Table 3.
Accuracies and Predictive Values of Pooled Conventional versus A-ECG Criteria in the Test Set
Disease (N = 208) |
Healthy (N = 107) |
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---|---|---|---|---|---|---|---|---|
TP | FN | TN | FP | Sensitivity(CLs) | Specificity(CLs) | Accuracy(CLs) | ||
Conventional ECG status | ||||||||
Abnormal (optimized pooled criteria) | 163 | 45 | 91 | 16 | 78%(72-84%) | 85%(77-91%) | 81%(76-85%) | |
Best individual parameter status* | ||||||||
Abnormal QTVI in lead II (>-1.64 units) | 161 | 47 | 87 | 20 | 77%(71-83%) | 81%(73-88%) | 79%(74-83%) | |
Best 1° A-ECG scores status* "Full Disclosure" (5-min) A-ECG: |
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Abnormal 9-parameter score | 185 | 23 | 98 | 9 | 89%(84-93%)‡ | 92%(85-96%) | 90%(86-93%)† | |
Abnormal 7-parameter score | 194 | 16 | 101 | 6 | 92%(88-96%)‡ | 94%(88-98%)† | 93%(90-96%)† | |
"Snapshot" (10-sec) A-ECG: | ||||||||
Abnormal 7-parameter score | 192 | 16 | 92 | 15 | 92%(88-96%)‡ | 86%(78-92%) | 90%(86-93%)† | |
Disease +LVSD (N = 41) |
Disease no LVSD (N = 44) |
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TP | FN | TN | FP | PPV (CLs) | NPV (CLs) | +LR | -LR | |
Conventional ECG status | ||||||||
Abnormal (optimized pooled criteria) | 39 | 2 | 10 | 34 | 53%(41-65%) | 83%(51-98%) | 1.23 | 0.21 |
Best individual parameter status* | ||||||||
Abnormal Z integral (>12.4 mV*ms) | 28 | 13 | 31 | 13 | 68%(52-82%) | 70%(55-83%) | 2.31 | 0.45 |
Best 2° A-ECG scores status* | ||||||||
Abnormal 5-parameter score | 34 | 7 | 41 | 3 | 92%(78-98%)‡ | 85%(72-94%) | 12.16 | 0.18 |
A-ECG, advanced ECG; LVSD, left ventricular systolic dysfunction; TP and FP, true and false positives; TN and FN, true and false negatives; CLs, exact 95% binomial confidence limits; PPV and NPV, positive and negative predictive values; +LR and -LR, positive and negative likelihood ratios; QTVI, the QT interval variability index; Z integral, the total integral of the Z-lead QRS complex above 5 Hz.
*The best individual parameters and their cut-off values and the best A-ECG scores are all carried over from the training set and are not necessarily fully optimized with respect to the test set.
†P < 0.05 and ‡P < 0.0001 versus the optimized pooled conventional ECG criteria.