title: Changing electrocardiographic recording technology and diagnostic accuracy of myocardial infarction criteria. Improved standards for evaluation of ECG measurement precision.
abstract: An analytical study was performed to estimate the magnitude of the visual Q wave duration bias produced by pressurized ink round stylus electrocardiographic (ECG) recorders. With a paper speed of 25 mm/sec and the ECG tracing width of 0.25 mm, the visually measured Q waves are on the average 8 msec too short. The corresponding error with the older type flat stylus recorder is less than 2 msec. Considerable differences can thus be anticipated in the frequency of observed ECG abnormalities in studies which use different types of electrocardiographs. The effect of the visual Q wave duration measurement bias on the diagnostic ECG classification was investigated in a group of 237 patients with old myocardial infarction and 299 subjects with no clinical evidence of infarction. An 8 msec measurement bias toward too short Q wave duration was observed to result in a potential loss of diagnostic accuracy of about 25% in some ECG coding categories. As a corrective procedure, it is recommended that the baseline width produced by a round recording stylus of uniform thickness irrespective of the vertical deflection velocity should be less.
mesh_terms: D003936:Diagnosis, Computer-Assisted; D003951:Diagnostic Errors; D004562:Electrocardiography / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D009203:Myocardial Infarction / Q000175:diagnosis*; D014796:Visual Perception