Table 2 Variable definitions for statistical analysis
Variable | Definition | Type of Variable |
|---|---|---|
ΔQTC | ≥ +25 ms increase in QTC interval from previous day lasting 3 consecutive days [10] | Continuous (expected range, 10-100 ms) |
Acute allograft rejection | EMB category 1R or 2R or 3R with confirmation by treating physician | Categorical; dichotomous (yes/no) No = 0; Yes = 1R or 2R or 3R |
Days to rejection | Number of days from first positive ECG criterion to mild, moderate, or severe rejection diagnosis. If the ECG criterion follows rejection, a negative # of days will be reported. | Continuous (expected range -365 to +365) |
Acute rejection severity | EMB category: 1R (mild), 2R (moderate), 3R (severe) | Categorical |
Cardiac rhythm | Sinus rhythm, atrial fibrillation, atrial flutter, junctional rhythm | Categorical |
Heart rate | Heart rate per minute calculated from 30 s rhythm strip | Continuous (expected range, 60-120) |
P wave duration | Interval from beginning to end of P wave in ms (measure of intra-atrial conduction delay) | Continuous (expected range, 70-126 ms) |
QRS duration | Interval from beginning to end of the QRS waveform | Continuous (expected range, 72-160 ms) |
PR interval | Interval from the beginning of the P wave to the beginning of the QRS complex measured in ms. PR interval > 200 ms indicates an abnormal delay of conduction (1st degree AV block). | Continuous (expected range, 112-240 ms) |
QRS amplitude | Height of QRS waveform in μV | Continuous (expected range, 500-1000 μV |
TPEAK - TEND | Interval from the peak of the T wave (or nadir in inverted T waves) to the end of the T wave in ms. Prolonged TPEAK -TEND indicates heterogeneity of repolarization and risk for arrhythmia | Continuous (expected range, 112-240 ms) |