCARDIAL BRIDGING IN PATIENTS WITH EARLY REPOLARIZATION PATTERN
