Reliability of heart rate as neuroadrenergic marker in the metabolic syndrome

Sympathetic overactivity, hypertension and cardiovascular disease: state of the art

Cardiovascular disease (CVD) remains the most prevalent cause of premature death worldwide. It had been suspected for decades that increased activity of the sympathetic nervous system (SNS) might play a pathogenetic role in the development and progression of hypertension, heart failure (HF) and CVD. The use of microneurographic techniques to directly assess the SNS has allowed this field to advance considerably in recent years. We now have compelling evidence for a key role of sympathetic overactivity in the pathogenesis and progression of hypertension and associated hypertension-mediated organ damage (such as endothelial dysfunction, arterial stiffness and left ventricular hypertrophy), HF (with or without reduced left ventricular ejection fraction). Sympathetic overactivity also drives increased cardiovascular risk in the settings of obesity, metabolic syndrome, chronic kidney disease and obstructive sleep apnoea, among other conditions. Thus, sympathetic overactivity is an important factor that drives patients through the CVD continuum, from the early appearance of cardiovascular risk factors, to impairments of the structure and function of components of the heart and arteries, to established CVD, and ultimately to a life-threatening cardiovascular event. A deeper understanding of the role of sympathetic overactivity in the pathogenesis of CVD and HF will support the optimization of therapeutic interventions for these conditions.

Efficacy of intensive lipid-lowering therapy with statins stratified by blood pressure levels in patients with type 2 diabetes mellitus and retinopathy: Insight from the EMPATHY study

Intensive lipid-lowering therapy is recommended in individuals exhibiting type 2 diabetes mellitus (T2DM) with microvascular complications (as high-risk patients), even without known cardiovascular disease (CVD). However, evidence is insufficient to stratify the patients who would benefit from intensive therapy among them. Hypertension is a major risk factor, and uncontrolled blood pressure (BP) is associated with increased CVD risk. We evaluated the efficacy of intensive vs. standard statin therapy for primary CVD prevention among T2DM patients with retinopathy stratified by BP levels. We used the dataset from the EMPATHY study, which compared intensive statin therapy targeting low-density lipoprotein cholesterol (LDL-C) levels of <70 mg/dL and standard therapy targeting LDL-C levels ranging from ≥100 to <120 mg/dL in T2DM patients with retinopathy without known CVD. A total of 4980 patients were divided into BP ≥ 130/80 mmHg (systolic BP ≥ 130 mmHg and/or diastolic BP ≥ 80 mmHg, n = 3335) and BP < 130/80 mmHg (n = 1645) subgroups by baseline BP levels. During the median follow-up of 36.8 months, 281 CVD events were observed. Consistent with previous studies, CVD events occurred more frequently in the BP ≥ 130/80 mmHg subgroup than in the BP < 130/80 mmHg subgroup (P < 0.001). In the BP ≥ 130/80 mmHg subgroup, intensive statin therapy was associated with lower CVD risk (HR 0.70, P = 0.015) than standard therapy after adjustment. No such association was observed in the BP < 130/80 mmHg subgroup. The interaction between BP subgroup and statin therapy was significant. In conclusion, intensive statin therapy targeting LDL-C < 70 mg/dL provided benefits in primary CVD prevention when compared with standard therapy among T2DM patients with retinopathy and BP ≥ 130/80 mmHg.

Heart Rate in Patients with SARS-CoV-2 Infection: Prevalence of High Values at Discharge and Relationship with Disease Severity

The most common arrhythmia associated with COronaVIrus-related Disease (COVID) infection is sinus tachycardia. It is not known if high Heart Rate (HR) in COVID is simply a marker of higher systemic response to sepsis or if its persistence could be related to a long-term autonomic dysfunction. The aim of our work is to assess the prevalence of elevated HR at discharge in patients hospitalized for COVID-19 and to evaluate the variables associated with it. We enrolled 697 cases of SARS-CoV2 infection admitted in our hospital after February 21 and discharged within 23 July 2020. We collected data on clinical history, vital signs, laboratory tests and pharmacological treatment. Severe disease was defined as the need for Intensive Care Unit (ICU) admission and/or mechanical ventilation. Median age was 59 years (first-third quartile 49, 74), and male was the prevalent gender (60.1%). 84.6% of the subjects showed a SARS-CoV-2 related pneumonia, and 13.2% resulted in a severe disease. Mean HR at admission was 90 ± 18 bpm with a mean decrease of 10 bpm to discharge. Only 5.5% of subjects presented HR > 100 bpm at discharge. Significant predictors of discharge HR at multiple linear model were admission HR (mean increase = β = 0.17 per bpm, 95% CI 0.11; 0.22, p < 0.001), haemoglobin (β = −0.64 per g/dL, 95% CI −1.19; −0.09, p = 0.023) and severe disease (β = 8.42, 95% CI 5.39; 11.45, p < 0.001). High HR at discharge in COVID-19 patients is not such a frequent consequence, but when it occurs it seems strongly related to a severe course of the disease.

Effectiveness of statin intensive therapy in type 2 diabetes mellitus with high visit-to-visit blood pressure variability

BACKGROUND

Intensive lipid-lowering therapy is recommended in type 2 diabetes mellitus (T2DM) patients with target organ damage. However, the evidence is insufficient to stratify the patients who will benefit from the intensive therapy among them. High visit-to-visit variability in systolic blood pressure (SBP) is associated with increased risk of cardiovascular events. We investigated the effectiveness of intensive versus standard statin therapy in the primary prevention of cardiovascular events among T2DM patients with retinopathy stratified by visit-to-visit SBP variability.

METHODS

The standard versus intensive statin therapy for hypercholesterolemic patients with diabetic retinopathy study was the first trial comparing statin intensive therapy targeting low-density lipoprotein cholesterol (LDL-C) <70 mg/dl and standard therapy targeting LDL-C ≥100 to <120 mg/dl in T2DM patients with retinopathy without known cardiovascular disease. Using this dataset, we divided the patients into two subpopulations based on standard deviation (SD) and average real variability (ARV) of clinic SBP within the initial 6 months.

RESULTS

In a total of 4899 patients, 240 composite cardiovascular events were observed during a median follow-up of 37.3 months. In multivariable-adjusted model comparing intensive versus standard therapy, the hazard ratios for composite cardiovascular events were 0.64 (95% CI 0.45-0.90) and 1.21 (95% CI 0.82-1.80) in patients with high and low SBP variability as defined by SD, respectively. Interaction between SBP variability and statin therapy was significant (P = 0.018). The analysis using ARV of SBP showed similar results.

CONCLUSION

Statin intensive therapy targeting LDL-C <70 mg/dl had benefits in primary prevention of cardiovascular events compared with standard therapy among T2DM patients with retinopathy having high, but not low, visit-to-visit SBP variability.

Association of Urine Metanephrine Levels with CardiometaBolic Risk: An Observational Retrospective Study

No research has explored the role of catecholamine metabolites in the stratification of cardiovascular risk. We aimed to evaluate the relationship between urine metanephrines and cardiometabolic risk/complications. In this retrospective cross-sectional study, we collected the data of 1374 patients submitted to the evaluation of urine metanephrines at the City of Health and Science University Hospital of Turin between 2007 and 2015, mainly for investigating the suspicion of secondary hypertension or the secretion of an adrenal lesion. The univariate analysis showed associations between metanephrines and cardiometabolic variables/parameters, particularly considering noradrenaline metabolite. At univariate regression, normetanephrine was associated with hypertensive cardiomyopathy (OR = 1.18, 95% CI 1.11–1.25; p < 0.001) and metabolic syndrome (OR = 1.11, 95% CI 1.03–1.20; p = 0.004), while metanephrine was associated with hypertensive cardiomyopathy (OR = 1.23, 95% CI 1.06–1.43; p = 0.006) and microalbuminuria (OR = 1.30, 95% CI 1.03–1.60; p = 0.018). At multivariate regression, considering all major cardiovascular risk factors as possible confounders, normetanephrine retained a significant association with hypertensive cardiomyopathy (OR = 1.14, 95% CI 1.07–1.22; p < 0.001) and metabolic syndrome (OR = 1.10, 95% CI 1.02–1.19; p = 0.017). Moreover, metanephrine retained a significant association with the presence of hypertensive cardiomyopathy (OR = 1.18, 95% CI 1.01–1.41; p = 0.049) and microalbuminuria (OR = 1.34, 95% CI 1.03–1.69; p = 0.019). The study showed a strong relationship between metanephrines and cardiovascular complications/metabolic alterations. Individuals with high levels of these indirect markers of sympathetic activity should be carefully monitored, and they may benefit from an aggressive treatment to reduce the cardiometabolic risk.

Sympathetic overdrive in the metabolic syndrome: meta-analysis of published studies

OBJECTIVE

The microneurographic technique has shown that sympathetic overactivity may characterize patients with the metabolic syndrome. However, technical and methodological limitations of the studies prevented to draw definite conclusions. The present meta-analysis evaluated 16 microneurographic studies including 650 individuals, 444 metabolic syndrome patients and 206 healthy controls, respectively. The analysis was primarily based on muscle sympathetic nerve traffic (MSNA) quantified by microneurography in metabolic syndrome.

METHODS

Assessment was extended to the relationships of MSNA with an indirect neuroadrenergic marker, such as heart rate (HR), anthropometric variables, as BMI, waist-hip ratio and metabolic profile.

RESULTS

Metabolic syndrome individuals displayed MSNA values (means ± SEM) significantly greater than controls (58.6 ± 4.8 versus 41.6 ± 4.1 bursts/100 heart beats, P < 0.01). This result was independent on the concomitant presence of sleep apnea and drug treatment. MSNA was directly and significantly related to clinic SBP (r = 0.91, P < 0.01) but not to BMI (r = 0.17, P = NS), whereas no significant relationship was found between MSNA and metabolic variables included in the definition of metabolic syndrome. No significant correlation was found between MSNA and HR.

CONCLUSION

These data provide evidence that metabolic syndrome is characterized by a marked increase (about 30%) in MSNA. They also show that among the variables included in metabolic syndrome definition and related to the sympathetic overdrive blood pressure appears to be the most important one, at variance from what described in obesity in which metabolic and anthropometric factors play a major role. Finally in metabolic syndrome HR does not appear to represent a faithful mirror of the occurring sympathetic activation.

Autonomic Cardiovascular Alterations in Chronic Kidney Disease: Effects of Dialysis, Kidney Transplantation, and Renal Denervation

PURPOSE OF REVIEW

To review the results of studies of the effects of dialysis and kidney transplantation on the autonomic nervous system alterations that occur in chronic kidney disease.

RECENT FINDINGS

Vagal control of the heart mediated by arterial baroreceptors is altered early in the course of the renal disease. Sympathetic activation occurs, with increases in resting heart rate, venous plasma norepinephrine levels, muscle sympathetic nerve traffic, and other indirect indices of adrenergic drive. The magnitude of the changes reflects the clinical severity of the kidney disease. Both the sympathetic and parasympathetic alterations have a reflex origin, depending on the impairment in baroreflex and cardiopulmonary reflex control of the cardiovascular system. These alterations are partially reversed during acute hemodialysis, but the responses are variable depending on the specific type of dialytic treatment that is employed. Renal transplantation improves reflex cardiovascular control, resulting in sympathoinhibition following renal transplantation if the native kidneys are removed. Sympathoinhibitory effects have been also reported in renal failure patients after bilateral renal denervation. Assessment of autonomic nervous system responses to dialysis and renal transplantation provides information of clinical interest, given the evidence that autonomic alterations are involved in the development and progression of cardiovascular complications, as well as in the prognosis of chronic kidney disease.

Limited reliability of heart rate as a sympathetic marker in chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is characterized by a pronounced sympathetic overactivity as documented by the marked increase in muscle sympathetic nerve traffic (MSNA) and in plasma norepinephrine reported in this condition. Whether and to what extent in CKD heart rate (HR) reflects the adrenergic overdrive remains undefined. It is also undefined the relative validity of the different adrenergic markers in reflecting renal dysfunction.

MATERIALS AND METHODS

In 82 CKD patients, aged 58.4 ± 1.1 years (mean ± SEM), we measured resting clinic blood pressure, HR (EKG), venous NE (HPLC) and MSNA (microneurography). The same measurements were made in 24 age-matched healthy controls.

RESULTS

HR was significantly greater in CKD than in controls (74.0 ± 1.1 versus 68.2 ± 1.8 bpm, P < 0.02) and significantly directly related to the elevated plasma norepinephrine and MSNA values (r = 0.22 and 0.39, P < 0.05 and <0.0003, respectively). Both MSNA and plasma norepinephrine were significantly and inversely related to the estimated glomerular filtration rate. The correlation did not achieve statistical significance for HR. Similar results were obtained examining the relationships with left ventricular mass index.

CONCLUSION

Our data show that in CKD not only peripheral but also cardiac sympathetic drive is markedly enhanced and HR can be regarded as a marker of the adrenergic overdrive characterizing this condition. The reliability of HR as sympathetic marker appears to be limited, however, this variable being unable to closely reflect, at variance from MSNA and plasma norepinephrine, the interindividual differences in renal dysfunction and the accompanying structural cardiovascular alterations.

Association of Resting Heart Rate With Blood Pressure and Incident Hypertension Over 30 Years in Black and White Adults: The CARDIA Study

Few studies have assessed the association of resting heart rate (RHR) through young adulthood with incident hypertension by middle age. We investigated the association between RHR measured over 30 years with incident hypertension in a cohort of young Black and White men and women. A joint longitudinal time-to-event model consisting of a mixed random effects submodel, quadratic in follow-up time, and a survival submodel adjusted for confounders, was used to determine hazard ratios for a 10 bpm higher RHR. Race-sex specific effects were examined in a single joint model that included interactions of race-sex groups with longitudinal RHR. Out of 5115 participants enrolled in year 0 (1985-1986), after excluding prevalent cases of hypertension at baseline, 1615 men and 2273 women were included in the analytic cohort. Hypertension event rates per 1000 person-years were 42.5 and 25.7 in Black and White men, respectively, and 36.2 and 15.3 in Black and White women, respectively. The hazard ratios for a 10 bpm higher RHR were 1.47 (95% CI, 1.23-1.75), 1.51 (95% CI, 1.28-1.78), 1.48 (95% CI, 1.26-1.73), and 1.02, (95% CI, 0.89-1.17) for Black men, White men, White women, and Black women, respectively. Higher RHR during young adulthood is associated with a greater risk of incident hypertension by middle age. The association is similarly strong in Black men, White men, and White women, but absent in Black women, which may suggest racial differences in the effect of sympathetic nervous activity on hypertension among women.

Sympathetic neural overdrive in congestive heart failure and its correlates: systematic reviews and meta-analysis

BACKGROUND AND OBJECTIVES

Sympathetic neural activation occurs in congestive heart failure (CHF). However, the small sample size of the microneurographic studies, heterogeneity of the patients examined, presence of comorbidities as well as confounders (including treatment) represented major weaknesses not allowing to identify the major features of the phoenomenon, particularly in mild CHF. This meta-analysis evaluated 2530 heart failure (CHF) patients recruited in 106 microneurographic studies. It was based on muscle sympathetic nerve activity (MSNA) quantification in CHF of different clinical severity, but data from less widely addressed conditions, such as ischemic vs. idiopathic, were also considered.

METHODS

Assessment was extended to the relationships of MSNA with venous plasma norepinephrine, heart rate (HR) and echocardiographic parameters of cardiac morphology [left ventricular (LV) end-diastolic diameter] and function (LV ejection fraction) as well.

RESULTS

MSNA was significantly greater (1.9 times, P < 0.001) in CHF patients as compared with healthy controls, a progressive significant increase being observed from New York Heart Association classes I-IV in unadjusted and adjusted analyses. MSNA was significantly greater in both untreated and treated CHF (P < 0.001 for both), related to left ventricular (LV) end-diastolic diameter and to a lesser extent to LV ejection fraction (r = 0.24 and -0.05, P < 0.001 and <0.01, respectively), and closely associated with HR (r = 0.66, P < 0.001) and plasma norepinephrine (r = 0.68, P < 0.001).

CONCLUSION

CHF is characterized by sympathetic overactivity which mirrors the degree of LV dysfunction independently of the stage of CHF, its cause and presence of confounders or pharmacological treatment. plasma norepinephrine and HR represent potentially valuable surrogate markers of sympathetic activation in the clinical setting.

Heart rate as a predictor of cardiovascular risk

Heart rate is a parameter that is very easy to measure and is widely used both in clinic and during daily life activities. Its value gained more relevance with the evidence, in prospective studies and meta-analysis, of association between elevated heart rate values and diseases and outcomes.The increased knowledge of physiological mechanisms of heart rate control and the pathophysiological mechanisms responsible for its dysfunction allows to identify the cut-off value of normalcy providing info for non-pharmacological and pharmacological treatments to reduce the cardiovascular risk both in general population and in pathophysiological conditions. This paper overviews the knowledges of the role of resting heart rate as predictor of cardiovascular risk.

Resting heart rate control and prognosis in coronary artery disease patients with hypertension previously treated with bisoprolol: a sub-group analysis of the BISO-CAD study

BACKGROUND

Resting heart rate (RHR) is considered as a strong predictor of total mortality and hospitalization due to heart failure in hypertension patients. Bisoprolol fumarate, a second-generation beta-adrenoreceptor blockers (β-blocker) is commonly prescribed drug to manage hypertension. The present study was to retrospectively evaluate changes in the average RHR and its association with cardiovascular outcomes in bisoprolol-treated coronary artery disease (CAD) patients from the CAD treated with bisoprolol (BISO-CAD) study who had comorbid hypertension.

METHODS

We performed ad-hoc analysis for hypertension sub-group of the BISO-CAD study (n = 866), which was a phase IV, multination, multi-center, single-arm, observational study carried out from October 2011 to July 2015 across China, South Korea, and Vietnam. Multivariate regression analysis was used to identify factors associated with incidence of composite cardiac clinical outcome (CCCO), the results were presented as adjusted odds ratio (OR) along with 95% confidence interval (CI) and adjusted P value.

RESULTS

A total of 681 patients (mean age: 64.77 ± 10.33 years) with hypertension from BISO-CAD study were included in the analysis. Bisoprolol improved CCCOs in CAD patients with comorbid hypertension, with RHR <65 and <70 beats/min compared with RHR ≥65 and ≥75 beats/min, respectively, in the efficacy analysis (EA) set. In addition, it lowered RHR in both intent-to-treat (ITT) and EA groups after 6, 12, and 18 months of treatment. Further, RHR 70 to 74 beats/min resulted in significantly higher risk of CCCOs EA set of patients (adjusted OR: 4.34; 95% CI: 1.19-15.89; P = 0.03). Also, events of hospitalization due to acute coronary syndrome were higher when RHR 69 to 74 beats/min compared to RHR <69 beats/min in ITT patients.

CONCLUSION

Bisoprolol can effectively reduce RHR in Asian CAD patients with comorbid hypertension and hence, improve CCCO without affecting their blood pressure.

Circadian-timed quick-release bromocriptine lowers elevated resting heart rate in patients with type 2 diabetes mellitus

OBJECTIVE

Sympathetic nervous system (SNS) overactivity is a risk factor for insulin resistance and cardiovascular disease (CVD). We evaluated the impact of bromocriptine-QR, a dopamine-agonist antidiabetes medication, on elevated resting heart rate (RHR) (a marker of SNS overactivity in metabolic syndrome), blood pressure (BP) and the relationship between bromocriptine-QR's effects on RHR and HbA1c in type 2 diabetes subjects.

DESIGN AND SUBJECTS

RHR and BP changes were evaluated in this post hoc analysis of data from a randomized controlled trial in 1014 type 2 diabetes subjects randomized to bromocriptine-QR vs placebo added to standard therapy (diet ± ≤2 oral antidiabetes medications) for 24 weeks without concomitant antihypertensive or antidiabetes medication changes, stratified by baseline RHR (bRHR).

RESULTS

In subjects with bRHR ≥70 beats/min, bromocriptine-QR vs placebo reduced RHR by -3.4 beats/min and reduced BP (baseline 130/79; systolic, diastolic, mean arterial BP reductions [mm Hg]: -3.6 [P = .02], -1.9 [P = .05], -2.5 [P = .02]). RHR reductions increased with higher baseline HbA1c (bHbA1c) (-2.7 [P = .03], -5 [P = .002], -6.1 [P = .002] with bHbA1c ≤7, >7, ≥7.5%, respectively] in the bRHR ≥70 group and more so with bRHR ≥80 (-4.5 [P = .07], -7.8 [P = .015], -9.9 [P = .005]). Subjects with bRHR <70 had no significant change in RHR or BP. With bHbA1c ≥7.5%, %HbA1c reductions with bromocriptine-QR vs placebo were -0.50 (P = .04), -0.73 (P = .005) and -1.22 (P = .008) with bRHR <70, ≥70 and ≥80, respectively. With bRHR ≥70, the magnitude of bromocriptine-QR-induced RHR reduction was an independent predictor of bromocriptine-QR's HbA1c lowering effect.

CONCLUSION

Bromocriptine-QR lowers elevated RHR with concurrent decrease in BP and hyperglycaemia. These findings suggest a potential sympatholytic mechanism contributing to bromocriptine-QR's antidiabetes effect and potentially its previously demonstrated effect to reduce CVD events.