Automated precordial mapping for S-T segment analysis: variability in serial mappings of normal subjects and patients...

An automated method of precordial mapping using a modified Caceres U.S. Public Health Service Electrocardiogram Diagnosing Program has been developed. The S-T segment elevation was measured in three successive complexes and averaged for each of the 35 precordial leads. The onset of the S-T segment (J point) was accurately located in over 99 percent of instances. The time required to sample the 35 leads averaged 8 1/2 minutes with subsequent data analysis requiring an additional 7 minutes. The S-T segment variability between serial mappings done over a 1 to 2 hour period was determined in normal subjects and patients with stable S-T elevation. The average S-T segment elevation/35 leads in normal subjects was 1.28 mv (range 0.41 to 2.14) and the between-mapping variability was +/- 0.25 mv at the 95 percent confidence level. The average S-T segment elevation/35 leads in the patients was 4.01 mv (range 1.35 to 7.28) mv. The between-mapping variability was +/- 0.29 mv (95 percent confidence level), and was not statistically different from the variability in normal subjects (P less than 0.05).