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Diagnosis

Identifying electrocardiographic left ventricular hypertrophy was problematic among patients with suspected acute cardiac ischemia

ACP J Club. 1995 May-June;122:75. doi:10.7326/ACPJC-1995-122-3-075


Source Citation

Larsen GC, Griffith JL, Beshansky JR, D'Agostino RB, Selker HP. Electrocardiographic left ventricular hypertrophy in patients with suspected acute cardiac ischemia: its influence on diagnosis, triage, and short-term prognosis: a multicenter study. J Gen Intern Med. 1994 Dec;9:666-73.


Abstract

Objective

To determine the short-term risks for patients presenting to the emergency department (ED) with cardiorespiratory symptoms and electrocardiographic left ventricular hypertrophy (ECG-LVH) and to compare the ECG interpretation by admitting physicians with that by experts.

Design

Blinded comparison of ECG interpretations by admitting physicians and expert reviewers (cardiologists and cardiology fellows) in an inception cohort of patients with in-hospital (admitted patients) or 48-hour follow-up (nonadmitted patients).

Setting

6 hospitals.

Patients

5768 patients (mean age, 66.5 y; 3278 men) who presented to the ED with suspected acute cardiac ischemia as determined by the Imminent Myocardial Infarction Rotterdam Study criteria. Follow-up was 89%.

Description of Test and Diagnostic Standard

Admitting physicians and expert reviewers used identical forms to independently evaluate each ECG for the presence or absence of QRS, ST-segment, or T-wave abnormalities; heart block; premature atrial and ventricular beats; tachyarrhythmias and bradyarrhythmias; and increased QRS voltage. Patients were categorized for the presence or absence of LVH on the basis of the Romhilt-Estes criteria. Final diagnosis was based on an independent review of clinical information.

Main Outcome Measures

Predictive value of ECG-LVH for cardiac ischemia and the sensitivity and specificity of the assessments by ED admitting physicians in identifying ECG-LVH.

Main Results

Patients with ECG-LVH were less likely to have acute myocardial in-farction (MI) than patients who did not have LVH but had primary ST-segment and T-wave abnormalities (11.9% vs. 48.4%; P < 0.001) or oth-er ECG abnormalities (11.9% vs. 16.4%; P = 0.02). Similar results were observed for the diagnosis of new unstable angina (P < 0.001 for both comparisons). The groups did not differ for mortality (7.5% vs. 10.6% vs. 5.1%). Patients with ECG-LVH were more likely to have congestive heart failure and systemic hypertension (respective rates for the 3 groups, 23.5%, 5.4%, and 9.1%, and 4.8%, 1.0% and 1.6%; P < 0.001 for both comparisons). Admitting physicians in the ED correctly identified ECG-LVH in 44 of 195 patients (sensitivity, 22% {95% CI, 17% to 28%}* and specificity, 98% {97.6% to 98.7%}*).

Conclusions

Patients with ECG-LVH were less likely to have acute cardiac ischemia and acute MI than were patients with primary ST-segment and T-wave or other ECG abnormalities but showed no difference in short-term mortality. Admitting physicians frequently did not correctly identify ECG-LVH.

Sources of funding: Agency for Health Care Policy and Research and National Library of Medicine Medical Information Program.

For article reprint: Dr. H.P. Selker, Division of Clinical Care Research, New England Medical Center, #63, 750 Washington Street, Boston, MA 02111. FAX 617-636-8023.

*Numbers calculated from data in article.


Commentary

Larsen and colleagues address the important issue of the interpretation of ECGs in patients presenting to the ED with symptoms of possible acute ischemic heart disease. In this setting, two factors must be considered: the need to identify patients with acute coronary occlusion who can benefit from acute reperfusion with a 25% to 30% reduction in the risk for early death and the substantial costs.

The authors establish the weakness of interpretation skills in ED situations. This finding has been observed before and probably was underestimated in this study because the physicians knew they were being observed. The study emphasizes the importance of this distinction because primary ST-segment changes were associated with a relatively high risk for MI and death. The lack of significant differences in mortality cannot be regarded as an important finding because the small number of patients with LVH who were evaluated prevented a robust statistical assessment of mortality differences.

The study leaves several key questions unanswered. What distinguishes patients (electrocardiographically and clinically) with and without acute ischemia among the patients with LVH? What causes the death of these patients with LVH if they do not have acute ischemia? Can a predictive instrument for MI and death be built for patients with LVH?

Robert M. Califf, MD
Duke University Medical Center Durham, North Carolina