Table 4 Calculated positive and negative predictive values for arrhythmia from electrocardiography cutpoints based on incidence of arrhythmias in significant tricyclic antidepressant poisonings (seizures, coma or ingested dose > 1.5 g) in Newcastle (7%)
| Â | Positive predictive value (%) | Negative predictive value (%) | Likelihood ratio |
|---|---|---|---|
QRS ≥ 100 ms | 7.5 | 94.7 | 1.08 |
QRS > 120 ms | 19 | 94.4 | 3.11 |
QRS ≥ 160 ms | 32.8 | 93.7 | 6.5 |
QTc (Bazett's) > 500 | 10.0 | 96.2 | 1.48 |
R wave in aVR > 3 mm | 12.7 | 95.5 | 1.93 |
R/S ratio in aVR > 0.7 | 41.2 | 94.7 | 9.33 |