The predictive value of admission heart rate on mortality in patients with acute myocardial infarction. SPRINT Study Group. Secondary Prevention Reinfarction Israeli Nifedipine Trial

Association between admission heart rate and in-hospital mortality in patients with acute exacerbation of chronic obstructive pulmonary disease and respiratory failure: a retrospective cohort study

BACKGROUND

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) combined with respiratory failure (RF) is a chronic respiratory disease that seriously endangers human health. This study aimed to specifically evaluate the relationship between admission heart rate (AHR) and in-hospital mortality in patients with combined AECOPD and RF to better inform clinical treatment.

METHODS

This retrospective cohort study included 397 patients admitted to a Chinese hospital between January 2021 and March 2023. The primary outcome measure was all-cause in-hospital mortality. Multivariate logistic regression analyses were performed to calculate adjusted hazard ratios (OR) with corresponding 95% confidence intervals (CI), and curve fitting and threshold effect were performed to address nonlinear relationships.

RESULTS

In total, 397 patients with AECOPD/RF were screened. The mean (± SD) age of the study cohort was 72.6 ± 9.5 years, approximately 49.4% was female, and the overall in-hospital mortality rate was 5%. Multivariate logistic regression analysis and smooth curve fitting revealed a nonlinear association between AHR and in-hospital mortality in the study population, with 100 beats/min representing the inflection point. Left of the inflection point, the effect size (OR) was 0.474 (95% CI 0.016 ~ 13.683; p = 0.6635). On the right side, each 1 beat/min increase in AHR resulted in an effect size (OR) of 1.094 (95% CI 1.01 ~ 1.186; p = 0.0281).

CONCLUSIONS

Results of the present study demonstrated a nonlinear relationship between AHR and in-hospital mortality in patients with AECOPD/RF. When AHR was < 100 beats/min, it was not statistically significant; however, AHR > 100 beats/min was a predictor of potential mortality, which increased by 9.4% for every 1 beat/min increase in AHR.

Association between admission heart rate and major adverse cardiovascular events in acute myocardial infarction participants with different left ventricular ejection fraction

BACKGROUND

This study intended to investigate the independent effect of admission heart rate (HR) on the risk of major adverse cardiovascular events (MACEs) in acute myocardial infarction (AMI) patients with different left ventricular ejection fraction (LVEF) levels.

METHODS

The study was a secondary analysis of the Acute Coronary Syndrome Quality Improvement in Kerela Trial. The relationship between admission HR and 30-day adverse outcomes in AMI patients with different LVEF levels was detected using a Logistic regression model. Interaction tests were used to compare the effects of different subgroups on HR and MACEs.

RESULTS

Our study enrolled 18,819 patients. In both partially and fully adjusted models (Model1 and Model2), the risk of MACEs was highest in patients with HR ≥ 120 (OR: 1.62, 95%CI: (1.16, 2.26), P = 0.004, Model1; OR: 1.46, 95%CI: (1.00, 2.12), P = 0.047, Model2). There was a significant interaction between LVEF and HR (P for interaction = 0.003). Meanwhile, the trend test for this association showed that HR was positively and significantly associated with the MACEs in LVEF≥40% group (OR (95%CI): 1.27 (1.12, 1.45), P < 0.001). However, in LVEF<40% group, the trend test was not statistically significant (OR (95%CI): 1.09 (0.93, 1.29), P = 0.269).

CONCLUSION

This study found that elevated admission HR was associated with a significantly higher risk for MACEs in patients admitted with AMI. Elevated admission HR was significantly associated with the risk of MACEs in AMI patients without low LVEF but not those with low LVEF (<40%). LVEF levels should be considered when evaluating the association between admission HR and the prognosis of AMI patients in the future.

Risk Factors for Arrhythmic Death, Overall Mortality, and Ventricular Tachyarrhythmias Requiring Shock After Myocardial Infarction

The VEST (Vest Prevention of Early Sudden Death Trial) showed a trend toward decreased sudden death and lower overall mortality with a wearable cardioverter-defibrillator (WCD) in the postmyocardial infarction (post-MI) period. However, it is unclear which patients should receive WCD therapy. We aimed to identify the risk factors for arrhythmic death, all-cause mortality, and ventricular tachyarrhythmias requiring appropriate shock to identify patients most likely to benefit from a WCD. The VEST trial included patients with acute MI with ejection fraction ≤35%. Using logistic regression, 7 risk factors were evaluated for association with arrhythmic death, all-cause mortality, and appropriate shock. Among 2,302 participants, 44 had arrhythmic death (1.9%) and 86 died of any cause (3.7%). Among 1,524 participants randomized to WCD, 20 experienced appropriate shock (1.3%) over 90 days. In the multivariable analyses, lower systolic blood pressure (SBP; odds ratio [OR] 1.64 per 10 mm Hg) and higher heart rate at discharge (OR 1.19 per 10 beats/min) were associated with arrhythmic death. Lower SBP (OR 1.37) and higher heart rate (OR 1.10) were associated with all-cause mortality. Higher heart rate (OR 1.20) was associated with appropriate shock. Patients with both SBP ≤100 and heart rate ≥100 were at increased odds of arrhythmic death (OR 4.82), all-cause mortality (OR 3.10), and appropriate shock (OR 6.13). In patients with acute MI and reduced ejection fraction, lower SBP and higher heart rate at discharge were strongly associated with arrhythmic death and all-cause mortality. In conclusion, these risk factors identify a select group at high risk of adverse events in a setting where WCD therapy is reasonable.

Prognostic impact of mean heart rate by Holter monitoring on long-term outcome in patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention

BACKGROUND

Previous studies have shown elevated admission heart rate (HR) was associated with worse outcome in patients with myocardial infarction (MI). However, the prognostic value of mean heart rate (MHR) with Holter monitoring remains unclear.

OBJECTIVES

Our present study aims to evaluate the impact of MHR by Holter monitoring on long-term mortality in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

1013 STEMI patients were divided into four groups according to the quartiles of MHR by Holter monitoring, Q1 (< 66 bpm), Q2 66-72 bpm), Q3 (73-78 bpm), and Q4 (> 78 bpm). The endpoint was long-term all-cause mortality. The predictive value of admission HR, discharge HR, and MHR was compared with receiver operating characteristic (ROC) curves.

RESULTS

Patients in Q4 were more likely to present with anterior MI, high Killip class, relatively lower admission blood pressure, significantly increased troponin I, B-type natriuretic peptide, and decreased left ventricular ejection fraction. During a median of 28.3 months follow up period, 91 patients (8.9%) died. The mortality in Q4 was significantly higher than in the other three groups (P < 0.001). After multivariate adjustment, Q4 was associated with a 1.0-fold increased risk of long-term all-cause mortality (HR = 2.096, 95% CI 1.190-3.691, P = 0.010). ROC analysis shows MHR with Holter (AUC = 0.672) was superior to admission HR (AUC = 0.556) or discharge HR (AUC = 0.578).

CONCLUSIONS

MHR based on Holter monitoring provided important prognostic value and MHR > 78 bpm was independently associated with increased risk of long-term all-cause mortality in patients with STEMI, and its predictive validity was superior to admission or discharge HR.

Heart rate at discharge in patients with acute decompensated heart failure is a predictor of mortality

Aims

Heart failure is a syndrome with increasing prevalence in concordance with the aging population and better survival rates from myocardial infarction. Morbidity and mortality are high in chronic heart failure patients, particularly in those with hospital admission for acute decompensation. Several risk stratification tools and score systems have been established to predict mortality in chronic heart failure patients. However, identification of patients at risk with easy obtainable clinical factors that can predict mortality in acute decompensated heart failure (ADHF) are needed to optimize the care-path.

Methods and results

We retrospectively analyzed electronic medical records of 78 patients with HFrEF and HFmrEF who were hospitalized with ADHF in the Heart Center of the University Hospital Cologne in the year 2011 and discharged from the ward after successful treatment. 37.6 ± 16.4 months after index hospitalization 30 (38.5%) patients had died. This mortality rate correlated well with the calculated predicted survival with the Seattle Heart Failure Model (SHFM) for each individual patient. In our cohort, we identified elevated heart rate at discharge as an independent predictor for mortality (p = 0.016). The mean heart rate at discharge was lower in survived patients compared to patients who died (72.5 ± 11.9 vs. 79.1 ± 11.2 bpm. Heart rate of 77 bpm or higher was associated with an almost doubled mortality risk (p = 0.015). Heart rate elevation of 5 bpm was associated with an increase of mortality of 25% (p = 0.022).

Conclusions

Patients hospitalized for ADHF seem to have a better prognosis, when heart rate at discharge is < 77 bpm. Heart rate at discharge is an easily obtainable biomarker for risk prediction of mortality in HFrEF and HFmrEF patients treated for acute cardiac decompensation. Taking into account this parameter could be useful for guiding treatment strategies in these high-risk patients. Prospective data for validation of this biomarker and specific intervention are needed.

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.

Prognostic value of discharge heart rate in acute heart failure patients: More relevant in atrial fibrillation?

Aims

The prognostic impact of heart rate (HR) in acute heart failure (AHF) patients is not well known especially in atrial fibrillation (AF) patients. The aim of the study was to evaluate the impact of admission HR, discharge HR, HR difference (admission-discharge) in AHF patients with sinus rhythm (SR) or AF on long- term outcomes.

Methods

We included 1398 patients consecutively admitted with AHF between October 2013 and December 2014 from a national multicentre, prospective registry. Logistic regression models were used to estimate the association between admission HR, discharge HR and HR difference and one- year all-cause mortality and HF readmission.

Results

The mean age of the study population was 72 ± 12 years. Of these, 594 (42.4%) were female, 655 (77.8%) were hypertensive and 655 (46.8%) had diabetes. Among all included patients, 745 (53.2%) had sinus rhythm and 653 (46.7%) had atrial fibrillation. Only discharge HR was associated with one year all-cause mortality (Relative risk (RR) = 1.182, confidence interval (CI) 95% 1.024–1.366, p = 0.022) in SR. In AF patients discharge HR was associated with one year all cause mortality (RR = 1.276, CI 95% 1.115–1.459, p ≤ 0.001). We did not observe a prognostic effect of admission HR or HRD on long-term outcomes in both groups. This relationship is not dependent on left ventricular ejection fraction.

Conclusions

In AHF patients lower discharge HR, neither the admission nor the difference, is associated with better long-term outcomes especially in AF patients.

Discharge Heart Rate After Hospitalization for Myocardial Infarction and Long-Term Mortality in 2 US Registries

Background

Although admission heart rate predicts higher mortality after acute myocardial infarction (AMI), less is known about discharge heart rate. We tested the hypothesis that higher discharge heart rate after AMI is related to increased long‐term mortality independent of admission heart rate, and assessed whether β blockers modify this relationship.

Methods and Results

In 2 prospective US multicenter registries of AMI, we evaluated the associations of discharge and admission heart rate with 3‐year mortality using Cox models. Among 6576 patients with AMI, discharge heart rate was modestly associated with initial heart rate (r=0.28), comorbidities, and infarct severity. In this cohort, 10.7% did not receive β blockers at discharge. After full adjustment for demographic, psychosocial, and clinical covariates, discharge heart rate (hazard ratio [HR]=1.14 per 10 beats per minute [bpm]; 95% CI=1.07–1.21 per 10 bpm) was more strongly associated with risk of death than admission heart rate (HR=1.05 per 10 bpm; 95% CI=1.02–1.09 per 10 bpm) when both were entered in the same model (P=0.043 for comparison). There was a significant interaction between discharge heart rate and β‐blocker use (P=0.004) on mortality, wherein risk of death was markedly higher among those with high discharge heart rate and not on β blockers (HR=1.35 per 10 bpm; 95% CI=1.19–1.53 per 10 bpm) versus those with a high discharge heart rate and on β blockers at discharge (HR=1.10 per 10 bpm; 95% CI=1.03–1.17 per 10 bpm).

Conclusions

Higher discharge heart rate after AMI was more strongly associated with 3‐year mortality than admission heart rate, and the risk associated with higher discharge heart rate was modified by β blockers at discharge. These findings highlight opportunities for risk stratification and intervention that will require further investigation.

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.

A Mathematical Model of dP/dt Max for the Evaluation of the Dynamic Control of Heart Contractility in Septic Shock

OBJECTIVE

Septic shock (SS) patients often show elevated heart rate (HR) despite resuscitation, and this condition is considered an early manifestation of myocardial dysfunction due to an impairment of autonomic nervous system (ANS). We aimed at proposing a mathematical model to assess the autonomic control of ventricular contractility (VC) and HR to track changes in heart functionality during an experimental animal model of SS and resuscitation.

METHODS

SS was induced in six adult swine by polymicrobial peritonitis. We analyzed the beat-to-beat variability of the maximum positive time derivative of left ventricular pressure (dP/dt max), heart period (HP), and aortic blood pressure (ABP). We identified the transfer functions relating fluctuations in ABP and HP to dP/dt max to characterize the static and dynamic properties of the arterial baroreflex and the force-frequency relation mechanisms, respectively. Standard indices of autonomic dysfunction have also been considered as HR variability (HRV) and baroreflex sensitivity (BRS).

RESULTS

During baseline, the baroreflex is predominant in controlling VC with a gain value of -5.8 (-7.5,-3) s^-1, compared to -1.2 (-1.9,-0.5) mmHg/s ms^-1 of the force-frequency autoregulation. During shock, both mechanisms increase their extent in VC control (higher gains and slightly faster dynamics for the baroreflex). After resuscitation, the physiological control of VC is not restored and all the animals still exhibit high HR and reduced HRV and BRS.

CONCLUSION

A condition of cardiovascular inefficiency is persistent after resuscitation and this could be due to autonomic dysfunction.

SIGNIFICANCE

The ANS in SS is crucial to restore homeostasis. Our model could be used to evaluate the efficacy of treatments on VC and related control mechanisms.

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.

Correlation of infarct size with invasive hemodynamics in patients with ST-elevation myocardial infarction

OBJECTIVES

To identify invasive hemodynamic parameters that correlate with infarction size in patients with ST-elevation myocardial infarction (STEMI).

BACKGROUND

Invasive hemodynamics obtained during primary percutaneous coronary intervention (PPCI) are predictive of mortality in STEMI, but which parameters correlate best with the size of the infarction are unknown.

METHODS

This is a single-center study of 405 adult patients with STEMI who had left ventricular end-diastolic pressure (LVEDP) measured during PPCI. Size of infarction was estimated by peak troponin I level and ejection fraction (LVEF) determined by echocardiography.

RESULTS

The average (±SD) age was 61 ± 14 years, TIMI STEMI risk score was 3.5 ± 2.7 and Grace score was 157 ± 42. Hemodynamic parameters that correlated best with EF were LVEDP (r = -0.40), PP (r = 0.24), and SBP/LVEDP ratio (r = 0.22) and with peak troponin were SBP/LVEDP ratio (r = -0.41), LVEDP (r = 0.31), and PP (r = -0.29). SBP/LVEDP (AUC = 0.76) and SBP (AUC = 0.77) had a stronger association with in-hospital mortality than did LVEDP (AUC = 0.66) or PP (AUC = 0.64). Door-to-balloon time did not affect the correlations between hemodynamic parameters and infarct size.

CONCLUSIONS

In this sample of 405 patients undergoing PPCI, SBP/LVEDP ratio had the strongest correlation with peak troponin levels and LVEDP with EF, whereas SBP/LVEDP and SBP had a strong association with in-hospital mortality. These results suggest that measurement of LVEDP as well as SBP may help risk stratify patients during PPCI.

MicroDAIMON study: Microcirculatory DAIly MONitoring in critically ill patients: a prospective observational study

Background

Until now, the prognostic value of microcirculatory alterations in critically ill patients has been mainly evaluated in highly selected subgroups. Aim of this study is to monitor the microcirculation daily in mixed group of Intensive Care Unit (ICU)-patients and to establish the association between (the evolution of) microcirculatory alterations and outcome.

Methods

This is a prospective longitudinal observational single-centre study in adult patients admitted to a 12-bed ICU in an Italian teaching hospital. Sublingual microcirculation was evaluated daily, from admission to discharge/death, using Sidestream Dark Field imaging. Videos were analysed offline to assess flow and density variables. Laboratory and clinical data were recorded simultaneously. A priori, a Microvascular Flow Index (MFI) < 2.6 was defined as abnormal. A binary logistic regression analysis was performed to evaluate the association between microcirculatory variables and outcomes; a Kaplan–Meier survival curve was built. Outcomes were ICU and 90-day mortality.

Results

A total of 97 patients were included. An abnormal MFI was present on day 1 in 20.6%, and in 55.7% of cases during ICU admission. Patients with a baseline MFI < 2.6 had higher ICU, in-hospital and 90-day mortality (45 vs. 15.6%, p = 0.012; 55 vs. 28.6%, p = 0.035; 55 vs. 26%, p = 0.017, respectively). An independent association between baseline MFI < 2.6 and outcome was confirmed in a binary logistic analysis (odds ratio 4.594 [1.340–15.754], p = 0.015). A heart rate (HR) ≥ 90 bpm was an adjunctive predictor of mortality. However, a model with stepwise inclusion of mean arterial pressure < 65 mmHg, HR ≥ 90 bpm, lactate > 2 mmol/L and MFI < 2.6 did not detect significant differences in ICU mortality. In case an abnormal MFI was present on day 1, ICU mortality was significantly higher in comparison with patients with an abnormal MFI after day 1 (38 vs. 6%, p = 0.001), indicating a time-dependent significant difference in prognostic value.

Conclusions

In a general ICU population, an abnormal microcirculation at baseline is an independent predictor for mortality. In this setting, additional routine daily microcirculatory monitoring did not reveal extra prognostic information. Further research is needed to integrate microcirculatory monitoring in a set of commonly available hemodynamic variables.

Trial registration NCT 02649088, www.clinicaltrials.gov. Date of registration: 23 December 2015, retrospectively registered

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0411-9) contains supplementary material, which is available to authorized users.

Increased heart rate on first day in Intensive Care Unit is associated with increased mortality

OBJECTIVE

To investigate the association of maximum HR during the first day of intensive care unit (ICU) and mortality.

METHODS

Data of 850 patients over 45 years of age, who were hospitalized in ICU, was retrospectively analyzed. They were divided into two groups; Group-I, patients with maximum HR<100/min Group-II, patients with maximum HR≥100/min on first day. The groups were compared regarding age, sex, use of beta-blockers, use of inotropic and vasopressor drugs, hemodynamic parameters, anemia, mechanical ventilation, length of hospitalization (ICU and total), mortality (ICU and total), and CHARLSON & APACHE-II scores.

RESULTS

The mean age of patients was 63±12 years and 86% were after non-cardiac surgery. Maximum HR was 83±11 in Group-I and 115±14/min in Group-II (p=0.002). Group-II patients had more frequent vasopressor and inotropic drugs usage, (p<0.001), anemia, mechanical ventilation (p<0.005), higher CHARLSON & APACHE-II scores, stayed longer in ICU and hospital, and had higher ICU and hospital mortality compared to group-I (p<0.05). APACHE-II scores and maximum HR<100/min were independent variables predicting ICU mortality in multivariate logistic regression analysis whereas usage of beta-blockers was not.

CONCLUSIONS

Our study showed that maximum HR less than100/minute during the first day of ICU is associated with decreased mortality in Intensive Care Unit.

Heart rate at admission is a predictor of in-hospital mortality in patients with acute coronary syndromes: Results from 58 European hospitals: The European Hospital Benchmarking by Outcomes in acute coronary syndrome Processes study

Aims:

The purpose of this study was to investigate the relationship between heart rate at admission and in-hospital mortality in patients with ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation acute coronary syndrome (NSTE-ACS).

Methods:

Consecutive ACS patients admitted in 2008–2010 across 58 hospitals in six participant countries of the European Hospital Benchmarking by Outcomes in ACS Processes (EURHOBOP) project (Finland, France, Germany, Greece, Portugal and Spain). Cardiogenic shock patients were excluded. Associations between heart rate at admission in categories of 10 beats per min (bpm) and in-hospital mortality were estimated by logistic regression in crude models and adjusting for age, sex, obesity, smoking, hypertension, diabetes, known heart failure, renal failure, previous stroke and ischaemic heart disease. In total 10,374 patients were included.

Results:

In both STEMI and NSTE-ACS patients, a U-shaped relationship between admission heart rate and in-hospital mortality was found. The lowest risk was observed for heart rates between 70–79 bpm in STEMI and 60–69 bpm in NSTE-ACS; risk of mortality progressively increased with lower or higher heart rates. In multivariable models, the relationship persisted but was significant only for heart rates >80 bpm. A similar relationship was present in both patients with or without diabetes, above or below age 75 years, and irrespective of the presence of atrial fibrillation or use of beta-blockers.

Conclusion:

Heart rate at admission is significantly associated with in-hospital mortality in patients with both STEMI and NSTE-ACS. ACS patients with admission heart rate above 80 bpm are at highest risk of in-hospital mortality.

Elevated heart rate and nondipping heart rate as potential targets for melatonin: a review

Elevated heart rate is a risk factor for cardiovascular and all-cause mortalities in the general population and various cardiovascular pathologies. Insufficient heart rate decline during the night, that is, nondipping heart rate, also increases cardiovascular risk. Abnormal heart rate reflects an autonomic nervous system imbalance in terms of relative dominance of sympathetic tone. There are only a few prospective studies concerning the effect of heart rate reduction in coronary heart disease and heart failure. In hypertensive patients, retrospective analyses show no additional benefit of slowing down the heart rate by beta-blockade to blood pressure reduction. Melatonin, a secretory product of the pineal gland, has several attributes, which predict melatonin to be a promising candidate in the struggle against elevated heart rate and its consequences in the hypertensive population. First, melatonin production depends on the sympathetic stimulation of the pineal gland. On the other hand, melatonin inhibits the sympathetic system in several ways representing potentially the counter-regulatory mechanism to normalize excessive sympathetic drive. Second, administration of melatonin reduces heart rate in animals and humans. Third, the chronobiological action of melatonin may normalize the insufficient nocturnal decline of heart rate. Moreover, melatonin reduces the development of endothelial dysfunction and atherosclerosis, which are considered a crucial pathophysiological disorder of increased heart rate and pulsatile blood flow. The antihypertensive and antiremodeling action of melatonin along with its beneficial effects on lipid profile and insulin resistance may be of additional benefit. A clinical trial investigating melatonin actions in hypertensive patients with increased heart rate is warranted.

Review: Angiotensin-converting enzyme inhibitors and coronary heart disease prevention

A number of large randomised controlled trials have shown that angiotensin-converting enzyme (ACE) inhibitors, compared with placebo or other blood pressure-lowering drugs, improve coronary heart disease outcomes (fatal and non-fatal myocardial infarction, and coronary revascularisation) in diverse patient groups, e.g. in primary and secondary prevention, those with and without left ventricular dysfunction, and among hypertensive and non-hypertensive subjects. An updated meta-regression analysis which included five major trials in patients with established coronary artery disease (CAD) (EUROPA, INVEST, ACTION, PEACE and CAMELOT) concluded that ACE inhibitor (ACE-I) therapy has clear benefits in secondary prevention, but there are important and unexplained differences between trials in clinical outcome, baseline cardiovascular risk, blood pressure changes and trial design which deserve further discussion of the underlying mechanisms and clinical interpretation. For example, in placebo-controlled trials the biggest (20—22%) reductions in primary end points (including mortality) have been observed with perindopril and ramipril, whereas trials using trandolapril and quinapril had no effect on survival or recurrent CAD events. This review summarises and compares the major findings of these recent trials, and provides further analysis of the underlying mechanisms and clinical significance of secondary CAD prevention with ACE-I therapy.

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 cardiovascular protection

Recent large epidemiological studies have confirmed that an elevated resting heart rate is an independent predictor of cardiovascular and overall mortality in the general population as well as in patients with hypertension, coronary heart disease and chronic heart failure. Pathophysiological studies indicate that a higher heart rate has detrimental effects that favor myocardial ischemia, ventricular arrhythmias, as well as an increase in vascular oxidative stress, endothelial dysfunction and atherosclerosis progression. Benefits of heart rate lowering drugs, such as beta-blockers and ivabradine, in reducing overall and cardiovascular-related mortality, have been demonstrated particularly in patients with coronary heart disease and heart failure. However, despite these evidences, resting heart rate is still an overlooked cardiovascular risk factor.

International study on microcirculatory shock occurrence in acutely ill patients

OBJECTIVES

Microcirculatory alterations are associated with adverse outcome in subsets of critically ill patients. The prevalence and significance of microcirculatory alterations in the general ICU population are unknown. We studied the prevalence of microcirculatory alterations in a heterogeneous ICU population and its predictive value in an integrative model of macro- and microcirculatory variables.

DESIGN

Multicenter observational point prevalence study.

SETTING

The Microcirculatory Shock Occurrence in Acutely ill Patients study was conducted in 36 ICUs worldwide.

PATIENTS

A heterogeneous ICU population consisting of 501 patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographic, hemodynamic, and laboratory data were collected in all ICU patients who were 18 years old or older. Sublingual Sidestream Dark Field imaging was performed to determine the prevalence of an abnormal capillary microvascular flow index (< 2.6) and its additional value in predicting hospital mortality. In 501 patients with a median Acute Physiology and Chronic Health Evaluation II score of 15 (10-21), a Sequential Organ Failure Assessment score of 5 (2-8), and a hospital mortality of 28.4%, 17% exhibited an abnormal capillary microvascular flow index. Tachycardia (heart rate > 90 beats/min) (odds ratio, 2.71; 95% CI, 1.67-4.39; p < 0.001), mean arterial pressure (odds ratio, 0.979; 95% CI, 0.963-0.996; p = 0.013), vasopressor use (odds ratio, 1.84; 95% CI, 1.11-3.07; p = 0.019), and lactate level more than 1.5 mEq/L (odds ratio, 2.15; 95% CI, 1.28-3.62; p = 0.004) were independent risk factors for hospital mortality, but not abnormal microvascular flow index. In reference to microvascular flow index, a significant interaction was observed with tachycardia. In patients with tachycardia, the presence of an abnormal microvascular flow index was an independent, additive predictor for in-hospital mortality (odds ratio, 3.24; 95% CI, 1.30-8.06; p = 0.011). This was not true for nontachycardic patients nor for the total group of patients.

CONCLUSIONS

In a heterogeneous ICU population, an abnormal microvascular flow index was present in 17% of patients. This was not associated with mortality. However, in patients with tachycardia, an abnormal microvascular flow index was independently associated with an increased risk of hospital death.

Resting heart rate in first year survivors of myocardial infarction and long-term mortality: a community study

OBJECTIVE

To evaluate the long-term prognostic effect of resting heart rate (HR) at index myocardial infarction (MI) and during the first year after MI among 1-year survivors.

PATIENTS AND METHODS

The community-based cohort consisted of 1571 patients hospitalized with an incident MI from January 1, 1983, through December 31, 2007, in Olmsted County, Minnesota, who were in sinus rhythm at index MI and had HR measurements on electrocardiography at index and during the first year after MI. Outcomes were all-cause and cardiovascular deaths.

RESULTS

During a median follow-up of 7.0 years, 627 deaths and 311 cardiovascular deaths occurred. Using patients with HRs of 60/min or less as the referent, this study found that long-term all-cause mortality risk increased progressively with increasing HR at index (hazard ratio, 1.62; 95% CI, 1.25-2.09) and even more with increasing HR during the first year after MI (hazard ratio, 2.16; 95% CI, 1.64-2.84) for patients with HRs greater than 90/min, adjusting for clinical characteristics and β-blocker use. Similar results were observed for cardiovascular mortality (adjusted hazard ratio, 1.66; 95% CI, 1.14-2.42; and adjusted hazard ratio, 1.93; 95% CI, 1.27-2.94; for HR at index and within 1 year after MI, respectively).

CONCLUSION

These data from a large MI community cohort indicate that HR is a strong predictor of long-term all-cause and cardiovascular mortality not only at initial presentation of MI but also during the first year of follow-up.

Measuring the acute cardiovascular effects of shisha smoking: a cross-sectional study

Objectives

To investigate the acute cardiovascular effects of smoking shisha.

Design

A cross-sectional study was carried out in six shisha cafes. Participants smoked shisha for a period between 45 min (minimum) and 90 min (maximum). The same brand of tobacco and coal was used.

Setting

London, UK.

Participants

Participants were those who had ordered a shisha to smoke and consented to have their blood pressure, heart rate and carbon monoxide levels measured. Excluded subjects were those who had smoked shisha in the previous 24 h, who smoke cigarettes or who suffered from cardiorespiratory problems.

Main outcome measures

Blood pressure was measured using a sphygmomanometer. Pulse was measured by palpation of the radial artery. Carbon monoxide levels were obtained via a carbon monoxide monitor. These indices were measured before the participants began to smoke shisha and after they finished or when the maximum 90 min time period was reached.

Results

Mean arterial blood pressure increased from 96 mmHg to 108 mmHg (p < 0.001). Heart rate increased from 77 to 91 bpm (p < 0.001). Carbon monoxide increased from an average of 3 to 35 ppm (p < 0.001). A correlation analysis showed no relationship between carbon monoxide and the other indices measured.

Conclusion

The acute heart rate, blood pressure and carbon monoxide levels were seen to rise significantly after smoking shisha. The weak correlation between carbon monoxide levels and the other variables suggests that carbon monoxide levels had not contributed to their significant increase.

Initial heart rate and cardiovascular outcomes in patients presenting with acute coronary syndrome

OBJECTIVES

To assess the impact of on-admission heart rate (HR) in patients presenting with acute coronary syndrome (ACS).

METHODS

Data were collected retrospectively from the second Gulf Registry of Acute Coronary Events. Patients were divided according to their initial HR into: (I: < 60, II: 60-69, III: 70-79, IV: 80-89 and V: ≥ 90 bpm). Patients' characteristics and hospital and one- and 12-month outcomes were analyzed and compared.

RESULTS

Among 7939 consecutive ACS patients, groups I to V represented 7%, 13%, 20%, 23.5%, and 37%, respectively. Mean age was higher in groups I and V. Group V were more likely males, diabetic and hypertensive. ST-elevation myocardial infarction was the main presentation in groups I and V. Reperfusion therapies were less likely given to group V. Beta blockers were more frequently prescribed to group III in comparison to groups with higher HR. Groups I and V were associated with worse hospital outcomes. Multivariate analysis showed initial tachycardia as an independent predictor for heart failure (OR 2.2; 95%CI: 1.39-3.32), while bradycardia was independently associated with higher one-month mortality (OR 2.0; 95%CI: 1.04-3.85) CONCLUSION: The majority of ACS patients present with tachycardia. However, low or high HR is a marker of high risk that needs more attention and management.

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.

Admission heart rate and in-hospital outcomes in patients hospitalized for heart failure in sinus rhythm and in atrial fibrillation

BACKGROUND

Prior studies have suggested an association between higher heart rate and higher mortality, particularly in chronic heart failure (HF). Whether this relationship holds true in patients hospitalized with HF and differs between patients in sinus rhythm (SR) and atrial fibrillation (AF) has not been well studied.

METHODS

We examined 145,221 admissions for HF from 295 hospitals enrolled in Get With The Guidelines-Heart Failure from January 2005 through September 2011. The associations of admission heart rate with in-hospital outcomes were evaluated overall and by heart rhythm.

RESULTS

Patients presenting at higher heart rate tended to be younger and have less comorbidities. In-hospital mortality had a J-shaped relationship with heart rate, with the lowest mortality rate associated with heart rates between 70 and 75. However, the relationship differed between patients presenting in SR and AF: at heart rates above 100, the mortality curve for AF plateaued, whereas that for SR continued to rise. Higher heart rate was independently associated with higher mortality (SR adjusted OR 1.21, 95% CI 1.15-1.28 per 10 beat per minute increase in heart rate between 70-105; AF adjusted OR 1.20, 95% CI 1.14-1.27). Findings were similar when stratifying patients by ischemic etiology, diabetes, ejection fraction, blood pressure, and β-blocker use.

CONCLUSIONS

Higher admission heart rate is independently associated with worse outcomes in patients admitted for HF, including those in SR and AF. Whether early heart rate reduction improves outcomes in patients hospitalized with HF is worthy of investigation.

Influence of resting heart rate on mortality in patients undergoing coronary angiography (from the Ludwigshafen Risk and Cardiovascular Health [LURIC] study)

Several epidemiologic studies have reported an association between elevated heart rate (HR) at rest and reduced survival. The usefulness of HR at rest in predicting end points in high-risk patients is yet to be definitively established. The purpose of this study was to clarify the relation between HR at rest with total and cardiovascular mortality in patients who underwent coronary angiography. A total of 3,316 Caucasian patients with available coronary angiograms were prospectively followed from 2001 to 2011 (median 9.9 years). The effect of HR at rest on total and cardiovascular mortality was explored, while correcting for a number of confounders. Patients in the highest quartile (HR at rest ≥ 84 beats/min) had survival times reduced by 1.2 and 1.4 years for overall and cardiovascular mortality, respectively. Likewise, these patients had significantly elevated adjusted risk for total (hazard ratio 1.39, 95% confidence interval 1.17 to 1.67, p for trend <0.001) and cardiovascular mortality (hazard ratio 1.38, 95% confidence interval 1.08 to 1.78, p for trend = 0.004). In conclusion, HR at rest is an inexpensive, easily measured, and modifiable predictor of mortality.

Resting heart rate in patients with ischemic heart disease in Saudi Arabia and Egypt

AIM

To assess the level of resting heart rate (RHR) in an outpatient population presenting with stable coronary artery disease (CAD) as well as to measure its association with current therapeutic management strategies for cardiovascular events.

MATERIALS AND METHODS

A multi-center cross-sectional survey was carried out in Saudi Arabia and Egypt over a three month period (between January 2007 and April 2007). 2049 patients with CAD without clinical heart failure (HF) were included in this study through "cluster sampling". RHR was measured by manual palpitation.

RESULTS

Mean age of CAD patients was 56.7 ± 10.4 and the mean RHR was 78.9 ± 13.9 b/m. 1686 patients (83.1%) were on β-blockers for whom the RHR was 78.5 ± 14.0 b/m (95.5% had RHR ⩾ 60 b/m, which is higher than recommended by the guidelines). 1094 (73.5%) of patients on β-blockers were on a lower dose, probably to avoid the complications associated with such a class. Among those not on β-blockers (16.9%), RHR was 80.9 ± 13.0 b/m. Moreover, 98 patients (4.8%) were on calcium channel blocker (diltiazem or verapamil) but not on β-blockers, for whom the RHR was 80.9 ± 12.0 b/m. Finally, 163 patients (8.0%) were on both β-blockers and the calcium channel blocker, and their RHR was 79.0 ± 14.4 b/m.

CONCLUSION

Optimal target RHR has not been achieved in a significant number of screened patients. Achievements of such targets are known to decrease mortality and to improve survival.

Factors Associated With Outcome in Heart Failure With Preserved Ejection Fraction

Background—

The determinants of prognosis in patients with heart failure and preserved ejection fraction (HF-PEF) are poorly documented.

Methods and Results—

We evaluated data from 4128 patients in the I-PRESERVE trial (Irbesartan in Heart Failure with Preserved Ejection Fraction Study). Multivariable Cox regression models were developed using 58 baseline demographic, clinical, and biological variables to model the primary outcome of all-cause mortality or cardiovascular hospitalization (1505 events), all-cause mortality (881 events), and HF death or hospitalization (716 events). Log N-terminal pro–B-type natriuretic peptide, age, diabetes mellitus, and previous hospitalization for HF were the most powerful factors associated with the primary outcome and with the HF composite. For all-cause mortality, log N-terminal pro–B-type natriuretic peptide, age, diabetes mellitus, and left ventricular EF were the strongest independent factors. Other independent factors associated with poor outcome included quality of life, a history of chronic obstructive lung disease, log neutrophil count, heart rate, and estimated glomerular filtration rate. The models accurately stratified the actual 3-year rate of outcomes from 8.1% to 59.9% (primary outcome) 2.7% to 36.5% (all-cause mortality), and 2.1% to 38.9% (HF composite) for the lowest to highest septiles of predicted risks.

Conclusions—

In a large sample of elderly patients with HF and preserved EF enrolled in I-Preserve, simple clinical, demographic, and biological variables were associated with outcome and identified subgroups at very high and very low risk of events.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00095238.

Usefulness of heart rate at rest as a predictor of mortality, hospitalization for heart failure, myocardial infarction, and stroke in patients with stable coronary heart disease (Data from the Treating to New Targets [TNT] trial)

The heart rate at rest (HR) is a predictor of cardiovascular (CV) mortality. However, its effect on nonfatal CV events is unknown. The aim of the present post hoc analysis of the Treating New Targets (TNT) trial was to assess the effect of the HR at rest on major CV events in patients with stable coronary heart disease. A total of 9,580 subjects were included in the present analysis and were followed up for a median of 4.9 years. The rate of major CV events was 11.9% in those with a baseline HR of > or =70 beats/min versus 8.8% in those with a baseline HR of <70 beats/min. An increased HR at rest was associated with CV events, even after adjustment for differences in baseline characteristics (unadjusted hazard ratio 1.16 for every 10-beats/min increase, 95% confidence interval [CI] 1.10 to 1.23, p <0.0001; adjusted hazard ratio 1.08 per 10-beats/min increase, 95% CI 1.02 to 1.16, p = 0.018). A HR > or =70 beats/min was a significant independent predictor of all-cause mortality (hazard ratio 1.40, 95% CI 1.14 to 1.71, p = 0.001) and heart failure hospitalization (hazard ratio 2.30, 95% CI 1.80 to 2.95, p > or =0.0001). However, this association was not observed for stroke or myocardial infarction (p = 0.11 and p = 0.68, respectively). In conclusion, in patients with stable coronary heart disease, every 10-beats/min increase in the HR at rest was associated with an 8% increase in major CV events. In particular, a HR at rest of > or =70 beats/min was associated with a 40% increased risk of all-cause mortality and more than doubled the risk of heart failure hospitalization, but not the risk of stroke or myocardial infarction.

Elevated heart rate and cardiovascular outcomes in patients with coronary artery disease: clinical evidence and pathophysiological mechanisms

There is an established body of evidence from epidemiological studies which indicates that an elevated resting heart rate is independently associated with atherosclerosis and increased cardiovascular morbidity and mortality, in both the general population and in patients with established cardiovascular disease. Clinical trial data suggest that in patients with coronary artery disease, an elevated heart rate identifies those at increased risk of adverse cardiovascular outcomes, and that lowering of heart rate may reduce major cardiovascular events in patients with an elevated heart rate and symptom-limiting angina. These results suggest that an increased heart rate may have an adverse impact on the atherosclerotic process and increase the risk of a cardiovascular event in patients with coronary artery disease. The precise pathophysiological mechanisms that link heart rate and cardiovascular outcomes have yet to be defined. Possibilities may include indirect mechanisms related to autonomic dysregulation and those due to an increase in heart rate per se, which can increase the ischaemic burden and exert local haemodynamic forces that can adversely impact on the endothelium and arterial wall. For these reasons, heart rate should be considered as a therapeutic target in the treatment of patients with coronary artery disease.

Association of arterial blood pressure and vasopressor load with septic shock mortality: a post hoc analysis of a multicenter trial

Introduction

It is unclear to which level mean arterial blood pressure (MAP) should be increased during septic shock in order to improve outcome. In this study we investigated the association between MAP values of 70 mmHg or higher, vasopressor load, 28-day mortality and disease-related events in septic shock.

Methods

This is a post hoc analysis of data of the control group of a multicenter trial and includes 290 septic shock patients in whom a mean MAP ≥ 70 mmHg could be maintained during shock. Demographic and clinical data, MAP, vasopressor requirements during the shock period, disease-related events and 28-day mortality were documented. Logistic regression models adjusted for the geographic region of the study center, age, presence of chronic arterial hypertension, simplified acute physiology score (SAPS) II and the mean vasopressor load during the shock period was calculated to investigate the association between MAP or MAP quartiles ≥ 70 mmHg and mortality or the frequency and occurrence of disease-related events.

Results

There was no association between MAP or MAP quartiles and mortality or the occurrence of disease-related events. These associations were not influenced by age or pre-existent arterial hypertension (all P > 0.05). The mean vasopressor load was associated with mortality (relative risk (RR), 1.83; confidence interval (CI) 95%, 1.4-2.38; P < 0.001), the number of disease-related events (P < 0.001) and the occurrence of acute circulatory failure (RR, 1.64; CI 95%, 1.28-2.11; P < 0.001), metabolic acidosis (RR, 1.79; CI 95%, 1.38-2.32; P < 0.001), renal failure (RR, 1.49; CI 95%, 1.17-1.89; P = 0.001) and thrombocytopenia (RR, 1.33; CI 95%, 1.06-1.68; P = 0.01).

Conclusions

MAP levels of 70 mmHg or higher do not appear to be associated with improved survival in septic shock. Elevating MAP >70 mmHg by augmenting vasopressor dosages may increase mortality. Future trials are needed to identify the lowest acceptable MAP level to ensure tissue perfusion and avoid unnecessary high catecholamine infusions.

Defibrillator implantation early after myocardial infarction

BACKGROUND

The rate of death, including sudden cardiac death, is highest early after a myocardial infarction. Yet current guidelines do not recommend the use of an implantable cardioverter-defibrillator (ICD) within 40 days after a myocardial infarction for the prevention of sudden cardiac death. We tested the hypothesis that patients at increased risk who are treated early with an ICD will live longer than those who receive optimal medical therapy alone.

METHODS

This randomized, prospective, open-label, investigator-initiated, multicenter trial registered 62,944 unselected patients with myocardial infarction. Of this total, 898 patients were enrolled 5 to 31 days after the event if they met certain clinical criteria: a reduced left ventricular ejection fraction (< or = 40%) and a heart rate of 90 or more beats per minute on the first available electrocardiogram (ECG) (criterion 1: 602 patients), nonsustained ventricular tachycardia (> or = 150 beats per minute) during Holter monitoring (criterion 2: 208 patients), or both criteria (88 patients). Of the 898 patients, 445 were randomly assigned to treatment with an ICD and 453 to medical therapy alone.

RESULTS

During a mean follow-up of 37 months, 233 patients died: 116 patients in the ICD group and 117 patients in the control group. Overall mortality was not reduced in the ICD group (hazard ratio, 1.04; 95% confidence interval [CI], 0.81 to 1.35; P=0.78). There were fewer sudden cardiac deaths in the ICD group than in the control group (27 vs. 60; hazard ratio, 0.55; 95% CI, 0.31 to 1.00; P=0.049), but the number of nonsudden cardiac deaths was higher (68 vs. 39; hazard ratio, 1.92; 95% CI, 1.29 to 2.84; P=0.001). Hazard ratios were similar among the three groups of patients categorized according to the enrollment criteria they met (criterion 1, criterion 2, or both).

CONCLUSIONS

Prophylactic ICD therapy did not reduce overall mortality among patients with acute myocardial infarction and clinical features that placed them at increased risk. (ClinicalTrials.gov number, NCT00157768.)

Role of exercise in the prevention of obesity and hemodynamic abnormalities in adolescents

BACKGROUND

Poor physical activity plays a key role in the development of obesity. Little is known, however, about how much or the level of intensity of exercise that is needed to prevent obesity and hemodynamic abnormalities in adolescents.

METHODS AND RESULTS

Height, bodyweight, resting heart rate (HR), and systolic and diastolic blood pressure was measured in 17,523 male and 16,906 female high school students. Self-reported exercise intensity was related to percentage of overweight (POW), diastolic blood pressure, and resting HR in boys, and to bodyweight and resting HR in girls. Self-reported exercise amount was associated with POW, diastolic blood pressure, and resting HR in both boys and girls. Also, high intensity or adequate amount of exercise was associated with a lower prevalence of obesity and resting tachycardia in both sexes, and slightly associated with the prevalence of systolic high blood pressure in boys.

CONCLUSION

Both intensity and amount of exercise are associated with the prevalence of obesity and hemodynamic abnormalities in adolescents.

Heart rate as a treatable cardiovascular risk factor

BACKGROUND

Although several epidemiological studies demonstrate the association between resting heart rate (HR) and cardiovascular morbidity and mortality, an elevated HR remains a neglected cardiovascular risk factor.

SOURCES OF DATA

This review summarizes the results of published studies on the relationship between elevated HR and cardiovascular risk.

AREAS OF AGREEMENT

The role of HR in myocardial ischaemia in coronary patients is well known. Experimental data and clinical observations support the importance of HR in the pathophysiology of atherosclerosis and plaque rupture. A large body of evidence points to high resting HR as a risk factor for mortality in various populations, including coronary patients.

AREAS OF CONTROVERSY

HR reduction is suggested to be a mechanism explaining the prognostic benefit of beta-blockers after myocardial infarction or in heart failure patients. However, it was unclear whether HR reduction per se directly affects cardiovascular prognosis. Treatment with ivabradine, a pure HR-reducing agent, provides an opportunity to assess the effects of selectively lowering HR without altering other aspects of cardiac function.

GROWING POINTS

The results of the recent Morbidity-Mortality Evaluation of the I(f) Inhibitor Ivabradine in Patients with Coronary Disease and Left Ventricular Dysfunction study underline the importance of HR reduction in the management of stable coronary artery disease. The prospective analysis of data from the placebo arm demonstrated that elevated resting HR (>or=70 bpm) is a strong independent predictor of clinical outcomes. Consistent with these data, ivabradine significantly improved coronary outcomes in patients with a HR of 70 bpm or more. AREAS TIMELY FOR DEVELOPMENT: These data support the importance of HR in the management of stable coronary artery disease to assess prognosis and to guide optimal therapy.

Assessment of autonomic function in cardiovascular disease: physiological basis and prognostic implications

Certain abnormalities of autonomic function in the setting of structural cardiovascular disease have been associated with an adverse prognosis. Various markers of autonomic activity have received increased attention as methods for identifying patients at risk for sudden death. Both the sympathetic and the parasympathetic limbs can be characterized by tonic levels of activity, which are modulated by, and respond reflexively to, physiological changes. Heart rate provides an index of the net effects of autonomic tone on the sinus node, and carries prognostic significance. Heart rate variability, though related to heart rate, assesses modulation of autonomic control of heart rate and carries additional prognostic information, which in some cases is more powerful than heart rate alone. Heart rate recovery after exercise represents the changes in autonomic tone that occur immediately after cessation of exercise. This index has also been shown to have prognostic significance. Autonomic evaluation during exercise and recovery may be important prognostically, because these are high-risk periods for sudden death, and the autonomic changes that occur with exercise could modulate this high risk. These markers provide related, but not redundant information about different aspects of autonomic effects on the sinus node.

Impact of resting heart rate on outcomes in hypertensive patients with coronary artery disease: findings from the INternational VErapamil-SR/trandolapril STudy (INVEST)

AIM

To determine the relationship between resting heart rate (RHR) and adverse outcomes in coronary artery disease (CAD) patients treated for hypertension with different RHR-lowering strategies.

METHODS AND RESULTS

Time to adverse outcomes (death, non-fatal myocardial infarction, or non-fatal-stroke) and predictive values of baseline and follow-up RHR were assessed in INternational VErapamil-SR/trandolapril STudy (INVEST) patients randomized to either a verapamil-SR (Ve) or atenolol (At)-based strategy. Higher baseline and follow-up RHR were associated with increased adverse outcome risks, with a linear relationship for baseline RHR and J-shaped relationship for follow-up RHR. Although follow-up RHR was independently associated with adverse outcomes, it added less excess risk than baseline conditions such as heart failure and diabetes. The At strategy reduced RHR more than Ve (at 24 months, 69.2 vs. 72.8 beats/min; P < 0.001), yet adverse outcomes were similar [Ve 9.67% (rate 35/1000 patient-years) vs. At 9.88% (rate 36/1000 patient-years, confidence interval 0.90-1.06, P = 0.62)]. For the same RHR, men had a higher risk than women.

CONCLUSION

Among CAD patients with hypertension, RHR predicts adverse outcomes, and on-treatment RHR is more predictive than baseline RHR. A Ve strategy is less effective than an At strategy for lowering RHR but has a similar effect on adverse outcomes.

Selective and specific I(f) inhibition: new perspectives for the treatment of stable angina

Ivabradine is the first selective and specific inhibitor of the I(f) current (the cardiac pacemaker 'funny' current), and provides pure heart rate reduction without altering myocardial contractility, the cardiac conduction system or coronary vascular resistance. Clinical proof of the antianginal efficacy and tolerability of ivabradine comes from the largest clinical development programme that has ever been performed in stable angina, involving more than 5000 patients. Ivabradine was shown to be as effective as well-established reference antianginal drugs, such as beta-blockers and calcium antagonists. It is well tolerated and is free of the most commonly observed side effects of currently prescribed antianginal drugs. It offers clear therapeutic benefits for a whole range of patients with stable angina, including those with contraindications or intolerance to beta-blockers.