Prolonged QT interval diagnosis suppression by a widely used computerized ECG analysis system

Area of Science:

• Cardiology
• Medical Informatics
• Electrocardiography

Background:

• Automated ECG interpretations are crucial for point-of-care abnormality detection.
• The heart rate-corrected QT interval (QTc) prolongation is a significant marker for arrhythmia risk.

Purpose of the Study:

• To evaluate the performance of a widely used computerized ECG analysis system (Marquette 12SL) in identifying prolonged QTc intervals.

Main Methods:

• Analysis of 97,046 ECGs from adult patients at the University of Michigan Health System (2009-2010).
• Inclusion criteria: sinus rhythm, heart rate <100 bpm, QRS duration <120 ms.
• Evaluation of Marquette 12SL's labeling of prolonged QTc (≥470 ms in females >60, ≥460 ms in others).

Main Results:

• 16.7% (16,235/97,046) of ECGs showed a prolonged QTc.
• Only 47.5% (7,709/16,235) of these ECGs with prolonged QTc received an automated "Prolonged QT" diagnosis.
• Algorithmic suppression due to waveform criteria led to under-reporting in 52.5% (8,526/16,235) of cases, with 42.1% (3,588/8,526) incorrectly labeled "Normal".

Conclusions:

• Physicians should manually review QTc values on ECG reports, even when the automated interpretation is normal, especially for patients with sinus rhythm <100 bpm and QRS duration <120 ms.
• Further research is needed to assess the clinical impact of diagnostic suppression of prolonged QT by ECG waveform criteria.