Table 2.
Demographic, clinical, and laboratory characteristics of the study participants who were able to perform maximal exercise, stratified by the presence or absence of chronotropic incompetence
| Characteristic | Chronotropic Incompetence |
P-value* | |
|---|---|---|---|
| Absent (n = 27) | Present (n = 81) | ||
| Age (years) | 65±10 | 64±12 | 0.68 |
| Women | 19(70%) | 57(70%) | 0.99 |
| Race | 0.75 | ||
| • White | 16(5 9%) | 40(49%) | |
| • African-American | 9(33%) | 34(42%) | |
| • Other | 2(7%) | 7(9%) | |
| Comorbidities** | |||
| • Coronary artery disease | 7(26%) | 33(41%) | 0.17 |
| • Hypertension | 20(74%) | 64(79%) | 0.59 |
| • Hyperlipidemia | 15(56%) | 50(62%) | 0.57 |
| • Diabetes mellitus | 6(22%) | 29(36%) | 0.19 |
| • Chronic kidney disease | 3(11%) | 31(38%) | 0.008 |
| • Smoker | 13(48%) | 23(28%) | 0.059 |
| • Atrial fibrillation | 6(22%) | 26(32%) | 0.33 |
| • Obesity | 15(56%) | 46(57%) | 0.91 |
| • Chronic obstructive pulmonary disease | 8(29%) | 36(44%) | 0.18 |
| New York Heart Association functional class | 0.055 | ||
| • I | 7(26%) | 6(7%) | |
| • II | 9(33%) | 35(43%) | |
| • III | 10(41%) | 40(49%) | |
| Heart rate (beats/min) | 77±15 | 70±13 | 0.03 |
| Systolic blood pressure (mm Hg) | 122±21 | 126±21 | 0.39 |
| Diastolic blood pressure (mm Hg) | 74±11 | 72±11 | 0.52 |
| Pulse pressure (mm Hg) | 48±11 | 57±17 | 0.01 |
| Body mass index (kg/m2) | 31±9 | 32±8 | 0.43 |
| Serum sodium (mEq/L) | 139±3 | 139±3 | 0.78 |
| Blood urea nitrogen (mg/dl) | 18±9 | 24±16 | 0.07 |
| Serum creatinine (mg/dl) | 0.9±0.4 | 1.5±1.2 | 0.02 |
| Estimated glomerular filtration rate (ml/min/1.73m2) | 79±28 | 56±24 | < 0.001* |
| Fasting blood glucose (mg/dl) | 118±80 | 127±59 | 0.58 |
| Hemoglobin (g/dl) | 12.4±1.4 | 12.2±1.6 | 0.57 |
| Log B-type natriuretic peptide (pg/ml) | 4.1±1.3 | 5.3±1.2 | < 0.001* |
| Medications | |||
| • Angiotensin converting enzyme inhibitor or angiotensin receptor blocker | 16(5 9%) | 45(56%) | 0.74 |
| • β-blocker | 13(48%) | 50(62%) | 0.08 |
| • Calcium channel blocker | 6(22%) | 30(37%) | 0.16 |
| • Nitrate | 1(4%) | 13(16%) | 0.18 |
| • Loop diuretic | 9(33%) | 47(58%) | 0.03 |
| • Thiazide diuretic | 11(41%) | 18(22%) | 0.06 |
| • Statin | 14(52%) | 46(57%) | 0.66 |
| • Aspirin | 11(41%) | 31(38%) | 0.82 |
Values expressed as mean ± standard deviation, unless otherwise specified
Statistically significant (q < 0.05) after adjustment for false discovery rate
Coronary artery disease was determined using defined protocol that included physician-documented history of coronary disease; known coronary stenosis >50%; history of myocardial infarction, percutaneous coronary intervention, or coronary artery bypass grafting; or abnormal stress test results consistent with myocardial ischemia. Hypertension was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg, physician-documented history of hypertension, or current use of antihypertensive medications. Hyperlipidemia was defined as physician-documented history of hyperlipidemia or current use of lipid-lowering medications. Obesity was defined as body mass index >30 kg/m2.