Outcome in myocardial infarction is related to the morphologic pattern of ST elevation

Purpose

Although invasive management of ST-segment elevation myocardial infarction (STEMI) has improved the clinical outcome, early mortality remains an important issue. Our purpose is to assess the utility of the initial electrocardiographic (ECG) pattern in detecting patients who are at increased risk despite the current recommendations of revascularization.

Methods

We analyzed 446 consecutive patients (age 61.9 ± 13.8 years, 76.5% male) admitted in the first 12 hours of STEMI to our coronary unit. Exclusion criteria were left bundle branch block at admission or previous myocardial infarction. Most patients (87%) were treated with primary angioplasty. Patients treated with thrombolytics and with early reperfusion criteria were programmed to coronary angiography the following day. Two groups were defined according to the presence of ST-segment elevation (STE) together with distortion of the terminal portion of the QRS in two or more adjacent leads (group 1) or the absence of this pattern (group 2) (Figure 1).

Figure 1

Results

There were 102 (22.8%) patients in group 1 and 344 (77.2%) in group 2. No differences in age or risk factors were seen between both groups. The number of diseased vessels was similar. Group 1 had higher CK, MB-CK and cardiac troponin I. The maximal Killip class was >2 during hospitalisation in 38% of group 1 vs 24% (P = 0.009). Group 1 had more mortality (8.8% vs 2.6%, P = 0.005) and more cardiogenic shock. Other ECG characteristics related to mortality were the sum of STE in all leads, the number of leads with STE and ST segment depression. After a logistic regression analysis including all ECG characteristics, the pattern of group 1 remained significantly related to mortality (P = 0.013) together with the number of leads with STE.

Conclusion

The initial STE pattern is useful in detecting patients at higher risk of death or cardiogenic shock, despite the adequate revascularization therapy in STEMI.