Table 2:
Electrocardiographic parameter summary
| Variable | Case Block 1 (n = 91) | Control Block 1 (n = 1783) | p-value c | Case block 1 (n = 85 d) | Case block 2 (n = 85 d) | p-value e |
|---|---|---|---|---|---|---|
| Arrhythmias, n(%) | ||||||
| AF, any in block n | 31 (34%) | 373 (20%) | 0.0029 | 30 (35%) | 17 (24%) | 0.0258 |
| AF, present block n not block n-1 | 13 (14%) | 64 (3%) | <0.0001 | 13 (15%) | 3 (4%) | 0.0086§ |
| 2° HB, any in block n | 36 (40%) | 332 (18%) | <0.0001 | 33 (39%) | 7 (10%) | <0.0001f |
| 2° HB, present block n not block n-1 | 26 (29%) | 162 (3%) | <0.0001 | 26 (31%) | 3 (4%) | <0.0001f |
| Pauses, any in block n | 30 (33%) | 376 (20%) | 0.0073 | 30 (35%) | 8 (12%) | <0.0001f |
| Pauses, present block n not block n-1 | 22 (24%) | 229 (12%) | 0.0020 | 22 (26%) | 5 (7%) | 0.0004§ |
| Trend Slope (Δyn/Δxn)b, median (IQR) | ||||||
| QRS Amplitude Averaged + (μV/hr) | 321 (119 – 641) | 312 (138 – 627) | NS | 305 (119 – 623) | 223 (118 – 447) | NS |
| QRS Amplitude Averaged + (μV/hr) | 310 (125 – 613) | 285 (137 – 608) | NS | 243 (122 – 608) | 210 (97 – 499) | NS |
| PR Interval + (ms/hr)a | 8.0 (4.5 – 14.1) | 6.7 (3.6 – 12.6) | NS | 5.9 (3.7 – 9.3) | 8.0 (3.9 – 16.2) | NS |
| PR Interval − (ms/hr)a | 9.5 (4.3 – 20.0) | 6.7 (3.7 – 13.4) | 0.0466 | 6.5 (3.5 – 20.5) | 7.6 (3.6 – 13.0) | NS |
| QRS Duration + (ms/hr) | 6.5 (2.8 – 13.6) | 4.2 (1.8 – 8.6) | 0.0020 | 8.1 (3.3 – 14.1) | 3.6 (1.9 – 7.8) | 0.0488 |
| QRS Duration − (ms/hr) | 5.5 (3.0 – 13.2) | 3.7 (1.6 – 8.1) | 0.0011 | 5.3 (3.0 – 13.3) | 4.2 (1.9 – 8.1) | 0.0019f |
| QTc + (ms/hr) | 16.9 (8.3 – 37.3) | 13.9 (7.6 – 27.5) | NS | 16.7 (8.8 – 32.2) | 13.5 (7.4 – 25.6) | NS |
| QTc − (ms/hr) | 16.4 (9.5 – 53.3) | 13.3 (6.9 – 25.5) | 0.0086 | 15.6 (8.8 – 54.4) | 12.7 (7.2 – 36.5) | NS |
| RR + (ms/hr) | 48.8 (26.5 – 76.1) | 52.8 (27.2 – 98.2) | NS | 40.8 (26.4 – 75.9) | 40.6 (19.0 – 69.5) | NS |
| RR − (ms/hr) | 45.1 (23.2 – 96.4) | 53.8 (25.6 – 112.9) | NS | 42.0 (18.5 – 90.4) | 32.9 (15.9 – 65.6) | NS |
| ST Lead II + (μV/hr) | 28.6 (13.1 – 67.1) | 15.0 (7.8 – 29.0) | <0.0001 | 29.1 (12.9 – 66.4) | 20.1 (8.6 – 37.9) | 0.0020f |
| ST Lead II − (μV/hr) | 28.5 (14.0 – 48) | 15.0 (8.0 – 30.4) | <0.0001 | 27.0 (14.0 – 47) | 20.5 (8.3 – 35.5) | NS |
| ST Lead V2 + (μV/hr) | 16.0 (6.2 – 33.5) | 10.5 (5.5 – 19.5) | 0.0009 | 16.5 (5.4 – 34.6) | 12.6 (6.5 – 26.2) | NS |
| ST Lead V2 − (μV/hr) | 15.8 (6.5 – 33.0) | 10.5 (5.3 – 20.7) | 0.0060 | 16.3 (6.6 – 33.0) | 11.7 (6.4 – 22.8) | NS |
| Trend Slope Comparison (Δyn/Δxn – Δyn-1/Δxn-1) b, median (IQR) | ||||||
| QRS Amplitude Averaged + (μV/hr) | 43 (−148 – 278) | 10 (−212 – 243) | NS | 69 (−131 – 277) | 13 (−155 – 157) | NS |
| QRS Amplitude Averaged − (μV/hr) | 45 (−108 – 238) | −4 (−187 – 203) | NS | 43 (−171 – 301) | 23 (−162 – 159) | NS |
| PR Interval + (ms/hr)a | 0.0 (−2.7 – 2.8) | 0.2 (−4.8 – 5.1) | NS | 0.1 (−3.3 – 3.3) | −0.7 (−3.7 – 3.1) | NS |
| PR Interval − (ms/hr)a | 1.2 (−2.6 – 7.7) | 0.2 (−4.8 – 5.0) | 0.0210 | 0.3 (−4.2 – 7.9) | −0.15 (−4.0 – 5.2) | NS |
| QRS Duration + (ms/hr) | 0.4 (−2.6 – 7.1) | 0 (−3.7 – 3.9) | NS | 1.1 (−2.3 – 9.6) | −0.1 (−2.8 – 2.2) | NS |
| QRS Duration − (ms/hr) | 1.3 (−2.2 – 5.2) | 0.1 (−3.5 – 3.7) | 0.0072 | 2.2 (−1.1 – 6.1) | 0.4 (−2.7 – 2.7) | 0.0096f |
| QTc + (ms/hr) | 1.0 (−7.6 – 18.0) | 0.3 (−11.0 – 11.3) | NS | 1.0 (−7.7 – 18.3) | 0.1 (−8.9 – 11.4) | NS |
| QTc − (ms/hr) | −2.4 (−7.1 – 21.8) | 0.4 (−8.9 – 10.7) | NS | 0.1 (−7.7 – 23.8) | 0.2 (−9.9 – 19.8) | NS |
| RR + (ms/hr) | 3.9 (−23.4 – 29.3) | 3.3 (−31.8 – 38.3) | NS | 2.8 (−24.8 – 25.1) | 0.6 (−17.5 – 22.1) | NS |
| RR − (ms/hr) | 3.7 (−16.2 – 37.4) | 0.1 (−42.2 – 38.1) | NS | 3.3 (−15.2 – 37.7) | 0.2 (−16.2 – 17.4) | NS |
| ST Lead II + (μV/hr) | 6.3 (−5.4 – 32.3) | −0.4 (−11.5 – 11.1) | 0.0002 | 6.3 (−5.4 – 32.3) | −1.9 (−9.5 – 18.3) | 0.0201 |
| ST Lead II − (μV/hr) | 4.2 (−6.8 – 26.1) | −0.2 (−11.7 – 11.1) | 0.0029 | 4.5 (−8.7 – 26.1) | 2.0 (−10.7 – 12.8) | NS |
| ST Lead V2 + (μV/hr) | 2.4 (−8.7 – 10.6) | −0.1 (−7.9 – 7.7) | NS | 2.6 (−8.7 – 13.3) | 0.8 (−6.5 – 12.7) | NS |
| ST Lead V2 − (μV/hr) | 1.5 (−6.8 – 12.8) | 0.0 (−8.2 – 7.0) | NS | 1.5 (−6.8 – 12.8) | 2.3 (−5.2 – 11.1) | NS |
| Trend Change (Δyn) b, median (IQR) | ||||||
| QRS Amplitude Averaged + (μV) | 113 (54 – 181) | 86 (47 – 158) | NS | 102 (54 – 181) | 72 (41 – 141) | 0.0224 |
| QRS Amplitude Averaged − (μV) | 109 (65 – 165) | 85 (48 – 143) | 0.0462 | 98 (48 – 190) | 75 (31 – 126) | 0.0494 |
| PR Interval + (ms) a | 10 (5 – 15.5) | 7 (4 – 14) | 0.0347 | 8 (5 – 14) | 9 (5 – 15) | NS |
| PR Interval − (ms) a | 12 (5 – 17) | 7 (4 – 14) | 0.0270 | 8 (4 – 18) | 9 (4 – 12.5) | NS |
| QRS Duration + (ms) | 9 (4 – 16) | 4 (2 – 8) | <0.0001 | 11 (4 – 16) | 5 (2 – 12) | 0.0005f |
| QRS Duration − (ms) | 7.5 (3 – 13) | 5 (2.8 – 8) | 0.0015 | 8 (3 – 13) | 5 (2 – 8) | 0.0101f |
| QTc + (ms) | 24.4 (14.6 – 43.3) | 14.6 (8.5 – 26.7) | <0.0001 | 24.1 (11.9 – 44.6) | 16.8 (8.4 – 31.3) | 0.0035f |
| QTc − (ms) | 30.1 (11.1 – 56.9) | 14.4 (9.0 – 26.0) | <0.0001 | 30.1 (10.5 – 60.6) | 16.9 (8.4 – 34.4) | 0.0108f |
| RR + (ms) | 59 (35.5 – 134) | 61 (32 – 103) | NS | 62 (36 – 137) | 41 (18 – 70) | 0.0024f |
| RR − (ms) | 61 (28 – 120) | 58 (31 – 105) | NS | 51 (21 – 120) | 37 (22 – 71) | NS |
| ST Lead II + (μV) | 32 (15 – 70) | 16 (9 – 29.8) | <0.0001 | 34 (15 – 75) | 19 (9 – 41) | 0.0020f |
| ST Lead II − (μV) | 30 (14 – 66.5) | 16 (9 – 29) | <0.0001 | 30 (14 – 64.5) | 20 (12 – 45) | 0.0037f |
| ST Lead V2 + (μV) | 16 (8-33) | 11 (6 – 20) | 0.0003 | 18 (8 – 37) | 12 (6 – 20) | 0.0311 |
| ST Lead V2 − (μV) | 20 (9 – 41) | 11 (6 – 20) | <0.0001 | 20 (9 – 41) | 12 (6 – 22) | 0.0002f |
| Trend Change Comparison (Δyn-(n-1))b, median (IQR) | ||||||
| QRS Amplitude Averaged + (μV) | 21 (−29 – 77) | 0 (−59 – 61) | 0.0306 | 28 (−24 – 93) | −3 (−42 – 55) | NS |
| QRS Amplitude Averaged − (μV) | 10 (−22 – 104) | 0 (−42 – 49) | 0.0239 | 8 (−34 – 114) | 10 (−46 – 38) | NS |
| PR Interval + (ms)a | 0 (−3 – 3) | 0 (−5 – 4) | NS | −1 (−5.5 – 3.5) | 0 (−5 – 4) | NS |
| PR Interval − (ms)a | 1 (−1.5 – 4.5) | 0 (−4 – 4) | NS | 2 (−3.5 – 9.5) | 0 (−3 – 3) | NS |
| QRS Duration + (ms) | 1 (−1 – 6) | 0 (−3 – 3) | 0.0004 | 2 (−2 – 11) | 0 (−4 – 3) | NS |
| QRS Duration – (ms) | 1 (−1 – 5.75) | 0 (−3 – 3) | 0.0069 | 2 (−1 – 8) | −1 (−4.5 – 3) | 0.0211 |
| QTc + (ms) | 6 (−6 – 22) | 0.7 (−8.3 – 9.3) | 0.0365 | 6 (−6 – 24) | 0.8 (−9.4 – 12.9) | NS |
| QTc − (ms) | 7 (−5 – 25) | −0.20 (−8.5 – 8.2) | 0.0002 | 7 (−6 – 36) | −1.0 (−5.9 – 12.2) | NS |
| RR + (ms) | 21 (−19.5 – 55) | 1 (−33 – 37) | 0.0010 | 23 (−18 – 57) | −8 (−25 – 23) | 0.0019f |
| RR − (ms) | 12 (−16 – 54) | 2 (−31 – 35.5) | 0.0220 | 9 (−21 – 60.5) | −4 (−24 – 15) | 0.0451 |
| ST Lead II + (μV) | 7 (−7 – 35.5) | 0 (−10 – 10) | 0.0006 | 9 (−7.5 – 42) | 0 (−9 – 13) | NS |
| ST Lead II − (μV) | 9 (−6 – 30.5) | 0 (−10 – 10) | <0.0001 | 9 (−7 – 26) | 4 (−6 – 12) | NS |
| ST Lead V2 + (μV) | 2 (−4.5 – 10.5) | 0 (−7 – 6) | 0.0419 | 4 (−4 – 18.3) | 0 (−8 – 7) | NS |
| ST Lead V2 − (μV) | 6 (−2 – 25.5) | 0 (−6 – 7) | <0.0001 | 7.5 (−2 – 26) | 0(−6 – 10) | 0.0113f |
Abbreviations: AF – atrial fibrillation, HB – heart block, IQR – interquartile range
a
Reported where measureable given this is not measureable in atrial fibrillation
b
For each row, + denotes the measure for the dominant positive trend, and − denotes the measure for the dominant negative trend for that ECG parameter. All negative trend change and slope measurements are reported as the absolute value.
c
All univariate comparisons with p-value < 0.05 were also significant at q-value < 0.05, which corrects for false discovery rate due to multiple hypothesis testing
d
This reflects the number of patients who had a block 3 available, as this was required to calculate trend slope and trend change comparison values
e
All trend comparisons were performed using paired comparison with the Wilcoxon signed-rank test
f
These values were significant at the q-value < 0.05 level, which corrects for the false discovery rate due to multiple hypothesis testing