Multicenter Prospective Analysis of a Descriptive Classification of ECG at Admission and During Evolution of the Acute Myocardial Infarction

pp 151-162

Abstract

The presence and type of repolarization abnormalities are widely accepted criteria for the initial management of acute myocardial infarction (AMI) but they can be insufficient for further risk assessment in the evolving phase.

Objective

To evaluate prospectively a classification of ECG at admission to the CCU (ECGa) and to correlate these findings with those of the ECG during evolution (ECGe) and clinical outcome.

Methods

Four hundred fifty one patients drawn from a national survey on AMI (SAC'96). The ECGaa(<_2h) were classified as: ST segment elevation (STT), negative Twave (T-), ST depression (STI), normal(N) and other (0) changes. The ECGe 224 h) were classified in Q-wave AMI and non-Q wave AMI subdivided in subendocardial or ST, type T (negative T waves) and indetermined (without ECG changes). Combined event (CE) at discharge of CCU was defined as: death (D) and heart failure (HF).

Results * p< 0.001; ** p < 0.05.

_{ECG admission                         ECG during evolution (224 hours)}

                       _{Subendocardial     Q-wave    Negative T-   Indetermined}

                                                                              _wave

_{ST1 358 (79%)    5(1.4)                   325(91)       23(6.2)               50.4)}

_{STI. 47 (10%)       33(70)                    6(13)            5(11)                3(6)}

_{T- 27 (6%)              0                            4(15)            21(78)             2(7)}

_{N 4 (1%)                 0                            1(25)            2(50)               1(25)}

_{0 150%)                  0                             2(13)           1(7)                 12(80)}   Four percent of Q-wave AMI (13/338) did not evidence STT in the ECG a and one third of non Q-wave AMIs in the ECGe (33/113) evidenced STT in the ECGa. The patients with STT were younger (60 ± 13 years versus 71 ± 13 years*), had less history of prior infarction (11 versus 23.5%), chronic angina (14.5 versus 40%*), HF (2 versus 16%*) and CE (37.5versus 45%) compared to those with ST.L. Patients with STT received thrombolytics in 61% of cases; successful reperfusion was associated with more non-Q wave AMI (12 versus 2.5%**). Persistence of ST.. in the ECGe (70% of cases) was a marker of higher incidence of death (16 versus 8%) and combined event (54.5 versus 21%, OR = 4.4/0.9-28; p =0.07) compared to those patients that resolved theST.L. Conclusions 1) The descriptive classification of the ECG at admission identifies patients with a different risk profile. 2) AMI with persistent ST.- during CCU stay evidence a higher risk of death and heart failure. 3) Non-Q wave infarctions come from differ-ent patterns of admission ECG.