Prolonged QT Interval Diagnosis Suppression by a Widely Used Computerized ECG Analysis System

Background- Clinicians commonly rely on automated diagnostic interpretations for initial, point-of-care identification of ECG abnormalities. Our study goal was to investigate how one widely used computerized ECG analysis system performs in labeling prolongation of heart rate-corrected QT interval (QTc), an arrhythmia risk marker. Methods and Results- ECGs acquired in 2009-2010 from patients >= 18 years old within the University of Michigan Health System, analyzed by the Marquette 12SL ECG Analysis Program (GE Healthcare), and exhibiting sinus rhythms with heart rate <100 beats per minute and QRS duration <120 ms constituted our database. Of 97 046 study ECGs (48.2% from males), a prolonged 12SL-calculated QTc value (ie, >= 470 ms in females >60 years old, and >= 460 ms in other sex/age groups) was displayed in 16 235 (16.7%). Nonetheless, for only 7709 (47.5%) of these ECGs with prolonged QTc did the automated interpretation include an accompanying "Prolonged QT" diagnostic statement. Such prolonged QT under-reporting was manifest across all patient environments and reflected algorithmic suppression of the diagnosis, attributable to ECG waveform-based criteria, in 8526 (52.5%) ECGs with prolonged QTc. Of the latter ECGs with prolonged QT diagnosis suppression, the computer declared 3588 (42.1%) "Normal" despite QTc prolongation. Conclusions- In evaluating an adult patient whose 12SL-interpreted ECG lacks a prolonged QT diagnostic statement (assuming sinus rhythm <100 beats per minute and QRS duration <120 ms), physicians should examine the actual QTc value displayed on the report before concluding that this parameter is normal. Assessment of the clinical impact of prolonged QT diagnosis suppression by ECG waveform-based criteria is warranted.