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Exercise electrocardiography for diagnosis of coronary artery disease: impact of sampling rate on the diagnostic performance of ST/HR-loop based on data from early recovery phase
KTH, School of Technology and Health (STH), Medical Engineering.
KTH, School of Technology and Health (STH), Medical Engineering.
KTH, School of Technology and Health (STH), Medical Engineering.
2007 (English)In: Clinical Physiology and Functionel Imaging, ISSN 1475-0961, Vol. 28, no 2, 96-100 p.Article in journal (Refereed) Published
Abstract [en]

Quantitative analysis of electrocardiographic ST-segment/heart rate relationship (ST/HR loop) during early recovery phase of exercise stress test provides a sensitive tool for the detection of coronary artery disease (CAD). This study evaluates the effect of data sampling frequency on the diagnostic performance of ST/HR loop in 1876 patients undergoing a routine exercise test on a bicycle ergometer. CAD was verified angiographically in 668 patients and excluded by coronary angiography (n = 119), myocardial scintigraphy (n = 250) and on clinical grounds (n = 839) in 1208 patients. The normalized ST/HR loop area was calculated in all cases by integration of ST-segment amplitude difference from the end of exercise to the end of the first 3 min of recovery period over HR and dividing the integral by the HR difference over the integration period. The effect of different sampling rates (one, two and five samples per minute) on the CAD discrimination ability of ST/HR loop area was subsequently evaluated using receiver operating characteristic (ROC) curves. Reduction in ST/HR data sampling frequency from two to one sample per minute resulted in a significantly decreased diagnostic performance of the ST/HR loop whereas no differences in CAD discrimination capacity were observed between sampling frequencies of two and five samples per minute. The choice of ST/HR data sampling frequency may have a significant impact on the CAD diagnostic ability of the ST/HR loop. The use of sampling frequency below two samples per minute results in a significantly diminished diagnostic performance, a fact that should be taken into consideration when employing ST/HR diagnostic procedures.

Place, publisher, year, edition, pages
2007. Vol. 28, no 2, 96-100 p.
Keyword [en]
exercise stress test; ischaemic heart disease; rate recovery loop; sampling frequency; ST-segment depression
National Category
Medical Laboratory and Measurements Technologies
Identifiers
URN: urn:nbn:se:kth:diva-11332DOI: 10.1111/j.1475-097X.2007.00780.xISI: 000252897100005Scopus ID: 2-s2.0-39149098147OAI: oai:DiVA.org:kth-11332DiVA: diva2:274144
Note
QC 20100726Available from: 2009-10-27 Created: 2009-10-27 Last updated: 2010-12-06Bibliographically approved
In thesis
1. Diagnostic and Prognostic Value of Exercise Electrocardiographic Test Variables in Coronary Artery Disease
Open this publication in new window or tab >>Diagnostic and Prognostic Value of Exercise Electrocardiographic Test Variables in Coronary Artery Disease
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The diagnostic performance of conventional analysis of the exercise electrocardiographic (ECG) test for the detection of coronary artery disease (CAD) is limited to 70-75%. The exercise ECG test is the most widely used non-invasive method for assessing CAD and even a small improvement in the diagnostic performance is important. The objective of this thesis was to investigate the diagnostic performance of the exercise ECG test for diagnosis of CAD and the prognostic performance of the test for predicting acute myocardial infarction (AMI), in both men and women.

In the diagnostic part of the present study, aimed at finding the optimal diagnostic information during the exercise and recovery phase, 1,877 electrocardiograms selected from 8,322 consecutive patients undergoing a routine exercise test on bicycle ergometer were evaluated. CAD was verified angiographically in 669 patients and excluded in 1,208 patients, by angiography (119 patients), by myocardial scintigraphy (250 patients), or on clinical grounds (839 patients).

The diagnostic performance of ST-segment amplitude, and the difference between heart rate (HR) matched recovery and exercise ST-segment amplitudes (ST/HR difference), were evaluated by constructing receiver operating characteristic (ROC) curves for each sample point every 12th second during 10 minutes of recovery as well as the last 4 minutes of exercise for the ST-segment amplitude. ST-segment amplitude performed better after exercise than during exercise and best within the first 2 minutes of recovery. Its diagnostic ability did not differ from the ST/HR difference. Both methods performed better in men than in women and the diagnostic information appeared mainly in leads I, -aVR, II, V4, V5 and V6.

The effect of different sampling rates (1, 2 and 5 samples/min) on the CAD discrimination ability of ST/HR loop area was evaluated by using ROC curves. A use of sampling frequency below 2 samples/min resulted in a significantly diminished diagnostic performance.

ST-segment and ST/HR variables were compared during exercise and during early post-exercise recovery in terms of diagnostic discrimination capacity and optimal partition values. Discriminating capacity of the methods was evaluated by the use of ROC areas. Partition values, providing the combination of the best sensitivity and specificity, were established. The results demonstrate that analysis of post-exercise ST/HR hysteresis offers the most accurate and gender indifferent identification of patients with CAD.

The prognostic part of the study included 8,317 of the 8,322 patients and covered a mean follow-up period of 9.5 years. This part of the study was used to evaluate the long-term prognostic value of ST/HR hysteresis in predicting AMI and all-cause mortality in men and women. ST/HR hysteresis appears to improve the prognostic ability of an exercise ECG test for AMI and all-cause mortality in a long term perspective compared to conventional ST-segment and ST/HR indicators in both genders and clearly more markedly in women.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 65 p.
Series
Trita-STH : report, ISSN 1653-3836 ; 2009:3
Keyword
exercise ECG test, coronary artery disease, acute myocardial infarction
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:kth:diva-11289 (URN)978-91-7415-457-3 (ISBN)
Public defence
2009-11-06, Sal 4-221, Alfred Nobels Allé 12, Huddinge, 09:00 (English)
Opponent
Supervisors
Note
QC 20100726Available from: 2009-10-14 Created: 2009-10-14 Last updated: 2010-07-26Bibliographically approved

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