ECG characteristics at baseline and at 5-year follow-up in patients with AS, stratified by sex
| Female (n=79) | Male (n=93) | |||||||
| Baseline | Follow-up | Change | P value | Baseline | Follow-up | Change | P value | |
| ECG measurements | ||||||||
| Heart rate, beats/min | 66 (59, 73) | 65 (60, 73) | 1 (−4, 7) | 0.351 | 64 (57, 73) | 65 (58, 73) | 1 (−6, 7) | 0.938 |
| PR interval*, ms | 160 (140, 170) | 158 (146, 172) | 4 (−4, 10) | 0.029 | 170 (160, 180) | 173 (156, 189) | 4 (−4, 12) | 0.013 |
| QRS interval†, ms | 80 (76, 90) | 82 (76, 90) | 1 (−4, 9) | 0.149 | 90 (80, 100) | 91 (86, 100) | 3 (−4, 8) | 0.004 |
| QTcB‡, ms | 410 (393, 426) | 411 (398, 422) | 4 (−9, 15) | 0.173 | 399 (386, 417) | 404 (388, 422) | 5 (−10, 22) | 0.056 |
| Heart rhythm, n (%) | ||||||||
| Sinus | 77 (97.5) | 78 (98.7) | n.a. | n.a. | 90 (96.8) | 89 (95.7) | n.a. | n.a. |
| Bradycardia | 3 (3.8) | 4 (5.1) | 6 (6.5) | 5 (5.4) | ||||
| Tachycardia | 0 (0.0) | 0 (0.0) | 2 (2.2) | 2 (2.2) | ||||
| Atrial fibrillation | 0 (0.0) | 0 (0.0) | 2 (2.2) | 2 (2.2) | ||||
| Pacemaker rhythm | 0 (0.0) | 1 (1.3) | 1 (1.1) | 2 (2.2) | ||||
| Other | 2 (2.5) | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||||
Data are expressed as median (Q1, Q3) or number (%) and presented for 172 patients if not stated otherwise. Comparison between ECG measurements at baseline and follow-up is calculated by related-samples Wilcoxon signed-rank test.
*n=169 at start, n=167 at follow-up.
†n=171 at start, n=170 at follow-up.
‡QTcB is the heart rate-corrected QT interval according to Bazett; n=171 at start, n=168 at follow-up.
AS, ankylosing spondylitis; n.a., not applicable; Q1, 25th percentile; Q3, 75th percentile.