Background and ObjectivesPoor R-wave progression (PRWP) is a common electrocardiographic diagnosis. However, the diagnostic usefulness of PRWP for coronary artery disease (CAD) and the plausible explanation for subjects with normal heart function are unclear.Subjects and MethodsWe included 20,739 subjects who had routine medical examinations and applied the commonly used criteria (R-waves in V3 or V4 ≤2 mm) and the Marquette criteria in the current study. Subjects with PRWP by the Marquette criteria, but with no evidence of specific causes, were identified. Healthy age- and gender-matched controls were selected randomly for comparing cardiothoracic ratios.ResultsThe commonly used criteria in practice were met by 372 of the 20,739 subjects (1.8%). The Marquette criteria were met by 96 subjects (0.5%), and 82 of who agreed to medical evaluation. Five subjects had known CAD and only one subject was shown to have a silent myocardial infarction by additional testing. Therefore, the positive predictive value of PRWP for CAD was 7.3% (6/82) based on the Marquette criteria. As compared with the control group, the subjects with PRWP had a significantly low cardiothoracic ratio (0.425 vs. 0.445, p<0.05), especially among the male group (0.454 vs. 0.407, p=0.02).ConclusionThe positive predictive value of PRWP for CAD in the general population is so low that additional tests for diagnosis may be unreasonable. In addition, a low cardiothoracic ratio could be a plausible explanation of PRWP in subjects without any identifiable cause.