Automated electrocardiographic scores to estimate myocardial injury size during the course of acute myocardial infarction

Detection of proximal coronary occlusion in acute coronary syndrome: a feasibility study using computerized electrocardiographic analysis

BACKGROUND

Rapid identification of a proximal occlusion site of a major coronary artery is of paramount importance in the care of myocardial infarction (MI). It is increasingly recognized that routine electrocardiogram (ECG) can be used for that purpose, provided that expert interpretation is available. Computer-based signal analysis has potential to enhance early ECG interpretation but its performance must be validated against manual algorithms. We therefore set out to develop a computer-assisted model to detect proximal occlusion of the left anterior descending coronary artery (LAD) in patients with suspected acute coronary syndrome (ACS).

METHODS

Based on manual anatomical interpretation of the ECG, obtained from 216 consecutive patients who were admitted due to suspected ACS, an automatic computerized ECG model to detect LAD occlusion was constructed. Agreement between manual evaluation of the ECG by two cardiologists and a computerized ECG algorithm to detect occlusion of the LAD and the site of occlusion was determined.

RESULTS

Using an expert electrocardiographer's anatomical interpretation as the gold standard, the computer model recognized patients fulfilling ECG criteria for any occlusion of the LAD with a specificity of 99% and a sensitivity of 67% (kappa= 0.71). However, proximal LAD occlusion was detected with 100% specificity and 86% sensitivity (kappa= 0.72). The computer program detected a distal occlusion in the LAD with a specificity of 99% and a sensitivity of 40% (kappa= 0.72).

CONCLUSIONS

Computerized anatomical interpretation of the ECG is feasible and allows detection of a proximal LAD occlusion with excellent accuracy.

Comparative accuracy of manual versus computerized electrocardiographic measurement of J-, ST- and T-wave deviations in patients with acute coronary syndrome

Accurate and rapid electrocardiographic interpretation is of crucial importance in acute coronary syndrome (ACS). Computerized electrocardiographic algorithms are often used in out-of-hospital settings. Their accuracy should be carefully validated in ACS, particularly in ST-elevation myocardial infarction. This study evaluated the comparative accuracy of lead-specific computer-based versus manual measurements of the J-point, ST-segment, and T-wave deviations in standard 12-lead electrocardiograms (ECGs) (excluding lead aVR). Sixty-nine consecutive patients with suspected ACS were included. The interobserver reliability in the determination of ST-segment deviation>or=0.2 mV in leads V2 and V3 was very good (kappa=0.94 and 0.93, respectively). Agreement between a cardiologist and the computer regarding ST elevation>or=0.2 mV in lead V2 was moderate (kappa=0.72) and in V3 was very good (kappa=0.85). For ST depression or elevation>or=0.05 mV in lead LIII, agreement was good and moderate (kappa=0.79 and 0.51, respectively). Bland-Altman analysis demonstrated clinically acceptable limits of agreement comparing measurements of the J point and the T wave, but clinically inadequate limits of agreement with respect to ST-segment deviation, between the electrocardiographer and the computer. The optimal cut-off points were 0.115 mV (sensitivity 89%, specificity 98%) for the computer program to detect ST elevation>or=0.2 mV and 0.045 mV (sensitivity 74%, specificity 99%) for revealing ST elevation>or=0.1 mV. It was found that automatically measured ST-segment deviations were smaller than those manually measured. In conclusion, a correction should be performed to obtain optimal results in the automated analysis of ECGs, because the results have important implications for clinical decision making.

Clinical value of 12-lead electrocardiography to predict the long-term prognosis of GISSI-1 patients

OBJECTIVES

We evaluated the prognostic relevance of the extent of myocardial injury, as measured by a standard electrocardiographic (ECG) method, on the patients' long-term prognosis, its time dependence and its relation to fibrinolytic therapy efficacy.

BACKGROUND

Many clinical and instrumental variables influence the short- and long-term prognoses of patients with acute myocardial infarction (MI). The extent of myocardial injury is relevant to predict both the short-term prognosis and the benefit of fibrinolytic treatment.

METHODS

In 8,731 patients with MI enrolled in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto (GISSI-1) study, the number of ECG leads with ST-segment elevation was used to define the extent of myocardial injury and four different severity groups: A, B, C and D, with ST-segment elevation in two or three leads, four or five leads, six or seven leads and more than eight leads, respectively.

RESULTS

At 10 years, the mortality rates were 36.6%, 41.0%, 47.9% and 51.2% in groups A, B, C and D, respectively. At 30 days, according to the extent of myocardial injury, the relative risk (RR) of death was significantly higher for groups B, C and D, compared with group A (RR 1.19 and 95% confidence interval [CI] 1.06 to 1.34 for group B; RR 1.54 and 95% CI 1.31 to 1.80 for group C; RR 2.01 and 95% CI 1.69 to 2.39 for group D). At one-year follow-up, the RR of death remained higher for groups C and D, whereas, subsequently, the extent of myocardial injury did not influence the RR of death. At 10 years, the differences in fibrinolytic treatment benefit between the four groups were similar to those at hospital discharge.

CONCLUSIONS

At 10 years, the survival rate appears to be related to the extent of myocardial injury, as evaluated by ST-segment elevation on the admission ECG.

Cardiac decompensation during an ischemic event weakens the predictive power of myocardial injury markers

Our objection was to find determinants of long-term outcome in routine data collected for differential diagnosis of suspected acute myocardial infarction. Study population consisted of 263 discharged patients who were initially hospitalized for differential diagnosis of suspected acute myocardial infarction between October 1992 and January 1993. Follow-up time for all cause and cardiac mortality was 5 years. The variables studied as predictors of outcome were computerized ECG, peak creatine kinase isoenzyme MB, peak troponin I, radiographic evidence of pulmonary congestion (cardiac decompensation), treatment for hyperlipidemia, hypertension or diabetes, smoking, previous myocardial infarction, age and gender. Total mortality was 32% at 5 years, of which 77% (64/83) was of cardiac origin. Pulmonary congestion in chest X-ray was the most powerful predictor of outcome (RR=3.3, 95% CI=2.0-5.2, P<0.001). In multivariate analysis congestion (RR=3.3, CI=2.0-5.2) was the only independent predictor of 5-year total mortality in addition to age (RR=1.06, CI=1.04-1.08). These two variables together with previous myocardial infarction (RR=1.9, CI=1.2-3.1) and hyperlipidemia (RR=2. 0, CI=1.1-3.5) were independent predictors of cardiac mortality. Radiographic evidence of cardiac decompensation during hospitalization is a strong and independent predictor of long-term outcome in unselected patients with suspected AMI. The predictive power of cardiac markers is confined to patients without pulmonary congestion.