What is the clinical evidence from this study?

Study design: RCT. Population: Essential hypertension (n=29). Intervention: Nifedipine vs. Enalapril. Primary outcome: Percent change in low-frequency coefficient of component variance (LFCCV) during tilt test (p=<0.01).

January 1, 1997Open Access

Effects of Nifedipine and Enalapril on Cardiac Autonomic Nervous Function during the Tilt Test in Elderly Patients with Hypertension.

Q: What are the key findings of this study?

Long-term treatment with nifedipine markedly impaired cardiac sympathetic response during the tilt test, significantly decreasing the percent change in LFCCV from 66.2% to -3.3% (p<0.01), whereas enalapril maintained autonomic function.

JOJunko OkabayashiAkebono Clinic KMKozo MatsubayashiKyoto University YDYoshinori DoiGeneral Cardiology

Key Result

Long-term treatment with nifedipine markedly impaired cardiac sympathetic response during the tilt test, significantly decreasing the percent change in LFCCV from 66.2% to -3.3% (p<0.01), whereas enalapril maintained autonomic function.

Study Design

Type

RCT (n=29)

Randomization

Randomized

Multicenter

Yes

Structured PICO

Does nifedipine compared to enalapril alter cardiac autonomic nervous function during the tilt test in elderly patients with hypertension?

Population

29 elderly outpatients (mean age 69 years, 41.4% female) with essential hypertension, free of severe cardiovascular or renal comorbidities, were randomized to nifedipine or enalapril for 3 months.

Intervention

Nifedipine (sustained release) 10 mg oral twice daily for 3 months

Comparator

Enalapril 5 mg oral once daily for 3 months

Outcome

Cardiac autonomic nervous function during postural changes (tilt test) assessed by power spectral analysis of heart rate variability (LFCCV, HFCCV, L/H) and humoral factorssurrogate

Long-term administration of nifedipine, but not enalapril, impairs the cardiac sympathetic response and may induce orthostatic hypotension during tilting in elderly hypertensive patients.

Main Result

p-value: p=<0.01

Limitations

Small sample size
Lack of a placebo control group

Abstract

To clarify the effects of nifedipine and enalapril on cardiac autonomic nervous function during postural changes, power spectral analysis of heart rate variability and humoral factors was performed during tilt tests before and after 3 months of drug administration. The study group consisted of 29 elderly patients with hypertension (mean age, 69 yr), who were divided into two groups: 15 patients received nifedipine (group N) and 14 received enalapril (group E). In group N, systolic blood pressure was significantly decreased and the percent changes in low-frequency coefficient of component variance, normalized low-frequency: high-frequency ratio, and plasma norepinephrine concentration were significantly altered by nifedipine administration. Group E, in contrast, showed no significant decrease in SBP, and only the percent change in high-frequency coefficient of component variance increased significantly after enalapril administration. These results suggest that cardiac autonomic nervous function is markedly impaired during the tilt test after long-term treatment with nifedipine, whereas it is well-maintained after long-term treatment with enalapril.

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