[Effect of nifedipine and enalapril on cardiac autonomic activity in elderly hypertensive patients]

Inhibitory effects of azelnidipine tablets on morning hypertension

BACKGROUND

Morning hypertension is a risk factor for cardiovascular and cerebrovascular events. Furthermore, it is a useful measure for definitive diagnosis of hypertension, and patients who self-assess their own blood pressure (BP) in the morning tend to exhibit better compliance with antihypertensive medication than those who do not.

OBJECTIVE

The objective of this analysis was to determine the BP- and pulse rate-lowering effects of azelnidipine, a long-acting dihydropyridine calcium antagonist administered once daily in the morning.

METHODS

We conducted the Azelnidipine Treatment for Hypertension Open-label Monitoring in the Early morning (At-HOME) Study by surveying patients who were taking azelnidipine. According to the study protocol, high systolic BP (SBP) was defined as ≥135 mmHg when measured at home in the morning and ≥140 mmHg when measured at the clinic during the day. A total of 5,433 hypertensive patients, who were registered at 1,011 medical institutions across Japan, were enrolled in the study. Data obtained from 4,852 of these patients (mean age, 64.8 years; female, 52.9 %; previous medication with other antihypertensive agents used concomitantly with the present study agent, 45.5 %) were used for efficacy analysis.

RESULTS

At baseline, the subjects' mean [± standard deviation] SBP/diastolic BP values at home in the morning, at the clinic during the day, and at home in the evening were 156.9 ± 16.4/89.7 ± 12.0, 157.5 ± 18.7/89.1 ± 13.3, and 150.2 ± 17.6/85.6 ± 12.2 mmHg, respectively. The mean pulse rates were 72.7 ± 10.7, 74.9 ± 11.2, and 72.5 ± 9.6 beats/min, respectively. Patients whose BP was defined as high accounted for 83.4 % of the study population, whereas 9.9 % had 'masked' hypertension, defined as SBP of ≥135 mmHg at home in the morning and <140 mmHg at the clinic. However, from 4 weeks after initiation of azelnidipine treatment till the end of the study at week 16, all three daily BP determinations were significantly (p < 0.0001) lowered, and pulse rates at home in the morning, at the clinic, and at home in the evening were similarly and significantly reduced (by -3.7 ± 8.0, -3.5 ± 9.5, and -3.5 ± 7.3 beats/min, respectively). Whereas achievement of home SBP of <135 mmHg in the morning was noted in only 6.6 % of patients before the start of azelnidipine treatment, this was noted in 43.3 % after 16 weeks. Meanwhile, achievement of clinic SBP of <140 mmHg was increased from 12.9 % of patients to 56.1 % of patients at the same timepoints. After azelnidipine treatment, 32.2 % of patients had well-controlled hypertension in both the home and clinic settings. Adverse drug reactions occurred in 2.92 % of patients (154/5,265). All adverse drug reactions were as expected for the calcium antagonist class of agents.

CONCLUSION

These data suggest that azelnidipine controlled morning hypertension well. Furthermore, azelnidipine reduced pulse rates significantly.

Autonomic nervous system adjustment (ANSA) in patients with hypertension treated with enalapril

BACKGROUND AND AIM

Reduced baroreflex sensitivity (BRS), decreased heart rate variability (HRV) and increased blood pressure (BP) variability have serious consequences for target organ damage in patients with hypertension, beside the BP level. The study was aimed to evaluate acute and long-term effects of enalapril, on BRS and HRV in individuals with prehypertension and mild essential hypertension.

METHODOLOGY

We enrolled in the study 85 patients (male 53%, age 42-67) with prehypertension and mild hypertension (systolic blood pressure ≥120 mmHg or diastolic blood pressure ≥80 mmHg). All patients were tested before, 30 minutes after first oral enalapril dose and three weeks after monotherapy with enalapril. The methodology included: beat to beat HRV analysis, BRS measurements with sequence technique, ECG with short term and 24-hour HRV analysis, 24-hour ambulatory blood pressure monitoring with systolic and diastolic BP variability analysis. Patients were divided into groups with sympathetic or vagal predominance based on Autonomic Nervous System Adjustment (ANSA) method.

RESULTS

1) 30 min after initial dose enalapril significantly and effectively reduced systolic BP with shift towards the parasympathetic predominance as reflected in decreased heart rate and low frequency (LF) to high frequency (HF) ratio (LF/HF ratio); 2) chronic enalapril therapy effectively reduced BP, including both systolic BP, diastolic BP and pulls pressure, had positively influence on dipping status, but did not significantly change BP variability; 3) in the whole patient group chronic enalapril therapy did not significantly change HRV, but it significantly decreased LF(nu) in the patient with high basal sympathetic activity, and significantly increased LF(nu) in patients with high basal vagal activity; enalapril also significantly decreased HF (nu) in patients with high basal parasympathetic activity; 4) despite initial, transit changes in maximal and minimal slope of BRS enalapril did not significantly affect sensitivity of spontaneous baroreflex activation.

CONCLUSION

Initial enalapril dose significantly reduced systolic BP and had beneficial effects on autonomic tone and baroreflex sensitivity. Chronic enalapril therapy effectively reduced BP without significant influence on BRS, but had significant autonomic effects on HRV when initial autonomic profile in each patient was analyzed by ANSA. Analyzed by ANSA method chronic enalapril therapy managed to retrieve disturbed sympathovagal balance and established autonomic equilibrium.

Antihypertensive drugs and sympathetic nervous system

Several studies have demonstrated that essential hypertension is accompanied by sympathetic activation, which contributes to blood pressure elevation. Sympathetic activation also has adverse consequences in hypertensive patients beyond initiating blood pressure elevation. There is evidence that neural vasoconstriction has metabolic effects in skeletal muscle, impairing glucose delivery to muscles. In the liver, retarding of post prandial clearance of lipids contributes to hyperlipidemia. Cardiac sympathetic activation is a probable cause of sudden death in hearth failure. A trophic effect of sympathetic activation on cardiovascular growth is also likely, contributing to the development of left ventricular hypertrophy. Consequently, one of the major aims of antihypertensive therapy should be to attenuate sympathetic tone. It is possible that, among the antihypertensive drugs available, those inhibiting the sympathetic nervous system might best reduce cardiovascular risk.