Table 1.
Characteristics of the study populations by postoperative QTc duration
| Characteristics | Stage I cohort (n = 497) |
Stage II cohort (n = 957) |
||||||
|---|---|---|---|---|---|---|---|---|
| QTc ≤ 440 msec (n = 346) |
QTc > 440 msec (n = 151) |
OR (95% CI) | P value | QTc ≤ 440 msec (n = 702) |
QTc ≤ 440 msec (n = 255) |
OR (95% CI) | P value | |
| Demographic | ||||||||
| Age (yr), mean (SD) | 64.0 (11.3) | 66.1 (11.3) | 1.03 (1.01 to 1.04)a | 0.007 | 62.5 (11.0) | 65.2 (11.2) | 1.02 (1.01 to 1.04) | 0.001 |
| Female sex, n (%) | 90 (26.0) | 56 (37.1) | 1.67 (1.12 to 2.52) | 0.013 | 182 (25.9) | 104 (40.8) | 1.97 (1.46 to 2.66) | <0.0001 |
| Self-reported ethnicity, n (%) | 0.74 | 0.63 | ||||||
| White | 275 (79.5) | 124 (82.1) | 1.0 | 586 (83.5) | 211 (82.7) | 1.0 | ||
| Black | 61 (17.6) | 24 (15.9) | 0.87 (0.52 to 1.46) | 90 (12.8) | 37 (14.5) | 1.14 (0.76 to 1.73) | ||
| Other | 10 (2.9) | 3 (2.0) | 0.67 (0.18 to 2.46) | 26 (3.7) | 7 (2.7) | 0.75 (0.32 to 1.75) | ||
| Medical history, n (%) | ||||||||
| Chronic obstructive pulmonary disease | 44 (12.7) | 18 (11.9) | 0.93 (0.52 to 1.67) | 0.8 | 78 (11.1) | 34 (13.3) | 1.23 (0.80 to 1.89) | 0.35 |
| Chronic renal dysfunction | 25 (7.2) | 19 (12.6) | 1.85 (0.98 to 3.47) | 0.06 | 35 (5.0) | 24 (9.4) | 1.98 (1.15 to 3.40) | 0.01 |
| Diabetes mellitus | 114 (32.9) | 49 (32.5) | 0.98 (0.65 to 1.47) | 0.91 | 255 (32.1) | 84 (32.9) | 1.04 (0.77 to 1.41) | 0.8 |
| Extracardiac arteriopathy | 64 (18.5) | 25 (16.6) | 0.87 (0.53 to 1.45) | 0.6 | 119 (17.0) | 43 (16.9) | 0.99 (0.6 to −1.46) | 0.97 |
| Preoperative LVEF (%), mean (SD) | 51.4 (16.2) | 45.9 (16.5) | 0.98 (0.97 to 0.99)b | 0.0007 | 53.0 (14.0) | 48.5 (15.1) | 0.98 (0.97 to 0.99) | <0.0001 |
| Preoperative QTc > 440 msec | 22 (6.4) | 60 (39.7) | 9.71 (5.65 to 16.68) | <0.0001 | 30 (4.3) | 91 (35.7) | 12.43 (7.95 to 19.43) | <0.0001 |
| Medication use at hospital admission, n (%) | ||||||||
| Angiotensin-converting enzyme inhibitors | 168 (48.6) | 69 (45.7) | 0.89 (0.61 to 1.31) | 0.63 | 282 (40.2) | 116 (45.5) | 1.24 (0.93 to 1.66) | 0.15 |
| Acetylsalicylic Acid | 239 (69.1) | 101 (66.9) | 0.90 (0.60 to 1.36) | 0.63 | 512 (72.9) | 183 (71.8) | 0.94 (0.69 to 1.30) | 0.72 |
| Beta-blockers | 194 (56.1) | 90 (59.6) | 1.15 (0.78 to 1.70) | 0.46 | 428 (61.0) | 159 (62.4) | 1.06 (0.80 to 1.42) | 0.7 |
| Calcium channel blockers | 55 (15.9) | 24 (15.9) | 1.00 (0.59 to 1.69) | 1.0 | 113 (16.1) | 41 (16.1) | 0.99 (0.68 to 1.48) | 1.0 |
| Diuretics | 77 (22.3) | 48 (31.8) | 1.63 (1.06 to 2.49) | 0.02 | 143 (20.4) | 81 (31.8) | 1.82 (1.32 to 2.51) | 0.0003 |
| Nitrates | 105 (30.3) | 51 (33.8) | 1.17 (0.78 to 1.76) | 0.45 | 231 (32.9) | 90 (35.3) | 1.11 (0.82 to 1.50) | 0.49 |
| Statins | 154 (44.5) | 61 (40.4) | 0.85 (0.57 to 1.25) | 0.4 | 303 (43.2) | 103 (40.4) | 0.90 (0.67 to 1.19) | 0.44 |
| Procedural factors, n (%) | ||||||||
| Aortic cross-clamp time (min), mean (SD) | 69.9 (40.0) | 84.3 (44.7) | 1.008 (1.004 to l.0l)c | 0.001 | 66.0 (34.3) | 80.5 (45.4) | 1.01 (1.0 to 1.01) | <0.0001 |
| Procedure type | 0.004 | <0.0001 | ||||||
| Off-pump CABG | 4 (1.2) | 1 (0.7) | 0.38 (0.04 to 3.84) | 14 (2.0) | 6 (2.4) | 0.53 (0.18 to 1.58) | ||
| On-pump CABG | 296 (85.5) | 110 (72.8) | 0.57 (0.28 to 1.19) | 626 (89.2) | 190 (74.5) | 0.38 (0.22 to 0.65) | ||
| CABG and valve | 26 (7.5) | 27 (17.9) | 1.60 (0.66 to 3.86) | 31 (4.4) | 34 (13.3) | 1.36 (0.66 to 2.79) | ||
| Valve | 20 (5.8) | 13 (8.6) | 1.0 | 31 (4.4) | 25 (9.8) | 1.0 | ||
| Genotype, n (%) | ||||||||
| IL1B rs 16994 | 1.29 (0.98 to 1.7) | 0.07 | 1.33 (1.06 to 1.67) | 0.01 | ||||
| CC | 144 (42.5) | 49 (32.7) | 263 (39.0) | 77 (30.8) | ||||
| CT | 146 (43.1) | 75 (50.0) | 347 (51.4) | 140 (56.0) | ||||
| TT | 49 (14.5) | 26 (17.3) | 65 (9.6) | 33 (13.2) | ||||
| IL1B rs1143633 | 0.71 (0.51 to 0.99) | 0.04 | 0.75 (0.58 to 0.96) | 0.02 | ||||
| GG | 128 (53.6) | 62 (63.9) | 267 (49.3) | 106 (55.8) | ||||
| GA | 67 (28.0) | 25 (25.8) | 205 (37.8) | 72 (37.9) | ||||
| AA | 44 (18.4) | 10 (10.3) | 70 (12.9) | 12 (6.3) | ||||
Continuous variables presented as mean (SD), categorical variables as % frequencies. QTc = corrected QT interval; CABG = coronary artery bypass graft surgery; IL1B = interleukin-1β; LVEF = left ventricular ejection fraction; OR (95% CI) = univariate odds ratio (95% confidence interval) evaluating the odds in cases (prolonged postoperative QTc group) compared with the odds in controls. ORs for continuous variables reflect: a, per each additional year; b, per each additional LVEF percentage point; c, per each additional minute. ORs for self-reported ethnicity evaluate the odds of prolonged postoperative QTc in patients self-identified as black or of other ancestry compared with the odds in white patients as a reference group (set as 1). ORs for procedure type evaluate the odds of prolonged postoperative QTc in patients undergoing CABG or CABG/valve surgery compared with the odds in patients undergoing isolated valve surgery as a reference (set as 1)