Table 1.
Baseline Demographic and Clinical Characteristics
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|
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|---|---|---|---|---|
| Variable | All Patients (n=537) |
Acute Myocardial Infarction
|
p | |
| YES (n=47, 9%) | NO (n=490, 91%) | |||
|
| ||||
| Demographics | ||||
| Age (years) | 57 ± 16 | 60 ± 15 | 57 ± 17 | .145 |
| Sex (Male) | 302 (56%) | 26 (55%) | 276 (56%) | .894 |
| Race (White) | 297 (55%) | 40 (85%) | 257 (52%) | .000 |
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| Past Medical History | ||||
| Hypertension | 354 (66%) | 27 (57%) | 327 (68%) | .160 |
| Diabetes | 131 (24%) | 13 (28%) | 118 (24%) | .236 |
| Dyslipidemia | 190 (35%) | 18 (38%) | 172 (36%) | .706 |
| Ever Smoker | 311 (58%) | 24 (51%) | 287 (59%) | .457 |
| Coronary Artery Disease | 166 (31%) | 13 (28%) | 153 (32%) | .577 |
| Myocardial Infarction | 135 (25%) | 9 (19%) | 126 (26%) | .301 |
| Heart Failure | 77 (14%) | 6 (13%) | 71 (15%) | .723 |
| Prior PCI/Stent | 122 (23%) | 15 (30%) | 107 (22%) | .003 |
| Prior CABG | 43 (8%) | 6 (13%) | 37 (8%) | .169 |
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| Presenting Vital Signs | ||||
| Heart Rate (bpm) | 86 ± 23 | 78 ± 18 | 87 ± 24 | .011 |
| Breathing Rate (breath/min) | 18 ± 3 | 20 ± 4 | 18 ± 3 | .013 |
| Systolic BP (mmHg) | 147 ± 30 | 147 ± 34 | 147 ± 29 | .933 |
| Diastolic BP (mmHg) | 87 ± 18 | 90 ± 21 | 87 ± 18 | .247 |
| Oxygen Saturation (%) | 98 ± 5 | 98 ± 3 | 98 ± 5 | .898 |
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| ||||
| Laboratory Values at ED | ||||
| Initial Positive Troponin | 68 (13%) | 13 (28%) | 54 (11%) | .001 |
| Sodium | 138 ± 3 | 138 ± 3 | 138 ± 3 | .985 |
| Potassium | 3.9 ± 0.5 | 3.8 ± 0.5 | 3.9 ± 0.5 | .234 |
| Calcium | 9.0 ± 0.6 | 8.8 ± 0.7 | 9.0 ± 0.6 | .021 |
| Magnesium | 1.9 ± 1.2 | 1.8 ± 0.3 | 1.9 ± 1.3 | .681 |
| Glucose | 135 ± 70 | 145 ± 43 | 134 ± 72 | .289 |
| Creatinine | 1.2 ± 1.3 | 1.1 ± 0.9 | 1.2 ± 1.4 | .584 |
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| ECG Variables | ||||
| Mean RR | 768 ± 199 | 834 ± 239 | 761 ± 194 | .017 |
| # of beats analyzed | 13 ± 4 | 12 ± 3 | 13 ± 4 | .035 |
| HR/BR Ratio (median [IQR]) | 4.2 (3.4–5.1) | 3.8 (3.0–4.3) | 4.3 (3.6–5.3) | .034 |
| HR/BR Ratio (odd vs. even) | 49% vs. 51% | 47% vs. 53% | 49% vs. 51% | .735 |
| High Frequency Noise | 6.4 ± 3.8 | 7.5 ± 5.0 | 6.3 ± 3.7 | .032 |
| Fiducial Point Lability | 8.5 ± 6.7 | 10.7 ± 8.0 | 8.3 ± 6.5 | .050 |
| R Peak Lability | 14.3 ± 8.4 | 13.0 ± 7.0 | 14.4 ± 8.5 | .264 |
| TWA (mV) | .0109 ± .0098 | .0163 ± .0144 | .0103 ± .0091 | .007 |
| NARV (mV) | .0179 ± .0119 | .0225 ± .0167 | .0174 ± .0113 | .005 |