Table 1. Characteristics of participants with low (SDNN < 100 ms) versus normal (SDNN ≥ 100 ms) heart rate variability.
| Variable | Low HRV (n = 264) |
Normal HRV (n = 598) |
p value |
|---|---|---|---|
| Demographic factors | |||
| Age (years) | 66 ± 10 | 69 ± 11 | 0.235 |
| Male sex | 204 (77) | 500 (84) | 0.027 |
| High school graduate | 226 (86) | 524 (88) | 0.416 |
| Living alone | 88 (33) | 219 (37) | 0.353 |
| Ethnicity | |||
| White | 137 (52) | 363 (61) | 0.025 |
| Black | 60 (23) | 88 (15) | |
| Asian | 32 (12) | 73 (12) | |
| Other | 34 (13) | 74 (12) | |
| Cardiac history | |||
| Prior myocardial infarction | 143 (55) | 323 (54) | 0.937 |
| Coronary artery bypass surger | 106 (40) | 207 (35) | 0.112 |
| Percutaneous revascularization | 95 (36) | 241 (40) | 0.232 |
| Comorbid conditions | |||
| Hypertension | 199 (75) | 416 (70) | 0.095 |
| Stroke | 42 (16) | 83 (14) | 0.447 |
| Chronic heart failure | 57 (22) | 80 (13) | 0.003 |
| Chronic obstructive pulmonary disease | 57 (22) | 79 (13) | 0.002 |
| Metabolic factors | |||
| History of diabetes | 102 (39) | 119 (20) | <0.001 |
| Systolic blood pressure (mmHg) | 135 ± 22 | 133 ± 21 | 0.189 |
| Low-density lipoprotein cholesterol (mg/dL) | 105 ± 35 | 104 ± 32 | 0.538 |
| High-density lipoprotein cholesterol (mg/dL) | 46 ± 15 | 46 ± 14 | 0.937 |
| Body mass index (kg/m2) | 28.9 ± 5.8 | 28.1 ± 4.8 | 0.026 |
| Health habits | |||
| Current smoking | 64 (24) | 103 (17) | 0.017 |
| Alcohol score | 2.4 ± 2.5 | 2.2 ± 2.4 | 0.147 |
| Physically active | 156 (59) | 392 (66) | 0.075 |
| Medications | |||
| Beta blocker | 160 (61) | 353 (59) | 0.664 |
| Statin | 167 (63) | 393 (66) | 0.485 |
| Angiotensin-converting enzyme inhibitor | 123 (47) | 296 (49) | 0.431 |
| Aspirin | 216 (82) | 477 (80) | 0.484 |
Data are given as absolute values with percent values in parentheses or mean ± SD