Improved Detection of Coronary Artery Disease by Novel Methods of Exercise ECG Analysis - A Multicenter Study


SUMMARY

Novel computerized method for comprehensive analysis of exercise electrocardiogram (ECG) to support the doctor's decision making in diagnosing coronary artery disease (CAD) has been developed in Tampere University of Technology. The new method designated ST/HR hysteresis observes both the exercise and recovery phases of the exercise test and proportionates the ST-segment depression (index of myocardial ischemia) to the heart rate (index of myocardial oxygen demand). According to the clinical validation performed in co-operation with Tampere University Hospital with 347 patients, the ST/HR hysteresis improved the diagnostic accuracy of the exercise ECG in detection of CAD nearly up to 90% from the present 75%. In addition, the method has been shown to be more reproducible and less sensitive to the ST-segment depression measurement point and used ECG-leads.

In the diagnosis of CAD the exercise test is in a key position, since based on its positive result the patient is referred for further examinations, e.g., myocardial isotope imaging or coronary angiography. Exercise test is noninvasive, inexpensive and almost riskless. At present, every fourth exercise ECG is interpreted falsely. As a consequence, many patients needing treatment are dropped out from further examination, and on the other hand staff loading and expensive further examinations are performed for healthy subjects.

The primary working hypothesis of the project is that the diagnostic accuracy of the exercise ECG analysis in the detection of the presence, severity and jeopardy of CAD can be improved significantly, up to about 90% from the present 75%, by the novel methods of ST- segment/heart rate analysis.

Before the ST/HR hysteresis can be widely taken into a clinical practise, the results achieved have to be validated in a multicenter approach. For this purpose the exercise ECGs of 481 patients have been digitally stored in Turku University Central Hospital (TUCH) and the exercise ECGs of 675 patients stored in Helsinki University Central Hospital (HUCH). The myocardial isotope imaging in TUCH material and coronary angiography in HUCH material has been performed for every patient. These images have been interpreted considerably more detailed than in normal clinical practice enabling the validation and further development of the method. It is an objective to expand the multicenter study also to other countries of Europe and research collaboration with Lund University has already been agreed.

In addition, the computer program enabling the clinical use of the ST/HR hysteresis will be developed further especially the user-interface need to be built to meet the requirements of hospital routine. In connection to the multicenter study the possibility to develop the method further to detect also the severity and jeopardy of CAD will be studied. The further development will not only be based on statistical analysis of the patient materials but also the human body volume conduction model developed in Tampere University of technology will be applied in simulation of myocardial ischemia.

The socio-economic impact of the proposed project will be considerable. For example, if the recently published 15% improvement in specificity and 18% improvement in sensitivity obtained by using ST/HR hysteresis can be verified in the proposed multicenter study, the annual amount of false positive diagnosis will be estimated to reduce by more than 400 000 patients resulting in total savings of more than 200 million ECUs per year in health care costs in Europe. What is even more important, the amount of patients with CAD who are misdiagnosed (false negatives) could be reduced by more than 40 000 patients annually, improving the quality of life and decreasing markedly the risk of sudden death of these patients.


1. BACKGROUND

1.1 SUMMARY OF THE ISSUES INVOLVED

1.2 CURRENT STATE OF KNOWLEDGE

1.3 SOCIO-ECONOMIC IMPACT

1.4 BENEFITS

1.5 LIST OF THE MOST RELEVANT PUBLICATIONS OF THE GROUP

2 OBJECTIVES AND METHODS

Table I. The objectives of the project
I To clinically evaluate the validity of the improved diagnostic accuracy of the ST/HR hysteresis in detection of the presence and severity of CAD and determine the diagnostic criteria to be used in clinical practice
II To work out a recommendation for harmonised clinical use of ST/HR hysteresis with respect to the diagnostic criteria, signal processing, ECG-leads, and ST-segment measurement point
III To provide basis for clinical implementation of ST/HR hysteresis in commercial exercise analysers accessible to clinical users
IV To establish a CD-ROM based European exercise ECG data library

2.2 METHODOLOGY TO BE APPLIED

2.2.1 Study population

2.2.2 Methods of ST/HR analysis

2.2.3 Exercise ECG test

2.2.4 Coronary angiography

2.2.5 Isotope SPECT myocardial imaging

2.2.6 Statistical methods

3. RESEARCHERS AND RESOURCES

4. EXPLOITATION PLANS

4.1 DELIVERABLES FOR EXPLOITATION

REFERENCES


Last updated 1998-03-10