Table 2.
Association of QT and RR Time Intervals Variables Prior to, During, and Following Arousals With All-Cause and Cardiovascular Mortality
| Variables | All-Cause Mortality (n = 1,000) |
Cardiovascular Mortality (n = 348) |
Noncardiovascular Mortality (n = 552) |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Univariate Analysis |
Multivariable Analysis |
Univariate Analysis |
Multivariable Analysis |
Univariate Analysis |
Multivariable Analysis |
|||||||
| HR (95% CI) | P Value | HR (95% CI) | P Value | HR (95% CI) | P Value | HR (95% CI) | P Value | HR (95% CI) | P Value | HR (95% CI) | P Value | |
| Prior to arousal | ||||||||||||
| QTVi (SD) | 1.19 (0.86-1.64) | .287 | 1.20 (0.85-1.71) | .321 | 1.81 (1.06-2.18) | .029 | 1.66 (0.94-2.95) | .088 | 0.95 (0.63-1.41) | .789 | 1.01 (0.65-1.56) | .978 |
| QTVi ≥ 0.42 | 1.03 (0.91-1.17) | .616 | 1.09 (0.95-1.25) | .238 | 1.19 (0.96-1.46) | .115 | 1.23 (0.98-1.55) | .074 | 0.96 (0.82-1.12) | .593 | 1.02 (0.86-1.21) | .861 |
| Arousal onset | ||||||||||||
| QTVi (SD) | 1.80 (1.35-2.41) | < .001 | 1.47 (1.07-2.02) | .029 | 3.47 (2.11-5.72) | < .001 | 2.47 (1.43-4.25) | .001 | 1.28 (0.89-1.82) | .169 | 1.12 (0.76-1.67) | .693 |
| QTVi ≥ 0.42 | 1.25 (1.09-1.43) | .001 | 1.20 (1.04-1.38) | .012 | 1.49 (1.19-1.86) | < .001 | 1.29 (1.01-1.65) | .043 | 1.13 (0.95-1.34) | .161 | 1.11 (0.92-1.32) | .279 |
| Postarousal onset | ||||||||||||
| QTVi (SD) | 1.68 (1.15-2.44) | .007 | 1.37 (0.90-2.07) | .138 | 3.02 (1.59-5.72) | < .001 | 2.09 (1.04-4.18) | .039 | 1.23 (0.77-1.95) | .385 | 1.10 (0.66-1.85) | .763 |
| QTVi ≥ 0.42 | 1.05 (0.92-1.20) | .455 | 1.02 (0.89-1.19) | .745 | 1.17 (0.94-1.46) | .159 | 1.05 (0.83-1.34) | .668 | 0.99 (0.84-1.17) | .916 | 1.01 (0.84-1.22) | .883 |
Multivariable analysis was adjusted for age, history of stroke, atrial fibrillation, myocardial infarction/coronary artery disease, congestive heart failure, transient ischemic attack, diabetes, hypertension, COPD, asthma and Parkinson disease, mean heart rate, mean respiratory rate, Physical Activity Scale for Elderly, systolic and diastolic BPs, time of sleep spent below 90% oxygen saturation, BMI, apnea-hypopnea index, arousal index, average corrected QT, arousal burden, and drink and smoking habit. QT variability index (QTVi) values were dichotomized at the 75th percentile of the arousal-onset QTVi. Boldface indicates a P value with statistical significance. HR = hazard ratio.