Postural Response of Low-Frequency Component of Heart Rate Variability: Results

Follow-up Results
During a mean follow-up period of 99 ± 23 months (follow-up range, 14 to 131 months), 25 patients (10%) died. Thirteen patients died from cardiac causes (acute myocardial infarction, 9 patients; sudden cardiac death, 4 patients), and 12 died from noncardiac causes (fatal stroke, 6 patients; malignancies, 3 patients; renal failure, 1 patient; liver cirrhosis, 1 patient; and collagen disease, 1 patient). The mean survival duration in the 25 nonsurvivors was 50 ± 28 months (range, 2 to 92 months).
Baseline Characteristics of Patients Grouped by Subsequent Survival State
When the patients were grouped by subsequent survival state, some baseline clinical data showed a significant group difference (Table 1). Compared with surviving patients, patients who subsequently died from cardiac causes were older, had lower body mass index levels, had lower left ventricular ejection fractions, and were more likely to have significant stenosis in multiple coronary arteries at baseline, while patients who subsequently died from noncardiac causes were older but were comparable for other clinical variables. However, the fractions of patients undergoing coronary interventions and those receiving regular medications of (p-blockers and angiotensin-converting enzyme inhibitors during the follow-up period did not differ among the groups. canadian family pharmacy

Significant group differences also were observed in HRV measures at baseline (Table 2). Compared with surviving patients, patients dying from noncardiac causes had lower HF values in both the supine and tilt positions, although patients who died from cardiac causes showed no significant differences in any HRV measures. Compared with control subjects, patients who died from cardiac causes had lower total power values in the supine position and patients who died from noncardiac causes had lower HF values in both the supine and tilt positions. Differences in the response of HRV measures to HUTT, however, did not reach a significant level. Also, no significant difference was detected in BPs or in their responses to the HUTT.
Table 1—Clinical Characteristics of Patients Grouped by Subsequent Survival State

Characteristics Cardiac Death (n = 13) Noncardiac Death (n = 12) Survivors (n = 225) p Value
BaselineAge, yr GO±CC6 66 ± 6f 56 ± 10 < 0.001
Male 11 (85) 9(75) 161 (72) NS
Hypertension 3 (23) 2(17) 39 (17) NS
Smoking 5 (38) 5 (42) 126 (56) NS
LDL cholesterol, mg/dL 115 ± 23 136 ± 33 116 ± 40 NS
HDL cholesterol, mg/dL 41 ± 13 7±73 43 ± 13 NS
Diabetes mellitus 3 (23) 1(8) 48 (21) NS
Body mass index 21 ± 2t 23 ± 2 23 ± 3 0.039
Previous myocardial 9(69) 6 (50) 83 (37) NS
infarctionEjection fraction, % ъ±65 63 ± 11 64 ± 10 0.017
LVEDP, mm Hg 14 ± 4 12 ± 6 13 ± 5 NS
Diseased coronary artery 0 vessels 1(8) 3 (26) 71 (32)
1 vessel 5 (38) 4 (33) 109 (48)
2 vessels 5 (38) 4 (33) 27 (12)
3 vessels 2 (16) 1 (8) 18 (8)
Therapies during follow-up PTCA 0 (0) 1 (8) 25 (11) NS
CABG 2 (15) 1 (8) 4 (2) NS
p-blocker 2 (15) 3 (25) 59 (26) NS
ACE inhibitor 2 (15) 0 (0) 24(11) NS

Table 2—HRV Measures and BP During HUTT in Patients and Control Subjects

Variables Cardiac Death (n = 13) Noncardiac Death (n = 12) Survivors (n = 225) Control Subjects (n = 90) p Value
Supine
Mean R-R, ms 960 ± 179 841 ± 142 934 ± 146 957 ± 144 NS
Total power, ln(ms2) 5.81 ± 1.13t 6.26 ± 0.93 6.43 ± 0.85 6.50 ± 0.81 0.0408
HF, ln(ms2) 3.89 ± 1.62 2.99 ± 2.00tJ 4.43 ± 1.20 4.64 ± 1.16 < 0.001
LF, ln(ms2) 3.97 ± 1.04 3.72 ± 1.38 4.48 ± 1.14 4.51 ± 1.08 NS
LFnu 53.6 ± 23.1 64.1 ± 21.2 51.3 ± 22.0 47.4 ± 20.5 NS
Systolic BP, mm Hg 126 ± 15 121 ± 16 122 ± 15 122 ± 15 NS
Diastolic BP, mm Hg 8±37 ±67 0±57 75 ± 12 NS
Tilt
Mean R-R, ms 840 ± 174 730 ± 107 23±5

9

7

829 ± 123 NS
Total power, ln(ms2) 5.99 ± 1.41 5.86 ± 0.95 6.14 ± 0.86 6.24 ± 0.79 NS
HF, ln(ms2) 3.48 ± 1.44 2.28 ± 1.78TI 3.55 ± 1.27 3.64 ± 1.23 0.008
LF, ln(ms2) 4.35 ± 1.31 3.55 ± 0.99 4.21 ± 1.11 4.38 ± 0.97 NS
LFnu 65.4 ± 14.8 75.6 ± 17.1 62.5 ± 22.6 64.1 ± 21.5 NS
Systolic BP, mm Hg 117 ± 18 115 ± 23 117 ± 16 117 ± 16 NS
Diastolic BP, mm Hg ±37 3±67 2±67 77 ± 12 NS
Change (tilt — supine)
Mean R-R, ms — 120 ± 100 — 111 ± 56 — 139 ± 76 — 128 ± 74 NS
Total power, ln(ms2) 0.18 ± 1.02 — 0.40 ± 0.79 — 0.29 ± 0.73 — 0.26 ± 0.70 NS
HF, ln(ms2) — 0.42 ± 0.66 — 0.72 ± 1.16 — 0.89 ± 1.16 — 1.01 ± 1.19 NS
LF, ln(ms2) 0.38 ± 0.77 — 0.14 ± 0.88 — 0.27 ± 0.91 — 0.13 ± 0.94 NS
LFnu 11.8 ± 18.4 11.5 ± 25.4 11.2 ± 24.5 16.7 ± 23.6 NS
Systolic BP, mm Hg — 7 ± 15 — 5 ± 15 — 5 ± 12 — 4 ± 12 NS
Diastolic BP, mm Hg 0 ± 7 1 ± 9 1 ± 8 2 ± 8 NS
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