Electrocardiographic reference ranges derived from 79,743 ambulatory subjects

Area of Science:

• Cardiology
• Medical Diagnostics
• Biostatistics

Background:

• Existing electrocardiogram (ECG) reference ranges are not representative of large populations and lack modern technological basis.
• Current norms for ECG intervals, heart rate, and QRS axis may not accurately reflect diverse age and sex demographics.

Purpose of the Study:

• To establish updated, age- and sex-specific reference ranges for ECG parameters using modern digital interpretation methods.
• To compare new reference ranges with existing norms and assess the impact of age and sex on ECG values.

Main Methods:

• Analysis of 79,743 baseline ECGs from clinical trials, interpreted digitally by cardiologists.
• Identification of a subgroup (n=46,129) with low cardiovascular disease probability for reference range determination.
• Calculation of reference ranges using 2nd and 98th percentiles for heart rate, PR, QRS, QRS axis, QT, and QTc intervals.

Main Results:

• Significant age- and sex-related variations were observed in all measured ECG parameters.
• New reference ranges were established: heart rate (48-98 bpm), PR interval (113-212 ms), QRS interval (69-109 ms), QRS axis (-40° to 91°), QT interval (325-452 ms), QTc-Bazett (361-457 ms), QTc-Fridericia (359-445 ms).
• Digital interpretation showed minimal differences compared to paper tracings and computer algorithms.

Conclusions:

• Modernized ECG reference ranges are significantly different from previously reported norms and general use values.
• Age and sex profoundly influence normal ECG values, necessitating updated reference standards.
• Large cohort studies are crucial for comprehensive assessment, and ECG reference ranges require modernization.