| Accardi AJ et al, 2002 USA | 45 patients with difficult narrow complex tachycardia (heart rate range: 150–250 beats/min) | Prospective comparative cohort | Correct ECG diagnosis | 63% 25 mm/s standard group v 71% 50 mm/s ECG; difference in means 8.6% (95% CI 2, 15%); p = 0.002 | Small numbers |
| 8 Emergency physicians reviewed the ECGs, blinded to clinical information. | Correct ECG diagnosis of atrial flutter | 40% 25 mm/s standard group v 52% 50 mm/s ECG; difference in means 12.5% (95% CI 1, 24%); p = 0.008 | Definitive diagnosis was potentially inaccurate |
| Definitive diagnosis depended upon agreement between the ‘official diagnosis’ in the case notes and a cardiologist who reviewed each case. | Correct diagnosis of atrial fibrillation | 85% 25 mm/s standard group v 90% 50 mm/s ECG difference in means 4.5% (95% CI −5, 14%); p = 0.046 | Review of 25 mm/sec ECGs was followed by review of 50 mm/sec ECGs two weeks later. The reviewers may have learned more about ECG diagnosis in that time, biasing the results. Intraobserver variability should have been assessed |
| Correct diagnosis of PSVT | 73% 25 mm/s standard group v 78% 50 mm/s ECG difference in means 5% (95% CI –6, 16%); p = 0.18 | |
| correct diagnosis of sinus tachycardia | 56% 25 mm/s standard group v 81% 50 mm/s ECG | |