Stress Electrocardiography: A Comparison Of Conventional And Recent Criteria With Angiographic Correlation

Abstract

INTRODUCTION:

Stress electrocardiography has been the most commonly employed noninvasive method for the diagnosis of significant coronary artery disease. The most extensively studied variable of the exercise electrocardiogram is ST segment depression. It has been found to correlate variably with the presence of angiographic ally demonstrable coronary artery disease (CAD). This can been attributed to various factors for instance mild CAD, ventricular dysfunction, previous myocardial infarction (MI), sub-maximal stress1, asymptomatic population2 and a host of other factors.

METHODOLOGY:
1. Patient selection
Ninety-nine patients referred for evaluation of chest pain or assessment of effort tolerance were studied retrospectively. Patients were excluded on account of the following reasons:

2. Stress electrocardiography
Stress tests were performed on a multichannel computerized treadmill machine (Model: Quinton 2000). All patients performed graded maxim al exercise test in accordance with the Bruce Protocol the exercise end point was reached when 90% of the predicted maximal heart rate was reached or when one or more of the following criteria were present.

RESULTS:

Out of a total of 99 subjects(97 males), 27 were in the  age group 21-40 years and the rest above 40. T evidence of thirty seven had electrocardiographic evidence of transmural myocardial infarction (21 anterior), 14 inferior and 2 both ant and inf.)

DISCUSSION:

The primary purpose of this study was to delineate whether the new criteria offered a significant improvement in the sensitivity over the conventional criteria, without adversely affecting the specificity and predictive value. I t is apparent from Table- 2 that the recent criteria offer an improvement in sensitivity from 71% to 82% in the group as a whole and from 62% to 76% in those with previous MI. This improve-A well known variable, occurrence of chest pain on exercise, although relatively in-sensitive (37%) was found to be highly specific(97%) for ischemic heart disease.

CONCLUSION:

With the use of new criteria in our study, out of a total of 99 patients, 8 additional cases were diagnosed as positive when compared with conventional criteria An increase in sensitivity of 10-14% appears significant specially when the specificity and predictive value remain unaffected.The new criteria would not only be more beneficial in diagnosing patients who have less extensive coronary disease (single and double vessel disease) in whom the incidence of false negative tests is known to be relatively high, but also in correctly identifying false positive ST segment response.