Improving the precision of QT measurements

Area of Science:

• Cardiology
• Clinical Pharmacology
• Regulatory Science

Background:

• Accurate QT interval measurement is crucial for regulatory submissions and drug development.
• Current manual or semi-automated methods have variability, requiring large sample sizes (50-70 subjects) in thorough QT/QTc studies.
• ICH E14 guidelines emphasize the importance of QT interval assessment.

Purpose of the Study:

• To compare the reproducibility and precision of semi-automated (SA) and high-precision QT (HPQT) methods for ECG extraction and QT interval measurement.
• To evaluate these methods in two thorough QT/QTc (TQT) studies.

Main Methods:

• Analysis of data from 35 healthy subjects in two crossover TQT studies (placebo and moxifloxacin).
• Both SA and HPQT methods measured RR and QT intervals on a single beat basis using the COMPAS software package's QT algorithm.
• ECGs were analyzed from lead II or the lead with the highest quality T-wave at protocol-specific timepoints.

Main Results:

• Moxifloxacin's effect on the QTc interval was highly reproducible with both methods, meeting assay sensitivity.
• Pairwise comparison of QTcF values showed high agreement between SA and HPQT methods, with no bias and small mean differences (<1.5 ms).
• HPQT improved QTc measurement precision by 31% in Study I and 15% in Study II compared to SA.

Conclusions:

• The HPQT technique accurately detected moxifloxacin's effect, similar to SA methods, but with significantly improved precision.
• Enhanced QTc measurement precision can reduce false positives and sample size in TQT studies.
• Improved QT assessment utility in early clinical development is a key implication.