Clinical study
Value of the electrocardiogram in predicting left ventricular enlargement and dysfunction after myocardial infarction

https://doi.org/10.1016/S0002-9343(02)01424-9Get rights and content

Abstract

Purpose

To identify electrocardiographic predictors of left ventricular enlargement or persistent dysfunction following a myocardial infarction.

Methods

Baseline and predischarge 12-lead electrocardiograms (ECGs) from 272 patients with anterior myocardial infarction who were enrolled in the Healing and Early Afterload Reducing Therapy trial were evaluated and related to echocardiographic data obtained at baseline and day 90. ST-segment elevation, QRS score, and number of negative T waves were assessed at both time points. The majority of patients (87%; n = 237) received reperfusion therapy. Multivariate models were used to adjust for potential confounders, including maximal creatine kinase level and ejection fraction at baseline.

Results

None of the baseline electrocardiographic variables independently predicted ventricular enlargement or recovery of function. In contrast, the sum of ST- and maximum ST-segment elevation, and the number of leads with ST-segment elevation ≥1 mm in the predischarge ECG, were independent predictors of ventricular enlargement from baseline to day 90. Each lead with ST-segment elevation ≥1 mm was associated with 3.5 mL of ventricular enlargement (95% confidence interval [CI]: 1.6 to 5.5 mL; P <0.0001). Similarly, the sum of ST-segment elevation (odds ratio [OR] = 0.78; 95% CI: 0.69 to 0.89; P <0.0001), the maximum ST-segment elevation (OR = 0.25; 95% CI: 0.13 to 0.45; P <0.0001), and the number of leads with ST-segment elevation ≥1 mm (OR = 0.58; 95% CI: 0.45 to 0.74; P <0.0001) were independently associated with a lower likelihood of recovery of function at day 90.

Conclusion

Predischarge ECG may be a useful tool for early identification of patients at risk of ventricular enlargement and persistent dysfunction following myocardial infarction.

Section snippets

Patients

The study enrolled 352 patients with anterior Q-wave myocardial infarction. Patients were randomly assigned to receive one of three treatments: placebo for 14 days, followed by full-dose (10-mg) ramipril; low-dose (0.625-mg) ramipril for 90 days; or full-dose ramipril for 90 days. Patients with left bundle branch block were excluded from enrollment. Electrocardiography was performed within 24 hours (baseline ECG) and before discharge (predischarge ECG) after myocardial infarction.

Results

There were few differences between those patients included and not included in the ECG cohort (Table 1). From baseline to day 90, there was overall improvement in left ventricular ejection fraction (52% ± 10% to 57% ± 9%; P <0.0001), reduction in infarct segment length (26% ± 11% to 16% ± 14%; P <0.0001), and small increases in left ventricular end-diastolic volume (104 ± 36 mL to 108 ± 38 mL; P <0.01).

Recovery of left ventricular function

All of the predischarge electrocardiographic variables differed significantly when those who recovered left ventricular function were compared with those who did not (Table 5). There were significant differences in ST-segment elevation between recoverers and nonrecoverers for each lead from V1 to V5 (P <0.02). The sum of ST-segment elevation, the maximum ST-segment elevation, the number of leads with ST-segment elevation ≥1 mm, the number of negative T waves, and the QRS score were all

Discussion

We found that assessment of ST-segment elevation on an ECG before discharge after anterior myocardial infarction can identify patients who are at increased risk of ventricular enlargement and dysfunction. In particular, residual ST-segment elevation at hospital discharge, a median of 7 days from the onset of symptoms, was an independent predictor of progressive left ventricular enlargement (remodeling) and persistent dysfunction (lack of functional recovery) following myocardial infarction.

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