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Interactive effects of ST-T wave abnormalities on survival of patients with coronary artery disease
J H Crenshaw1, D M Mirvis, F el-Zeky
1Medical Service, Veterans Affairs Medical Center, Memphis, Tennessee.
Insights
Electrocardiographic ST-T wave abnormalities are linked to reduced survival in patients with mild coronary artery disease, but not severe or no disease. The impact of ST-T changes on survival depends on coronary artery disease severity.
Area of Science:
- Cardiology
- Clinical Medicine
- Diagnostic Electrocardiography
Background:
- Previous research indicates a correlation between electrocardiographic (ECG) ST-T wave abnormalities and decreased patient survival.
- The clinical, hemodynamic, and angiographic factors associated with this observation require further elucidation.
Purpose of the Study:
- To investigate the clinical, hemodynamic, and angiographic correlates of ST-T wave abnormalities.
- To determine the independent impact of ST-T abnormalities on survival based on coronary artery disease severity.
Main Methods:
- Analysis of data from 9,731 patients who underwent cardiac catheterization between 1976 and 1986.
- Categorization of patients into groups based on coronary artery obstruction severity: severe (>70%), mild (10-69%), and no obstruction.
- Application of stepwise regression analysis to identify independent predictors of 5-year survival within each group.
Main Results:
- Patients with ST-T abnormalities exhibited more clinical risk factors and greater left ventricular dysfunction.
- Survival time was significantly reduced in patients with ST-T abnormalities and either severe or mild coronary artery disease.
- ST-T abnormalities were not an independent predictor of survival in patients with severe or no coronary artery disease, but were in those with mild disease.
Conclusions:
- The prognostic significance of electrocardiographic ST-T wave abnormalities is contingent upon the severity of underlying coronary artery disease.
- ST-T abnormalities are an independent predictor of reduced survival specifically in patients with mild coronary artery disease.
Abstract:
Previous studies have documented a reduced survival time in patients with an electrocardiographic (ECG) ST-T wave abnormality. This study was designed to determine the clinical, hemodynamic and angiographic correlates of this observation. Data from 9,731 patients undergoing cardiac catheterization from 1976 through 1986 were analyzed; 5,531 had severe (greater than 70%) obstruction of at least one major coronary artery, 1,706 had mild (10 to 69%) obstruction and 2,494 had no obstruction. Of the patients with severe obstruction, 2,536 were treated medically and 2,995 were treated by surgical revascularization. Patients with an ST-T abnormality had more clinical risk factors (including older age and greater prevalence of diabetes mellitus, hypertension and prior myocardial infarction) and greater left ventricular dysfunction (including higher end-diastolic pressure and ventricular volume, reduced ejection fraction and greater prevalence of contraction abnormality) than did those without this ECG pattern. Survival time was significantly (p less than 0.01) reduced in subsets of patients with an ST-T abnormality and with severe or mild coronary artery disease; in those without coronary disease, ST-T changes did not correlate with reduced survival. Stepwise regression analysis was applied to each group to determine the independent predictors of 5-year survival. In patients with severe disease or no disease, an ST-T abnormality was not chosen as an independent predictor of 5-year survival; in the group with mild disease, ST-T changes were an independent predictor of reduced survival. Thus, the independent impact of an ST-T abnormality on survival is dependent on the severity of underlying coronary artery disease.