Shortening baroreflex delay in hypertrophic cardiomyopathy patients – an unknown effect of β‐blockers

Abstract

Keywordsbaroreflex delay, baroreflex sensitivity, b-blocker, heart rate variability, hypertrophic cardiomyopathy ----------------------------------------------------------------------- AIMSHypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy and impaired diastolic and systolic function. Abnormal sympathetic-parasympathetic balance is a potential stimulus for left ventricular hypertrophy in HCM patients. b-Blockers are routinely used in HCM for their strong negative inotropic effect; however, these drugs also influence the sympathetic-parasympathetic balance. This study aimed to determine the autonomic control of the cardiovascular system and the autonomic effects of b-blockers in HCM patients treated or untreated with b-blockers. METHODSAmong 51 HCM outpatients (18-70 years old; 29 men) there were 19 individuals with no medication and 32 subjects treated with a b-blocker. Fourteen age-and gender-matched (23-70 years old; nine men) healthy volunteers were enrolled in the control group. Continuous, non-invasive finger blood pressure was recorded during supine rest for 30 min. Autonomic regulation of the cardiovascular system was measured by heart rate variability and spontaneous baroreflex function (cross-correlation sequence method). RESULTSThe mean pulse interval, time domain and spectral measures of heart rate variability and baroreflex sensitivity were comparable between HCM patients, treated or not with b-blockers, and the control group. However, the delay of the baroreflex was significantly longer in HCM patients who were not treated with b-blockers [2.0 (1.6-2. CONCLUSIONSHypertrophic cardiomyopathy not treated with b-blockers is accompanied by prolonged baroreflex delay. The use of b-blockers normalizes this delay. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• b-Blockers are routinely used in pharmacological therapy in patients with hypertrophic cardiomyopathy (HCM). These drugs affect the sympathetic modulation of the cardiovascular system by blocking b-adrenergic receptors. Patients with HCM have impaired autonomic control of the heart, which can be measured by indices of heart rate variability, blood pressure variability or baroreflex function. WHAT THIS STUDY ADDS• The baroreflex delay, which is the time necessary for the adaptive response of the sinus node to an alteration in vagal tone triggered by a preceding change in blood pressure, is prolonged in untreated HCM patients compared with healthy peers. The baroreflex delay in HCM patients who receive b-blockers is comparable to that of healthy subjects and is significantly shorter than that in untreated HCM patients. This study extends our knowledge about the specific effect of b-blockers on the baroreflex function in HCM patients.

Heart rate variability and haemodynamic function in individuals with hypertrophic cardiomyopathy

“…In agreement with the present study, Katarzynska‐Szymanska et al (2013) found no significant differences in HRV measures between the HCM and healthy control groups. Although the study recruited a higher number of individuals (51 participants) with HCM, there were no differences in all spectral components of HRV between individuals with HCM and controls.…”

“…Although the study recruited a higher number of individuals (51 participants) with HCM, there were no differences in all spectral components of HRV between individuals with HCM and controls. ECG, as used in the present study, is the gold standard method to detect HRV accurately as it directly records the electrical activity of the heart whereas photoplethysmography (PPG), which was used by Katarzynska‐Szymanska et al (2013), records HRV indirectly by detecting blood volume and it is sensitive to body motion artifacts (Jan et al, 2019; Jeyhani et al, 2015).…”

“…It has been previously reported that individuals with HCM have increased sympathetic (SNS) activity and/or hypersensitivity of the myocardium to catecholamines (Ajiki et al, 1993; Perloff, 1981; Seggewiss et al, 2009; Tanabe et al, 1995). The increase in the adrenergic drive is believed to be a potential stimulus for left ventricular hypertrophy (LVH), increased heart rate and blood pressure, and SCD in HCM (Katarzynska‐Szymanska et al, 2013). There is also evidence to show reduction in parasympathetic (PNS) activity in HCM (Ajiki et al, 1993; Bonaduce et al, 1997; Counihan et al, 1993; Döven et al, 2001; Limbruno et al, 1998; Tanabe et al, 1995) or reduction in SNS activity (Fei et al, 1995).…”

Application of non‐invasive bioreactance to assess hemodynamic function in patients with hypertrophic cardiomyopathy

“…Cardiac output was significantly reduced possibly due to attenuation of heart rate caused by beta blocker medication. It has been suggested that HCM patients treated with beta blockers have baroreflex sensitivity comparable to healthy individuals, thus effectively adapting to an alteration in vagal tone triggered by a preceding change in blood pressure (Katarzynska‐Szymanska et al, 2013 ). Whilst this assumption supports our findings under resting conditions, beta‐blockers have been reported to attenuate blood pressure response to exercise (Chen et al, 1999 ).…”

Deceleration and acceleration capacities of heart rate in patients with hypertrophic cardiomyopathy: results of a five-year prospective study

“…При ГКМП, в отличие от пациентов с ИБС, на настоящий момент ни одна из электрокардиографических методик, оценивающих вегетативный дисбаланс -ТРС, ва-риабельность ритма сердца (ВРС), не показала своей значимости в прогнозировании развития ВСС [20][21][22]. По данным El-Menyar A, et al (2008), ТРС тесно связана с влиянием барорефлекса [23], а по данным Katarzynska-Szymanska A, et al (2013), барорецепторная чувствительность при ГКМП не отличается от таковой у здоровых лиц [24]. Изменение ВРС, по мнению многих авторов, больше связано c тяжестью ХСН, чем с частотой ВСС [25,26].…”