Table 2

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.