onventional non-invasive tests, such as standard exercise treadmill test, dobutamine stress echocardiography, and stress radionuclide myocardial perfusion imaging, are frequently used as diagnostic tools for coronary artery disease (CAD), but all these methods have some demerits. For example, the standard exercise treadmill test is not applicable for patients with orthopedic problems, and dobutamine stress echocardiography may induce ventricular and supraventricular arrhythmias. The cost of stress radionuclide myocardial perfusion imaging is high. 1,2 Therefore, non-invasive modalities with high sensitivity and specificity at low cost are desirable. Previous studies in experimental animals have shown that acute myocardial ischemia results in a decreased conduction velocity of the myocardium, which manifests as QRS prolongation on the surface electrocardiograph (ECG). [3][4][5][6][7] Prolonged QRS duration on the standard 12-lead ECG during exercise has been demonstrated in CAD patients, [8][9][10][11][12] but it is difficult to detect subtle changes in the prolongation of the QRS interval on the standard 12-lead ECG. However, these can be evaluated by using the filtered QRS wave duration (fQRSd) on the signal-averaged ECG (SAECG). [13][14][15][16][17] In our previous study, 18 using a portable SAECG recording device, we performed bedside recording of SAECG before and after dipyridamole stress and measured subtle changes in QRS prolongation. QRS prolongation by more than 5 ms suggested the presence of CAD with high sensitivity and specificity. However, that study was retrospective, so in the present study we prospectively investigated whether CAD could be diagnosed by the same method.
Methods
Study PatientsThe study population consisted of patients who had chest pain as the chief complaint and who were hospitalized in the Third Department of Internal Medicine of Kurume University. Medical history was carefully obtained and physical examination was done. Standard 12-lead ECG, chest X-ray, and 2-dimensional (D) echocardiography were performed. Patients were excluded if they had one of the following: unstable angina pectoris, bundle branch block (QRS duration >120 ms), left or right ventricular hypertrophy, Wolff-Parkinson-White syndrome, previous myocardial infarction, valvular heart disease, congenital heart disease, bronchial asthma or abnormal electrolytes, or if they were taking anti-arrhythmic drugs. Patients who did not give consent were also excluded. As a result, 73 patients (44 males, 29 females; mean age 63±10 years) were enrolled after giving written informed consent. The study protocol was approved by the institutional ethical committee of human investigations. Background In a retrospective study portable-type signal-averaged electrocardiography (SAECG) with dipyridamole stress was found to identify patients with coronary artery disease (CAD) at their bedside with high sensitivity and specificity, so the utility of this method was prospectively investigated in the present study.
Methods and ResultsStand...