Importance of heart rate in determining beta-blocker efficacy in acute and long-term acute myocardial infarction intervention trials

Cardiac muscle contracts more efficiently at lower contraction frequencies

This study investigated how contraction frequency impacts the mechano-energetics of cardiac muscle performing mechanical work. Left-ventricular trabeculae were isolated from rat hearts and mounted in our work-loop calorimeter to assess their function at physiological temperature (37°C) across three stimulation frequencies, 2 Hz, 3.5 Hz and 5 Hz, in a randomised sequence. Each trabecula was subjected to two experimental protocols: work-loop contractions under a range of afterloads and isometric contractions under a range of muscle lengths. Two contraction protocols allowed the partition of the various components of energy expenditure during cardiac contraction. By simultaneously measuring force-length work and heat output, mechanical efficiency was calculated over a range of afterloads to determine the peak value. Our findings revealed that force production, activation heat (energy associated with Ca2+ cycling) and cross-bridge heat were unaffected by stimulation frequency. Trabeculae produced greater work output per twitch at 2 Hz and 3.5 Hz than at 5 Hz. Positive correlations among work output, shortening extent and mechanical efficiency were detected. From these findings it was concluded that the higher work output at lower frequencies is associated with greater extent of shortening, which correlates to greater mechanical efficiency. This study highlights the mechano-energetic advantage of ventricular trabeculae in terms of increased work output and energy efficiency gained from operating at lower contraction frequencies, supporting the notion that heart rate reduction produces direct benefits on cardiac energetics.

Posttreatment pulse rate reduction and not baseline pulse rate as an indicator of blood pressure response to nebivolol: a subanalysis from the real-world BENEFIT-KOREA study

Background

This subanalysis of BENEFIT-KOREA cohort assessed the impact of baseline pulse rate (PR) and posttreatment PR reduction on the blood pressure (BP)-lowering efficacy of nebivolol in patients with hypertension.

Methods

South Korean patients with hypertension were enrolled in the BENEFIT-KOREA study; 3,011 patients received nebivolol as monotherapy/add-on therapy. Time-averaged BP, calculated by sum of the product of BPs at weeks 12 and 24 corrected for number of participants at these timepoints, was evaluated with/without adjustment for baseline BP. Change in BP in baseline PR groups of < 70, 70-79, and ≥ 80 beats/min and posttreatment PR reduction groups of < 1, 1-9, and ≥ 10 beats/min at 24 weeks were evaluated.

Results

The unadjusted time-averaged systolic BP (SBP) at 24 weeks was not significantly different within baseline PR groups or posttreatment PR reduction groups, but the unadjusted time-averaged diastolic BP (DBP) was significantly different within both baseline PR (P < 0.001) and posttreatment PR reduction groups (P < 0.001). Significant differences were observed in adjusted time-averaged SBP (≥ 10 beats/min group: β, -3.4148; P = 0.006) and time-averaged DBP (≥ 10 beats/min: β, -4.5781; P < 0.001) only within the posttreatment PR reduction groups. The majority of adverse events reported with nebivolol were mild.

Conclusions

The efficacy of nebivolol for BP reduction seems to be indicated not by baseline PR but by posttreatment PR reduction. These findings suggest the presence of other mechanisms in addition to sympathetic inhibition which potentially weaken the relationship between baseline PR and BP reduction.

Trial Registration

ClinicalTrials.gov Identifier: NCT03847350.

Routine beta-blocker therapy after acute coronary syndromes: The end of an era?

BACKGROUND

Beta-blocker therapy, a treatment burdened by side effects including fatigue, erectile dysfunction and depression, was shown to reduce mortality and cardiovascular events after acute coronary syndromes (ACS) in the pre-coronary reperfusion era. Potential mechanisms include protection from ventricular arrhythmias, increased ischaemia threshold and prevention of left ventricular (LV) adverse remodelling. With the advent of early mechanical reperfusion and contemporary pharmacologic secondary prevention, the benefit of beta-blockers after ACS in the absence of LV dysfunction has been challenged.

METHODS

The present narrative review discusses the contemporary evidence based on searching the PubMed database and references in identified articles.

RESULTS

Recently, the REDUCE-AMI trial-the first adequately powered randomized trial in the reperfusion era to test beta-blocker therapy after myocardial infarction with preserved left ventricular ejection fraction (LVEF)-showed no benefit on the composite of all-cause death or myocardial infarction over a median 3.5-year follow-up. While the benefit of beta-blockers in patients with reduced LVEF remains undisputed, their value in post-ACS patients with mildly reduced systolic function (LVEF 41%-49%) has not been studied in contemporary randomized trials; in this setting, observational studies have suggested a reduction in cardiovascular events with these agents. The adequate duration of beta-blocker therapy remains unknown, but observational data suggests that any mortality benefit may be lost beyond 1-12 months after ACS in patients with LVEF >40%.

CONCLUSION

We believe that there is sufficient evidence to abandon routine beta-blocker prescription in post-ACS patients with preserved LV systolic function.

Impact of β-blockers on in-hospital mortality in patients with heart failure: a retrospective propensity-score matched analysis based on MIMIC-IV database

Introduction

This study assessed the relationship between β-blockers treatment and in-hospital mortality among individuals diagnosed with heart failure (HF).

Methods

A retrospective cohort study was carried out on 9,968 HF patients sourced from the Medical Information Mart for Intensive Care (MIMIC)-IV database. Propensity score matching (PSM) was employed to balance the baseline differences. A multivariate regression analysis was utilized to evaluate the impact of β-blockers therapy on in-hospital mortality.

Results

Among the 9,968 patients, 6,439 (64.6%) were β-blockers users. Before matching, the overall in-hospital mortality rate was 12.2% (1,217/9,968). Following PSM, a total of 3,212 patient pairs were successfully matched. The analysis revealed a correlation between β-blockers therapy and decreased in-hospital mortality (odds ratio 0.51 [0.43-0.60], P < 0.001), as well as shorter Los (length of stay) hospital (β -1.43 [-1.96∼-0.09], P < 0.001). Notably, long-acting β-blockers treatment was linked to a decreased risk of in-hospital mortality (odds ratio 0.55 [0.46-0.65], P < 0.001) and a shorter Los hospital (β -1.21 [-1.80∼-0.63], P < 0.001). Conversely, the research results did not show a notable decrease in-hospital mortality (odds ratio 0.66 [0.44-1.01], P = 0.051) or Los hospital (β -1.01 [-2.2∼-0.25], P = 0.117) associated with short-acting β-blocker therapy.

Discussion

β-blockers therapy in the intensive care unit demonstrates potential benefits in lowering the risk of in-hospital mortality and reducing the duration of hospitalization among patients with HF. Specifically, long-acting β-blockers exhibit a protective effect by significantly decreasing both in-hospital mortality and Los hospital. Conversely, the study did not observe a substantial impact on in-hospital mortality or Los hospital duration in this cohort of patients following the administration of short-acting β-blockers.

Personalized accelerated physiologic pacing

Heart failure with preserved ejection fraction (HFpEF) is increasingly prevalent with a high socioeconomic burden. Pharmacological heart rate lowering was recommended to improve ventricular filling in HFpEF. This article discusses the misperceptions that have resulted in an overprescription of beta-blockers, which in all likelihood have untoward effects on patients with HFpEF, even if they have atrial fibrillation or coronary artery disease as a comorbidity. Directly contradicting the lower heart rate paradigm, faster heart rates provide haemodynamic and structural benefits, amongst which lower cardiac filling pressures and improved ventricular capacitance may be most important. Safe delivery of this therapeutic approach is feasible with atrial and ventricular conduction system pacing that aims to emulate or enhance cardiac excitation to maximize the haemodynamic benefits of accelerated pacing. This conceptual framework was first tested in the myPACE randomized controlled trial of patients with pre-existing pacemakers and preclinical or overt HFpEF. This article provides the background and path towards this treatment approach.

Importance of resting heart rate

Resting heart rate is a determinant of cardiac output and physiological homeostasis. Although a simple, but critical, parameter, this vital sign predicts adverse outcomes, including mortality, and development of diseases in otherwise normal and healthy individuals. Temporal changes in heart rate can have valuable predictive capabilities. Heart rate can reflect disease severity in patients with various medical conditions. While heart rate represents a compilation of physiological inputs, including sympathetic and parasympathetic tone, aside from the underlying intrinsic sinus rate, how resting heart rate affects outcomes is uncertain. Mechanisms relating resting heart rate to outcomes may be disease-dependent but why resting heart rate in otherwise healthy, normal individuals affects outcomes remains obscure. For specific conditions, physiologically appropriate heart rate reductions may improve outcomes. However, to date, in the normal population, evidence that interventions aimed at reducing heart rate improves outcomes remains undefined. Emerging data suggest that reduction in heart rate via vagal activation and/or sympathetic inhibition is propitious.

Association between the β-blocker use and patients with sepsis: a cohort study

Objective

This study aimed to assess whether β-blockers are associated with mortality in patients with sepsis.

Method

We conducted a retrospective cohort study of patients with sepsis using the Medical Information Market for Intensive Care (MIMIC)-IV and the emergency intensive care unit (eICU) databases. The primary outcome was the in-hospital mortality rate. The propensity score matching (PSM) method was adopted to reduce confounder bias. Subgroup and sensitivity analyses were performed to test the stability of the conclusions.

Results

We included a total of 61,751 patients with sepsis, with an overall in-hospital mortality rate of 15.3% in MIMIC-IV and 13.6% in eICU. The inverse probability-weighting model showed that in-hospital mortality was significantly lower in the β-blockers group than in the non-β-blockers group [HR = 0.71, 95% CI: 0.66-0.75, p < 0.001 in MIMIC-IV, and HR = 0.48, 95% CI: 0.45-0.52, p < 0.001 in eICU]. In subgroups grouped according to sex, age, heart rate, APSIII, septic shock, and admission years, the results did not change.

Conclusion

β-blocker use is associated with lower in-hospital mortality in patients with sepsis, further randomized trials are required to confirm this association.

Admission Heart Rate and Mortality in Critically Ill Patients with Acute Aortic Dissection

The association between admission heart rate (HR) and the mortality of critically ill patients with acute aortic dissection (AAD) remains unclear.The data were extracted from the Medical Information Mart for Intensive Care (MIMIC-III) database. Cox regression models and Kaplan-Meier (KM) survival curve were used to explore the association between admission HR and 90-day, 1-year, and 3-year mortality in patients with AAD. Sensitivity analyses were conducted to assess potential bias.A total of 374 eligible AAD patients were included and divided in 4 groups according to admission HR (HR ≤ 70, 71-80, 81-90, and > 90 beats per minute (bpm) ). The patients with AAD in the group with HR > 90 bpm had higher 90-day, 1-year, and 3-year mortality than those in the groups with HR ≤ 70, 71-80, and 81-90 bpm. After adjusting for age, sex, BMI, systolic blood pressure, diastolic blood pressure, SOFA score, SAPSII score, Stanford type, hypertension, coronary artery disease, liver disease, atrial fibrillation, valvular disease, intensive care unit mechanical ventilation, aortic surgery, and thoracic endovascular aortic repair, patients with admission HR > 90 bpm had a higher risk of 90-day, 1-year, and 3-year mortality [adjusted hazard ratio, 95% confidence interval, 5.14 (2.22-11.91) P < 0.001; 4.31 (2.10-8.84) P < 0.001; 3.01 (1.66-5.46) P < 0.001] than those with HR 81-90 bpm. The 90-day, 1-year, and 3-year mortality were similar among the groups with HR ≤ 70, 71-80, and 81-90 bpm.Admission HR > 90 bpm was independently associated with all-cause mortality in critically ill AAD patients, either type A or B aortic dissection.

Initial in-hospital heart rate is associated with long-term survival in patients with acute ischemic stroke

Aims

Increased heart rate has been associated with stroke risk and outcomes. The purpose of this study was to explore the long-term prognostic value of initial in-hospital heart rate in patients with acute ischemic stroke (AIS).

Methods

We analyzed data from 21,655 patients with AIS enrolled (January 2010–September 2018) in the Chang Gung Research Database. Mean initial in-hospital heart rates were averaged and categorized into 10-beat-per-minute (bpm) increments. The primary and secondary outcomes were all-cause mortality and cardiovascular death. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariable adjusted Cox proportional hazard models, using the heart rate < 60 bpm subgroup as the reference.

Results

The adjusted HRs for all-cause mortality were 1.23 (95% CI 1.08–1.41) for heart rate 60–69 bpm, 1.74 (95% CI 1.53–1.97) for heart rate 70–79 bpm, 2.16 (95% CI 1.89–2.46) for heart rate 80–89 bpm, and 2.83 (95% CI 2.46–3.25) for heart rate ≥ 90 bpm compared with the reference group. Likewise, heart rate ≥ 60 bpm was also associated with an increased risk of cardiovascular death (adjusted HR 1.18 [95% CI 0.95–1.46] for heart rate 60–69 bpm, 1.57 [95% CI 1.28–1.93] for heart rate 70–79 bpm, 1.98 [95% CI 1.60–2.45] for heart rate 80–89 bpm, and 2.36 [95% CI 1.89–2.95] for heart rate ≥ 90 bpm).

Conclusions

High initial in-hospital heart rate is an independent predictor of all-cause mortality and cardiovascular death in patients with AIS.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00392-021-01953-5.

Heart Rate Predicts the Risk of New-Onset Peripheral Arterial Disease in a Community-Based Population in China

Introduction

Elevated heart rate is linked with poor prognosis and has been shown to accelerate the progress of atherosclerosis. However, the association between heart rate and new-onset PAD is unknown.

Methods

A total of 3463 participants without PAD at baseline from a community-based cohort in Beijing were included and followed up for 2.3 years. PAD was defined as ankle–brachial index (ABI) ≤0.9. We used multivariate logistic regression models to investigate the association of heart rate and the risk of new-onset PAD.

Results

Participants were 56.67 ± 8.54 years old, and 36.12% were men. The baseline ABI was 1.11 ± 0.08, and the incidence of new-onset PAD was 2.97%. Multivariate regression models, adjusted for sex, age, risk factor of atherosclerosis, medications, and baseline ABI, showed that heart rate was significantly associated with incidence of PAD (odds ratio [OR] = 1.22, 95% confidence interval [CI]: 1.03–1.43, P = 0.020); every increase of 10 heart beats per minute (bpm) was associated with a 22% increase in the odds of developing new-onset PAD. Respondents in the higher-heart rate group (≥80 bpm) had an increased risk of new-onset PAD, compared with those in the lower-heart rate group (<80 bpm) (OR = 1.73, 95% CI: 1.14–2.63, P = 0.010). Subgroup analyses revealed no significant heterogeneity among the analyzed subgroups.

Conclusion

Elevated heart rate was independently associated with the risk of new-onset PAD in a community-based population in Beijing. Heart rate management should be considered for the purpose of PAD prevention.

Optimal Dose and Type of β-blockers in Patients With Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

The clinical benefit of β-blockers in modern reperfusion era is not well determined. We investigated the impact of β-blockers in acute coronary syndrome (ACS) after percutaneous coronary intervention. From the Grand-DES registry, a patient-level pooled registry consisting of 5 Korean multicenter prospective drug-eluting stent registries, a total of 6,690 ACS patients were included. Prescription records of dose and type of β-blockers were investigated trimonthly from discharge. Patients were categorized by the mean value of doses during the follow-up (≥50% [high-dose], ≥25% to <50% [medium-dose], and <25% [low-dose] of the full dose that was used in each randomized clinical trial) and vasodilating property of β-blockers. Three-year cumulative risk of all-cause death, cardiac death, and myocardial infarction were assessed. Patients receiving β-blockers were associated with a lower risk of all-cause and cardiac death compared with those not receiving β-blockers (adjusted hazard ratio [aHR] 0.29, 95% confidence interval [CI] 0.24 to 0.35 for all-cause death; aHR 0.27, 95% CI 0.21 to 0.34 for cardiac death). Medium-dose β-blocker group was associated with a lower risk of cardiac death compared with high- and low-dose β-blocker groups (aHR 0.49, 95% CI 0.25 to 0.96, for high-dose; aHR 0.46, 95% CI 0.29 to 0.74, for low-dose). Patients receiving vasodilating β-blockers were associated with a lower risk of cardiac death compared with those receiving conventional β-blockers (aHR 0.58, 95% CI 0.40 to 0.84). In conclusion, β-blocker therapy was associated with better clinical outcomes in patients with ACS, especially with medium-dose and vasodilating β-blockers.

Ivabradine is as effective as metoprolol in the prevention of ventricular arrhythmias in acute non-reperfused myocardial infarction in the rat

Ventricular arrhythmias are a major source of early mortality in acute myocardial infarction (MI) and remain a major therapeutic challenge. Thus we investigated effects of ivabradine, a presumably specific bradycardic agent versus metoprolol, a β-blocker, at doses offering the same heart rate (HR) reduction, on ventricular arrhythmias in the acute non-reperfused MI in the rat. Immediately after MI induction a single dose of ivabradine/ metoprolol was given. ECG was continuously recorded and ventricular arrhythmias were analyzed. After 6 h epicardial monophasic action potentials (MAPs) were recorded and cardiomyocyte Ca²⁺ handling was assessed. Both ivabradine and metoprolol reduced HR by 17% and arrhythmic mortality (14% and 19%, respectively, versus 33% in MI, p < 0.05) and ventricular arrhythmias in post-MI rats. Both drugs reduced QTc prolongation and decreased sensitivity of ryanodine receptors in isolated cardiomyocytes, but otherwise had no effect on Ca²⁺ handling, velocity of conduction or repolarization. We did not find any effects of potential I_Kr inhibition by ivabradine in this setting. Thus Ivabradine is an equally effective antiarrhythmic agent as metoprolol in early MI in the rat. It could be potentially tested as an alternative antiarrhythmic agent in acute MI when β-blockers are contraindicated.

Differential Effect of β-Blockers According to Heart Rate in Acute Myocardial Infarction Without Heart Failure or Left Ventricular Systolic Dysfunction: A Cohort Study

OBJECTIVE

To evaluate the effect of β-blockers according to heart rate in patients with acute myocardial infarction (AMI) without heart failure (HF) or left ventricular systolic dysfunction (LVSD).

PATIENTS AND METHODS

We enrolled patients with AMI without HF or LVSD between June 1, 2003, and February 28, 2015, from Seoul National University Hospital Acute Myocardial Infarction Registry. Patients were categorized according to discharge heart rate recorded on electrocardiographs and β-blocker use. Low heart rate was defined as less than 75 beats/min. The primary end point was 5-year all-cause mortality according to discharge heart rate and β-blocker use.

RESULTS

Of 2271 patients, 1696 (74.7%) received β-blockers and 1427 (62.8%) had low heart rates. At 5 years after discharge, 205 patients died. Overall, patients with low heart rates (P<.001) and those with β-blocker treatment had lower mortality (P<.001). After adjustment for covariates, β-blocker use was associated with 48% reduced risk for 5-year mortality in patients with high heart rates (hazard ratio, 0.52; 95% CI, 0.35-0.76), but not in those with low heart rates (P=.97). In an inverse-probability treatment-weighted cohort, β-blocker use was also associated with improved mortality in those with a high heart rate. Findings were similar for 5-year cardiovascular mortality.

CONCLUSION

Among survivors with AMI without HF or LVSD, β-blocker use was associated with reduced 5-year all-cause mortality in patients who have high heart rates, but not in those with low heart rates.

Ivabradine Improves Cardiac Function and Increases Exercise Capacity in Patients with Chronic Heart Failure

To systematically review and conduct a meta-analysis of the ivabradine-induced improvement in cardiopulmonary function, exercise capacity, and primary composite endpoints in patients with chronic heart failure (CHF).This study was a systematic review and meta-analysis.Databases, including PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Clinical Trials and European Union Clinical Trials, were searched for randomized placebo-controlled trials. The efficacy and safety of ivabradine treatment in patients with CHF were assessed and compared to those of the standard anti-heart failure treatment. Review Manager 5.3 software was used to analyze the relative risk (RR) for dichotomous data and the mean difference (MD) for continuous data.In total, 22 studies with 24,562 patients were included. Cardiopulmonary function analysis showed that treatment with added ivabradine reduced the heart rate (MD = -17.30, 95% confidence interval (CI): 19.52--15.08, P < 0.00001), significantly increased the left ventricular ejection fraction (LVEF) (MD = 3.90, 95% CI: 0.40-7.40, P < 0.0001), and led to a better New York Heart Association (NYHA) classification. Ivabradine significantly reduced the minute ventilation/carbon dioxide production (VE/VCO₂) (MD = -2.68, 95% CI: -4.81--0.55, P = 0.01) and improved the peak VO₂ (MD = 2.80, 95% CI: 1.05-4.55, P = 0.002) and the exercise capacity, including the exercise duration with a submaximal load (MD = 7.82, 95% CI: -2.57--18.21, P < 0.00001) and the 6-minute walk distance. The RR of cardiovascular death or worsening heart failure was significantly decreased (RR = 0.93, 95% CI: 0.87--0.98, P = 0.01) in the patients treated with ivabradine. Additionally, the RRs of heart failure and hospitalization also decreased (RR = 0.91, 95% CI: 0.85--0.97, P = 0.006; RR = 0.86, 95% CI: 0.79--0.93, P = 0.0002). Safety analysis showed no significant difference in the RR of severe adverse events between the ivabradine group and the standard anti-heart failure treatment group (P = 0.40). However, ivabradine significantly increased the RR of visual symptoms in CHF patients (RR = 3.82, 95% CI: 1.80--8.13, P = 0.0005).Existing evidence showed that adding ivabradine treatment significantly improved the cardiopulmonary function and increased the exercise capacity of patients with CHF. Adding ivabradine to the standard anti-heart failure treatment reduced the mortality and hospitalization risk and improved the quality of life. Finally, ivabradine significantly increased the RR of visual symptoms in CHF patients.This is the first systematic review and meta-analysis to focus on the efficacy of ivabradine, which improved the cardiac function and increased the exercise capacity in patients with chronic heart failure (CHF). Therefore, this study will help evaluate the quality of life after adding ivabradine to the treatment of patients with CHF, even though there are differences in the standard for resting heart rate, left ventricular ejection fraction (LVEF), and New York Heart Association (NYHA) class in the included studies. This hybrid effect might be smaller when analyzed separately but might have a higher heterogeneity when analyzed in multiple studies.

The Impact of Hemodynamic Reflex Compensation Following Myocardial Infarction on Subsequent Ventricular Remodeling

Patients who survive a myocardial infarction (MI) are at risk for ventricular dilation and heart failure. While infarct size is an important determinant of post-MI remodeling, different patients with the same size infarct often display different levels of left ventricular (LV) dilation. The acute physiologic response to MI involves reflex compensation, whereby increases in heart rate, arterial resistance, venoconstriction, and contractility of the surviving myocardium act to maintain mean arterial pressure. We hypothesized that variability in compensation might underlie some of the reported variability in post-MI remodeling, a hypothesis that is difficult to test using experimental data alone because some responses are difficult or impossible to measure directly. We therefore employed a computational model to estimate the balance of compensatory mechanisms from experimentally reported hemodynamic data. We found a strikingly wide range of compensatory reflex profiles in response to MI in dogs and verified that pharmacologic blockade of sympathetic and parasympathetic reflexes nearly abolished this variability. Then, using a previously published model of post-infarction remodeling, we showed that observed variability in compensation translated to variability in predicted LV dilation consistent with published data. Treatment with a vasodilator shifted the compensatory response away from arterial and venous vasoconstriction and towards increased heart rate and myocardial contractility. Importantly, this shift reduced predicted dilation, a prediction that matched prior experimental studies. Thus, post-infarction reflex compensation could represent both a source of individual variability in the extent of LV remodeling and a target for therapies aimed at reducing that remodeling.

Admission Heart Rate Is a Determinant of Effectiveness of Beta-Blockers in Acute Myocardial Infarction Patients

BACKGROUND

Beta-blockers are standard therapy for acute myocardial infarction (AMI). However, despite current advances in the management of AMI, it remains unclear whether all AMI patients benefit from β-blockers. We investigated whether admission heart rate (HR) is a determinant of the effectiveness of β-blockers for AMI patients.

METHODS AND RESULTS

We enrolled 3,283 consecutive AMI patients who were admitted to 28 participating institutions in the Japanese Registry of Acute Myocardial Infarction Diagnosed by Universal Definition (J-MINUET) study. According to admission HR, we divided patients into 3 groups: bradycardia (HR <60 beats/min, n=444), normocardia (HR 60 to ≤100 beats/min, n=2,013), and tachycardia (HR >100 beats/min, n=342). The primary endpoint was major adverse cardiac events (MACE), including all-cause death, non-fatal MI, non-fatal stroke, heart failure (HF), and urgent revascularization for unstable angina, at 3-year follow-up. Beta-blocker at discharge was significantly associated with a lower risk of MACE in the tachycardia group (23.6% vs. 33.0%; P=0.033), but it did not affect rates of MACE in the normocardia group (17.8% vs. 18.4%; P=0.681). In the bradycardia group, β-blocker use at discharge was significantly associated with a higher risk of MACE (21.6% vs. 12.7%; P=0.026). Results were consistent for multivariable regression and stepwise multivariable regression.

CONCLUSIONS

Admission HR might determine the efficacy of β-blockers for current AMI patients.

Resting heart rate and relation to disease and longevity: past, present and future

Assessment of heart rate has been used for millennia as a marker of health. Several studies have indicated that low resting heart rate (RHR) is associated with health and longevity, and conversely, a high resting heart to be associated with disease and adverse events. Longitudinal studies have shown a clear association between increase in heart rate over time and adverse events. RHR is a fundamental clinical characteristic and several trials have assessed the effectiveness of heart rate lowering medication, for instance beta-blockers and selective sinus node inhibition. Advances in technology have provided new insights into genetic factors related to RHR as well as insights into whether elevated RHR is a risk factor or risk marker. Recent animal research has suggested that heart rate lowering with sinus node inhibition is associated with increased lifespan. Furthermore, genome-wide association studies in the general population using Mendelian randomization have demonstrated a causal link between heart rate at rest and longevity. Furthermore, the development in personal digital devices such as mobile phones, fitness trackers and eHealth applications has made heart rate information and knowledge in this field as important as ever for the public as well as the clinicians. It should therefore be expected that clinicians and health care providers will be met by relevant questions and need of advice regarding heart rate information from patients and the public. The present review provides an overview of the current knowledge in the field of heart rate and health.

Pharmacological heart rate lowering in patients with a preserved ejection fraction-review of a failing concept

Epidemiological studies have demonstrated that high resting heart rates are associated with increased mortality. Clinical studies in patients with heart failure and reduced ejection fraction have shown that heart rate lowering with beta-blockers and ivabradine improves survival. It is therefore often assumed that heart rate lowering is beneficial in other patients as well. Here, we critically appraise the effects of pharmacological heart rate lowering in patients with both normal and reduced ejection fraction with an emphasis on the effects of pharmacological heart rate lowering in hypertension and heart failure. Emerging evidence from recent clinical trials and meta-analyses suggest that pharmacological heart rate lowering is not beneficial in patients with a normal or preserved ejection fraction. This has just begun to be reflected in some but not all guideline recommendations. The detrimental effects of pharmacological heart rate lowering are due to an increase in central blood pressures, higher left ventricular systolic and diastolic pressures, and increased ventricular wall stress. Therefore, we propose that heart rate lowering per se reproduces the hemodynamic effects of diastolic dysfunction and imposes an increased arterial load on the left ventricle, which combine to increase the risk of heart failure and atrial fibrillation. Pharmacologic heart rate lowering is clearly beneficial in patients with a dilated cardiomyopathy but not in patients with normal chamber dimensions and normal systolic function. These conflicting effects can be explained based on a model that considers the hemodynamic and ventricular structural effects of heart rate changes.

Effect of β-Blockers Beyond 3 Years After Acute Myocardial Infarction

Background

The optimal duration of β‐blocker therapy in patients with acute myocardial infarction (AMI) is unknown. We aimed to evaluate the late effect of β‐blockers in patients with AMI.

Methods and Results

We enrolled all consecutive patients who presented with AMI at Seoul National University Bundang Hospital, between June 3, 2003 and February 24, 2015. The primary end point was 5‐year all‐cause mortality, depending on the use of β‐blockers at discharge, 1 year after AMI, and 3 years after AMI. Of 2592 patients, the prescription rates of β‐blockers were 72%, 69%, 63%, and 60% at discharge and 1, 3, and 5 years after AMI, respectively. The patients who were receiving β‐blocker therapy had more favorable clinical characteristics, such as younger age (62 versus 65 years; P<0.001). They received reperfusion therapy more often (92% versus 80%; P<0.001) than those without β‐blocker prescription. In the univariate analysis, the patients with β‐blocker prescription had lower 5‐year mortality at all time points. In the Cox model after adjustment for significant covariates, β‐blocker prescription at discharge was associated with a 29% reduced mortality risk (hazard ratio, 0.71; 95% confidence interval, 0.55–0.90; P=0.006); however, β‐blocker prescriptions at 1 and 3 years after AMI were not associated with reduced mortality.

Conclusions

The beneficial effect of β‐blocker therapy after AMI may be limited until 1 year after AMI. Whether late β‐blocker therapy beyond 1 year after AMI offers clinical benefits should be confirmed in further clinical trials.

The Role of Ivabradine in the Management of Angina Pectoris

Stable angina pectoris affects 2–4 % of the population in Western countries and entails an annual risk of death and nonfatal myocardial infarction of 1–2 % and 3 %, respectively. Heart rate (HR) is linearly related to myocardial oxygen consumption and coronary blood flow, both at rest and during stress. HR reduction is a key target for the prevention of ischemia/angina and is an important mechanism of action of drugs which are recommended as first line therapy for the treatment of angina in clinical guidelines. However, many patients are often unable to tolerate the doses of beta blocker or non-dihydropyridine calcium antagonists required to achieve the desired symptom control. The selective pacemaker current inhibitor ivabradine was developed as a drug for the management of patients with angina pectoris, through its ability to reduce HR specifically. The available data suggest that ivabradine is a well-tolerated and effective anti-anginal agent and it is recommended as a second-line agent for relief of angina in guidelines. However, recent clinical trials of ivabradine have failed to show prognostic benefit and have raised potential concerns about safety. This article will review the available evidence base for the current role of ivabradine in the management of patients with symptomatic angina pectoris in the context of stable coronary artery disease.

β-blocker dosage and outcomes after acute coronary syndrome

BACKGROUND

Although β-blockers increase survival in acute coronary syndrome (ACS) patients, the doses used in trials were higher than doses used in practice, and recent data do not support an advantage of higher doses. We hypothesized that rates of major adverse cardiac events (MACE), all-cause death, myocardial infarction, and stroke are equivalent for patients on low-dose and high-dose β-blocker.

METHODS

Patients admitted to Intermountain Healthcare with ACS and diagnosed with ≥70% coronary stenosis between 1994 and 2013 were studied (N = 7,834). We classified low dose as ≤25% and high dose as ≥50% of an equivalent daily dose of 200 mg of metoprolol. Multivariate analyses were used to test association between low-dose versus high-dose β-blocker dosage and MACE at 0-6 months and 6-24 months.

RESULTS

A total of 5,287 ACS subjects were discharged on β-blockers (87% low dose, 12% high dose, and 1% intermediate dose). The 6-month MACE outcomes rates for the β-blocker dosage (low versus high) were not equivalent (P = .18) (hazard ratio [HR] = 0.76; 95% CI, 0.52-1.10). However, subjects on low-dose β-blocker therapy did have a significantly decreased risk of myocardial infarction for 0-6 months (HR = 0.53; 95% CI, 0.33-0.86). The rates of MACE events during the 6-24 months after presentation with ACS were equivalent for the 2 doses (P = .009; HR = 1.03 [95% CI, 0.70-1.50]).

CONCLUSIONS

In ACS patients, rates of MACE for high-dose and low-dose β-blocker doses are similar. These findings question the importance of achieving a high dose of β-blocker in ACS patients and highlight the need for further investigation of this clinical question.

Relationships among achieved heart rate, β-blocker dose and long-term outcomes in patients with heart failure with atrial fibrillation

Objective

Higher β-blocker dose and lower heart rate are associated with decreased mortality in patients with systolic heart failure (HF) and sinus rhythm. However, in the 30% of patients with HF with atrial fibrillation (AF), whether β-blocker dose or heart rate predict mortality is less clear. We assessed the association between β-blocker dose, heart rate and all-cause mortality in patients with HF and AF.

Methods

We performed a retrospective cohort study in 935 patients (60% men, mean age 74, 44.7% with reduced left ventricular ejection fraction (LVEF)) discharged with concurrent diagnoses of HF and AF. We used Cox models to test independent associations between higher versus lower predischarge heart rate (dichotomised at 70/min) and higher versus lower β-blocker dose (dichotomised at 50% of the evidence-based target), with the primary composite end point of mortality or cardiovascular rehospitalisation over a median of 2.9 years. All analyses were stratified by the presence of left ventricular systolic dysfunction (LVEF≤40%).

Results

After adjustment for covariates, neither β-blocker dose nor predischarge heart rate was associated with the primary composite end point. However, tachycardia at admission (heart rate >120/min) was associated with a reduced risk of the composite outcome in patients with both reduced LVEF (adjusted HR 0.67, 95% CI 0.52 to 0.88, p<0.01) and preserved LVEF (adjusted HR 0.79, 95% CI 0.64 to 0.98, p=0.04).

Conclusions

We found no associations between predischarge heart rate or β-blocker dosage and clinical outcomes in patients with recent hospitalisations for HF and AF.

β-Adrenergic Blockers as Antiarrhythmic and Antifibrillatory Compounds: An Overview

β-Adrenergic blockers have a wide spectrum of action for controlling cardiac arrhythmias that is larger than initially thought. Data from the past several decades indicate that, as an antiarrhythmic class, β-blockers remain among the very few pharmacologic agents that reduce the incidence of sudden cardiac death, prolong survival, and ameliorate symptoms caused by arrhythmias in patients with cardiac disease. As a class of compounds, β-blockers have a fundamental pharmacologic property that attenuates the effects of competitive adrenergic receptors. However, the net clinical effects of the different β-receptor blockers may vary quantitatively because of variations in associated intrinsic sympathomimetic agonism and in their intrinsic potency for binding to β-receptors. These individual compounds also differ in their selectivity for β1- and β2-receptors. Metoprolol is a β1-selective blocker, whereas carvedilol is a nonselective β1- and β2-blocker, an antioxidant, and has a propensity to inhibit α1-receptors and endothelin. Evolving data from controlled and uncontrolled clinical trials suggest that there are clinically significant differences among this class of drugs. Recent evidence also suggests that the antiarrhythmic actions of certain β-receptor blockers such as carvedilol and metoprolol extend beyond the ventricular tissue to encompass atrial cells and help maintain sinus rhythm in patients with atrial fibrillation, especially in combination with potent antifibrillatory agents such as amiodarone. This introduction provides a current perspective on these newer developments in the understanding of the antiarrhythmic and antifibrillatory actions of β-blockers.

[National disease management guidelines (NVL) for chronic CAD : What is new, what is particularly important?]

Coronary heart disease (CAD) is widespread and affects 1 in 10 of the population in the age group 40-79 years in Germany. The German national management guidelines on chronic CAD comprise evidence and expert-based recommendations for the diagnostics of chronic stable CAD as well as for interdisciplinary/multidisciplinary therapy and care of patients with stable CAD. The focus is on the diagnostics, prevention, medication therapy, revascularization, rehabilitation, general practitioner care and coordination of care. Recommendations for optimizing cooperation between all medical specialties involved as well as the definition of mandatory and appropriate measures are essential aims of the guidelines both to improve the quality of care and to strengthen the position of the patient.

Selective Heart Rate Reduction With Ivabradine Increases Central Blood Pressure in Stable Coronary Artery Disease

Abstract—

Heart rate (HR) lowering by β-blockade was shown to be beneficial after myocardial infarction. In contrast, HR lowering with ivabradine was found to confer no benefits in 2 prospective randomized trials in patients with coronary artery disease. We hypothesized that this inefficacy could be in part related to ivabradine’s effect on central (aortic) pressure. Our study included 46 patients with chronic stable coronary artery disease who were randomly allocated to placebo (n=23) or ivabradine (n=23) in a single-blinded fashion for 6 months. Concomitant baseline medication was continued unchanged throughout the study except for β-blockers, which were stopped during the study period. Central blood pressure and stroke volume were measured directly by left heart catheterization at baseline and after 6 months. For the determination of resting HR at baseline and at follow-up, 24-hour ECG monitoring was performed. Patients on ivabradine showed an increase of 11 mm Hg in central systolic pressure from 129±22 mm Hg to 140±26 mm Hg ( P =0.02) and in stroke volume by 86±21.8 to 107.2±30.0 mL ( P =0.002). In the placebo group, central systolic pressure and stroke volume remained unchanged. Estimates of myocardial oxygen consumption (HR×systolic pressure and time-tension index) remained unchanged with ivabradine.The decrease in HR from baseline to follow-up correlated with the concomitant increase in central systolic pressure ( r =−0.41, P =0.009) and in stroke volume ( r =−0.61, P <0.001). In conclusion, the decrease in HR with ivabradine was associated with an increase in central systolic pressure, which may have antagonized possible benefits of HR lowering in coronary artery disease patients.

Clinical Trials—URL:

http://www.clinicaltrials.gov . Unique identifier NCT01039389.

Heart rate reduction with ivabradine promotes shear stress-dependent anti-inflammatory mechanisms in arteries

Blood flow generates wall shear stress (WSS) which alters endothelial cell (EC) function. Low WSS promotes vascular inflammation and atherosclerosis whereas high uniform WSS is protective. Ivabradine decreases heart rate leading to altered haemodynamics. Besides its cardio-protective effects, ivabradine protects arteries from inflammation and atherosclerosis via unknown mechanisms. We hypothesised that ivabradine protects arteries by increasing WSS to reduce vascular inflammation. Hypercholesterolaemic mice were treated with ivabradine for seven weeks in drinking water or remained untreated as a control. En face immunostaining demonstrated that treatment with ivabradine reduced the expression of pro-inflammatory VCAM-1 (p<0.01) and enhanced the expression of anti-inflammatory eNOS (p<0.01) at the inner curvature of the aorta. We concluded that ivabradine alters EC physiology indirectly via modulation of flow because treatment with ivabradine had no effect in ligated carotid arteries in vivo, and did not influence the basal or TNFα-induced expression of inflammatory (VCAM-1, MCP-1) or protective (eNOS, HMOX1, KLF2, KLF4) genes in cultured EC. We therefore considered whether ivabradine can alter WSS which is a regulator of EC inflammatory activation. Computational fluid dynamics demonstrated that ivabradine treatment reduced heart rate by 20 % and enhanced WSS in the aorta. In conclusion, ivabradine treatment altered haemodynamics in the murine aorta by increasing the magnitude of shear stress. This was accompanied by induction of eNOS and suppression of VCAM-1, whereas ivabradine did not alter EC that could not respond to flow. Thus ivabradine protects arteries by altering local mechanical conditions to trigger an anti-inflammatory response.

Effect of Beta-Blocker Dose on Survival After Acute Myocardial Infarction

BACKGROUND

Beta-blocker therapy after acute myocardial infarction (MI) improves survival. Beta-blocker doses used in clinical practice are often substantially lower than those used in the randomized trials establishing their efficacy.

OBJECTIVES

This study evaluated the association of beta-blocker dose with survival after acute MI, hypothesizing that higher dose beta-blocker therapy will be associated with increased survival.

METHODS

A multicenter registry enrolled 7,057 consecutive patients with acute MI. Discharge beta-blocker dose was indexed to the target beta-blocker doses used in randomized clinical trials, grouped as >0% to 12.5%, >12.5% to 25%, >25% to 50%, and >50% of target dose. Follow-up vital status was assessed, with the primary endpoint of time-to-death right-censored at 2 years. Multivariable and propensity score analyses were used to account for group differences.

RESULTS

Of 6,682 patients with follow-up (median 2.1 years), 91.5% were discharged on a beta-blocker (mean dose 38.1% of the target dose). Lower mortality was observed with all beta-blocker doses (p < 0.0002) versus no beta-blocker therapy. After multivariable adjustment, hazard ratios for 2-year mortality compared with the >50% dose were 0.862 (95% confidence interval [CI]: 0.677 to 1.098), 0.799 (95% CI: 0.635 to 1.005), and 0.963 (95% CI: 0.765 to 1.213) for the >0% to 12.5%, >12.5% to 25%, and >25% to 50% of target dose groups, respectively. Multivariable analysis with an extended set of covariates and propensity score analysis also demonstrated that higher doses were not associated with better outcome.

CONCLUSIONS

These data do not demonstrate increased survival in patients treated with beta-blocker doses approximating those used in previous randomized clinical trials compared with lower doses. These findings provide the rationale to re-engage in research to establish appropriate beta-blocker dosing after MI to derive optimal benefit from this therapy. (The PACE-MI Registry Study-Outcomes of Beta-blocker Therapy After Myocardial Infarction [OBTAIN]: NCT00430612).

Systematic review of use of β-blockers in sepsis

Background and Aims:

We proposed a review of present literature and systematic analysis of present literature to summarize the evidence on the use of β-blockers on the outcome of a patient with severe sepsis and septic shock.

Material and Methods:

Medline, EMBASE, Cochrane Library were searched from 1946 to December 2013. The bibliography of all relevant articles was hand searched. Full-text search of the grey literature was done through the medical institution database. The database search identified a total of 1241 possible studies. The citation list was hand searched by both the authors. A total of 9 studies were identified.

Results:

Most studies found a benefit from β-blocker administration in sepsis. This included improved heart rate (HR) control, decreased mortality and improvement in acid-base parameters. Chronic β-blocker usage in sepsis was also associated with improved mortality. The administration of β-blockers during sepsis was associated with better control of HR. The methodological quality of all the included studies, however, was poor.

Conclusion:

There is insufficient evidence to justify the routine use of β-blockers in sepsis. A large adequately powered multi-centered randomized controlled clinical trial is required to address the question on the efficacy of β-blocker usage in sepsis. This trial should also consider a number of important questions including the choice of β-blocker used, optimal dosing, timing of intervention, duration of intervention and discontinuation of the drug. Until such time based on the available evidence, there is no place for the use of β-blockers in sepsis in current clinical practice.

Resting heart rate associates with one-year risk of major adverse cardiovascular events in patients with acute coronary syndrome after percutaneous coronary intervention

The study was to access the association between resting heart rate (RHR) and one-year risk of major adverse cardiovascular events (MACE) in acute coronary syndrome (ACS) patients after percutaneous coronary intervention (PCI). Patients with ACS after PCI (n = 808) were prospectively followed-up for MACE. RHR was obtained from electrocardiogram. MACE was defined as a composite of cardiac death, nonfatal recurrent myocardial infarction, ischemic-driven revascularization, and ischemic stroke. The association between RHR and one-year risk of MACE was assessed using Cox proportional hazards regression model. Compared with patients with RHR >76 bpm, the adjusted hazard ratio (AHR) was 0.51 (95% confidence intervals [CI]: 0.23-1.14; P = 0.100) for patients with RHR < 61 bpm, and 0.44 (95%CI: 0.23-0.85; P = 0.014) for those with RHR 61-76 bpm. For patients with RHR ≥ 61 bpm, an increase of 10 bpm in RHR was associated with an increase by 38.0% in the risk of MACE (AHR: 1.38; 95% CI: 1.04-1.83; P = 0.026). ACS patients after PCI with RHR >76 bpm were at higher risk of MACE during one-year follow-up compared with patients with RHR 61-76 bpm. An elevated RHR ≥ 61 bpm was associated with increased risk of one-year MACE in ACS patients.

Heart rate and use of β-blockers in Mexican stable outpatients with coronary artery disease

OBJECTIVE

To evaluate the use of β-blockers and to monitor heart rate in Mexican patients with coronary artery disease.

METHODS

CLARIFY is an outpatients registry with stable CAD. A total of 33,283 patients from 45 countries were enrolled between November 2009 and July 2010 from which 1342 were Mexican patients.

RESULTS

The mean HR pulse was 70 bpm (beats per minute). Patients in Mexico were compared with the remaining global CLARIFY population. Patients in Mexico had a higher incidence of acute myocardial infarction and percutaneous coronary intervention, and lower incidence of revascularization surgery compared with the remaining CLARIFY population. More often, Mexican patients presented with diabetes, but less often hypertension and stroke. These patients were split into three mutually exclusive groups of HR ≤ 60 (N=263), HR 61-69 (N=356) and HR ≥ 70 (N=722). Patients with elevated HR had a higher incidence of diabetes and higher diastolic blood pressure on average than those with controlled HR. Regarding the use of β-blockers, they were used in 63.3% of patients, 2.7% showed intolerance or contraindication to treatment to monitor heart rate, and ivabradine was used in 2.3%. Out of approximately 849 patients receiving treatment of β-blockers, 52.1% had ≥ 70 bpm HR.

CONCLUSIONS

In a large proportion of Mexican patients with stable coronary disease the HR remain elevated, > 70 bpm, even with the use of β-blockers; this requires further attention.

The Role of Ivabradine in Cardiac Rehabilitation in Patients With Recent Coronary Artery Bypass Graft

BACKGROUND

Little is known about ivabradine in cardiac rehabilitation in patients with coronary artery bypass graft (CABG).

METHODS

In this prospective, randomized study, suitable patients admitted for cardiac rehabilitation after recent CABG were randomized to ivabradine 5 mg twice a day + standard medical therapy including bisoprolol 1.25 mg once daily (group I-BB, n = 38) or standard medical therapy including bisoprolol 2.5 to 3.75 mg once daily (group BB, n = 43). Patients were evaluated at admission, discharge, and 3 months. The primary end point was improvement in functional status, and other end points were improvement in diastolic function and recovery of systolic function. End points were assessed by distance covered in 6-minute walking test (6MWT), percentage with normal diastolic function, and percentage increase in left ventricular ejection fraction (LVEF).

RESULTS

Cardiac rehabilitation improved functional capacity in both groups. In group BB, distances covered in the 6MWT at admission, discharge, and 3 months were 215 ± 53, 314 ± 32, and 347 ± 42 m, respectively. Corresponding distances in group I-BB were 180 ± 91, 311 ± 58, and 370 ± 55 m. Normal diastolic function was restored in I-BB patients, increasing from 24% at admission to 50% and 79% at discharge and 3 months; in BB patients, it decreased from 23% to 19% and 16%. The LVEF improved in I-BB patients, from 57% ± 3% at admission to 62% ± 4% at discharge and 66% ± 3% at 3 months, while remaining unchanged in BB patients (57% ± 3%, 59% ± 4%, and 59% ± 3%).

CONCLUSION

Adding ivabradine to low-dose bisoprolol during cardiac rehabilitation in patients with CABG improved functional capacity, enhanced recovery of systolic function, and reduced diastolic dysfunction.

Clinic and ambulatory heart rates in patients with ischaemic heart disease and/or chronic heart failure taking rate-limiting medications: are they interchangeable?

BACKGROUND

The prognostic benefit from heart rate (HR) reduction in patients with ischaemic heart disease (IHD) and/or chronic heart failure (CHF) is now firmly established. Most decisions regarding initiation and/or dose adjustment of HR-limiting medications in such patients are based on clinic HR. Yet, this is a highly variable parameter that may not necessarily reflect HR control over the 24 h period.

OBJECTIVE

To examine the level of agreement between mean clinic and mean ambulatory HRs in patients with IHD and/or CHF taking rate-limiting medications.

METHODS

Prospective, observational study. Fifty patients with IHD and/or CHF who attended cardiology outpatient clinics at the Manchester Heart Centre and underwent same-day 24 h continuous ECG recording between March and October 2013 were included in the study. Mean clinic HR was compared with mean 24 h, daytime and night-time HRs. Limits-of-agreement plots were constructed to examine the relationship between the two HR measures in more detail.

RESULTS

The mean clinic HR was numerically similar to the mean HRs of all ambulatory time periods examined. However, on Bland-Altman plots, the limits of agreement between clinic and ambulatory HR means were quite wide, with the mean clinic HR ranging between 10.93 and 13.58 bpm below and 8.4 and 18.15 bpm above the mean ambulatory HR.

CONCLUSIONS

Although numerically similar, the means of clinic and ambulatory HRs in patients with IHD and/or CHF display wide limits of agreement. As such, the two measures cannot be regarded as interchangeable.

Effects of estrogen therapy and aerobic training on sympathetic activity and hemodynamics in healthy postmenopausal women: a double-blind randomized trial

OBJECTIVE

The aim of this study was to evaluate the isolated and associated effects of aerobic training and estrogen therapy on sympathetic nerve activity and hemodynamics in healthy postmenopausal women.

METHODS

Forty-five postmenopausal women (mean [SD] age, 51 [3] y) were randomly divided into four groups: sedentary-placebo (SED-PLA; n = 11), sedentary-estrogen therapy (SED-ET; n = 14), aerobic training-placebo (AT-PLA; n = 12), and aerobic training-estrogen therapy (AT-ET; n = 8). The ET groups received oral estradiol valerate (1 mg/d), whereas the PLA groups received placebo. The AT groups performed aerobic exercise three times a week on a cycle ergometer for 50 minutes, whereas the SED groups remained sedentary. All participants were evaluated before and after 6 months. Muscle sympathetic nerve activity (MSNA; microneurography), forearm blood flow (plethysmography), blood pressure (oscillometry), and heart rate (HR) were measured at rest for 10 minutes. Data were analyzed by three-way analysis of variance.

RESULTS

Estrogen administration itself did not change any of the studied parameters. AT improved forearm blood flow (AT-PLA, 2.02 [0.85] vs 2.92 [1.65] mL min(-1) 100 mL(-1), P = 0.03; AT-ET, 1.68 [1.11] vs 2.27 [0.76] mL min(-1) 100 mL(-1), P = 0.03), reduced MSNA in the AT-PLA group (39 [6] vs 34 [5] bursts/min(-1), P = 0.01), and decreased HR in the AT-ET group (65 [8] vs 62 [7] beats/min, P = 0.01).

CONCLUSIONS

AT reduces sympathetic nerve activity and improves muscle blood flow in healthy hysterectomized postmenopausal women. Moreover, AT decreases HR when combined with ET. However, ET abolishes the reducing effect of AT on MSNA.

β-blockers in postoperative myocardial diastolic dysfunction: not a panacea

Successful treatment with heart rate lowering medication has been used to treat adults with chronic myocardial dysfunction of various aetiologies for a number of years. There has been recent evidence for the successful use of β-receptor blocking medication in highly selected group of infants with diastolic myocardial dysfunction. This case series demonstrates that while the use of β-receptor blockers in infants early following initial treatment of congenital left heart obstructive lesions appears promising and safe adjunct to more conventional management, the medium-term and long-term care of these patients remains as challenging as before.

Kidney function and population-based outcomes of initiating oral atenolol versus metoprolol tartrate in older adults

BACKGROUND

Atenolol and metoprolol tartrate are commonly prescribed β-blockers. Atenolol elimination depends on kidney function, whereas metoprolol tartrate does not. We hypothesized that compared to metoprolol tartrate, initiating oral atenolol treatment would be associated with more adverse events in older adults, with the association most pronounced in patients with lower baseline estimated glomerular filtration rates (eGFRs).

STUDY DESIGN

Population-based matched retrospective cohort study.

SETTING & PARTICIPANTS

Older adults (mean age, 75 years) in Ontario, Canada, prescribed oral atenolol versus metoprolol tartrate from April 2002 through December 2011. The 2 groups were well matched (n=75,257 in each group), with no difference in 31 measured baseline characteristics. Patients with end-stage renal disease were ineligible, and 4.6% of patients had chronic kidney disease (median eGFR, 38mL/min/1.73m(2) assessed through a database algorithm).

PREDICTORS

β-Blocker type and eGFR.

OUTCOMES

A composite outcome of hospitalization with bradycardia or hypotension and all-cause mortality were assessed in 90-day follow-up.

RESULTS

Compared to metoprolol tartrate, initiating atenolol treatment was not associated with higher risk of hospitalization with bradycardia or hypotension (incidence, 0.71% vs 0.79%; relative risk, 0.90; 95%CI, 0.80-1.01). Atenolol treatment initiation was associated with lower 90-day risk of mortality than metoprolol tartrate (incidence, 0.97% vs 1.44%; relative risk, 0.68; 95%CI, 0.61-0.74). Lower eGFR did not modify either association (P for interaction=0.5 and 0.6, respectively).

LIMITATIONS

Heart rate and blood pressure were not available in our data sources, and effects ascertained from observational studies are subject to residual confounding.

CONCLUSIONS

Contrary to our expectation, we found that atenolol versus metoprolol tartrate was associated with lower 90-day risk of mortality in patients regardless of eGFR, with no difference in risk of hospitalization with bradycardia or hypotension.

Heart rate reduction with ivabradine in patients with acute decompensated systolic heart failure

INTRODUCTION

In patients with acute decompensated systolic heart failure (ADSHF) high resting heart rate (HR) could be either a compensatory mechanism or contribute to worsening heart failure. The aim of this study was to evaluate, in patients with ADSHF and resting HR >70 bpm, the early (within 24 h) and late (at discharge) effects of oral administration of ivabradine on HR reduction.

METHODS

Ten consecutive patients with ADSHF, left ventricular ejection fraction <40 % and HR >70 bpm, without other acute conditions or inotropic therapy, began open-label treatment with oral ivabradine according to a pre-established Heart Failure Unit protocol. We obtained clinical and laboratory data at four periods: admission (T0), immediately before initiation of ivabradine (T2), 24 h after initiation of ivabradine (T3), and at discharge (T4).

RESULTS

Ivabradine was administered in 60 % of the patients before the second day. HR decreased 10.7 ± 7.2 bpm at T3 (p < 0.001) and 16.3 ± 8.2 bpm at T4 (p = 0.002). The systolic blood pressure decreased at T3 (p = 0.012), returning to baseline values at T4. There was no change in diastolic and mean blood pressure. New York Heart Association (NYHA) class improvement by two levels was associated with lower HR at T4 (p = 0.033). HR and N-terminal pro-brain natriuretic peptide (Nt-ProBNP) at baseline correlated significantly [Spearman correlation coefficient (rs) = 0.789, p = 0.013]. Total Nt-ProBNP reduction correlated with the HR before (r = 0.762, p = 0.028) and after (T3: r = 0.647, p = 0.083; T4: r = 0.738, p = 0.037) ivabradine addition.

CONCLUSION

In the present cohort of patients with ADSHF and HR >70 bpm, the selective reduction of HR with oral ivabradine was safe and efficient.

Association of resting heart rate with cardiovascular function: a cross-sectional study in 522 Finnish subjects

Background

High resting heart rate (HR) is associated with increased cardiovascular risk in general populations, possibly due to elevated blood pressure (BP) or sympathetic over-activity. We studied the association of resting HR with cardiovascular function, and examined whether the hemodynamics remained similar during passive head-up tilt.

Methods

Hemodynamics were recorded using whole-body impedance cardiography and continuous radial pulse wave analysis in 522 subjects (age 20–72 years, 261 males) without medication influencing HR or BP, or diagnosed diabetes, coronary artery, renal, peripheral arterial, or cerebrovascular disease. Correlations were calculated, and results analysed according to resting HR tertiles.

Results

Higher resting HR was associated with elevated systolic and diastolic BP, lower stroke volume but higher cardiac output and work, and lower systemic vascular resistance, both supine and upright (p < 0.05 for all). Subjects with higher HR also showed lower supine and upright aortic pulse pressure and augmentation index, and increased resting pulse wave velocity (p < 0.001). Upright stroke volume decreased less in subjects with highest resting HR (p < 0.05), and cardiac output decreased less in subjects with lowest resting HR (p < 0.009), but clear hemodynamic differences between the tertiles persisted both supine and upright.

Conclusions

Supine and upright hemodynamic profile associated with higher resting HR is characterized by higher cardiac output and lower systemic vascular resistance. Higher resting HR was associated with reduced central wave reflection, in spite of elevated BP and arterial stiffness. The increased cardiac workload, higher BP and arterial stiffness, may explain why higher HR is associated with less favourable prognosis in populations.

Trial registration

ClinicalTrials.gov, NCT01742702

Usefulness of combined risk stratification with heart rate and systolic blood pressure in the management of chronic heart failure. A report from the CHART-2 study

BACKGROUND

The appropriate target ranges of heart rate (HR) and systolic blood pressure (SBP) for the management of chronic heart failure (CHF) patients remain to be elucidated in a large-scale cohort study.

METHODS AND RESULTS

We examined 3,029 consecutive CHF patients with sinus rhythm (SR) (mean age, 67.9 years) registered in the Chronic Heart Failure Analysis and Registry in the Tohoku District-2 Study (CHART-2; NCT00418041). There were 357 deaths (11.8%) during the median follow-up of 3.1 years. We first performed the classification and regression tree analysis for mortality, identifying SBP <89 mmHg, HR >70 beats/min and SBP <115 mmHg as the primary, secondary and tertiary discriminators, respectively. According to these, we divided the patients into low- (n=1,131), middle- (n=1,624) and high-risk (n=274) groups with mortality risk <10%, 10-20% and >20%, respectively. The low-risk group was characterized by SBP >115 mmHg and HR <70 beats/min and the high-risk group by SBP <89 mmHg regardless of HR values or SBP 89-115 mmHg and HR >76 beats/min. Multivariate Cox regression analysis revealed that the hazard ratio of all-cause death for low-, middle- and high-risk groups was 1.00 (reference), 1.48 (95% confidence interval (CI): 1.10-1.99, P=0.009) and 2.44 (95% CI 1.66-3.58, P<0.001), respectively. Subgroup analysis revealed that age ≥70 years, diabetes, or reduced left ventricular function had higher hazard ratios in the high-risk group.

CONCLUSIONS

The results demonstrate the usefulness of combined risk stratification of HR and SBP in CHF patients with SR.

Association of resting heart rate with carotid and aortic arterial stiffness: multi-ethnic study of atherosclerosis

Resting heart rate is an easily measured, noninvasive vital sign that is associated with cardiovascular disease events. The pathophysiology of this association is not known. We investigated the relationship between resting heart rate and stiffness of the carotid (a peripheral artery) and the aorta (a central artery) in an asymptomatic multi-ethnic population. Resting heart rate was recorded at baseline in the Multi-Ethnic Study of Atherosclerosis (MESA). Distensibility was used as a measure of arterial elasticity, with a lower distensibility indicating an increase in arterial stiffness. Carotid distensibility was measured in 6484 participants (98% of participants) using B-mode ultrasound, and aortic distensibility was measured in 3512 participants (53% of participants) using cardiac MRI. Heart rate was divided into quintiles and we used progressively adjusted models that included terms for physical activity and atrioventricular nodal blocking agents. Mean resting heart rate of participants (mean age, 62 years; 47% men) was 63 bpm (SD, 9.6 bpm). In unadjusted and fully adjusted models, carotid distensibility and aortic distensibility decreased monotonically with increasing resting heart rate (P for trend <0.001 and 0.009, respectively). The relationship was stronger for carotid versus aortic distensibility. Similar results were seen using the resting heart rate taken at the time of MRI scanning. Our results suggest that a higher resting heart rate is associated with an increased arterial stiffness independent of atrioventricular nodal blocker use and physical activity level, with a stronger association for a peripheral (carotid) compared with a central (aorta) artery.

Resting heart rate and outcomes in patients with cardiovascular disease: where do we currently stand?

BACKGROUND

Data from large epidemiological studies suggest that elevated heart rate is independently associated with cardiovascular and all-cause mortality in patients with hypertension and in those with established cardiovascular disease. Clinical trial findings also suggest that the favorable effects of beta-blockers and other heart rate-lowering agents in patients with acute myocardial infarction and congestive heart failure may be, at least in part, due to their heart rate-lowering effects. Contemporary clinical outcome prediction models such as the Global Registry of Acute Coronary Events (GRACE) score include admission heart rate as an independent risk factor.

AIMS

This article critically reviews the key epidemiology concerning heart rate and cardiovascular risk, potential mechanisms through which an elevated resting heart rate may be disadvantageous and evaluates clinical trial outcomes associated with pharmacological reduction in resting heart rate.

CONCLUSIONS

Prospective randomised data from patients with significant coronary heart disease or heart failure suggest that intervention to reduce heart rate in those with a resting heart rate >70 bpm may reduce cardiovascular risk. Given the established observational data and randomised trial evidence, it now appears appropriate to include reduction of elevated resting heart rate by lifestyle +/- pharmacological therapy as part of a secondary prevention strategy in patients with cardiovascular disease.

Effect of plant polyphenols on ischemia-reperfusion injury of the isolated rat heart and vessels

In the present study, we investigated the potential protective effect of selected natural substances in a rat model of heart and mesenteric ischemia-reperfusion (I/R). Experiments were performed on isolated Langendorff-perfused rat hearts, subjected to 30-min global ischemia, followed by 30-min reperfusion. Arbutin, curcumin, rosmarinic acid and extract of Mentha x villosa were applied in the concentration of 1 × 10⁻⁵ mol/l 10 min before the onset of ischemia and during reperfusion, through the perfusion medium. Mesenteric ischemia was induced by clamping the superior mesenteric artery (SMA) for 60 min, subsequent reperfusion lasted 30 min. Production of reactive oxygen species (ROS) by SMA ex vivo was determined by luminol-enhanced chemiluminiscence (CL). The effect of the substances was tested after their incubation with tissue. Curcumin and extract of Mentha x villosa were found to be the most effective in reducing reperfusion-induced dysrhythmias--ventricular tachycardia and fibrillation. This effect was accompanied by bradycardic effect. The mesenteric I/R induced an increase in CL in vascular tissue which was dampened by substances tested. All substances tested were found to have antioxidant properties, as demonstrated by a reduction in ROS production in mesenteric vessels. This effect was confirmed in curcumin and extract of Mentha x villosa which reduced reperfusion dyshythmias.