Lower heart rate is associated with good one-year outcome in post-resuscitation patients

Factors predicting mortality in the cardiac ICU during the early phase of targeted temperature management in the treatment of post-cardiac arrest syndrome - The RAPID score

Introduction

Survival rates after out-of-hospital cardiac arrest (OHCA) remain low, and early prognostication is challenging. While numerous intensive care unit scoring systems exist, their utility in the early hours following hospital admission, specifically in the targeted temperature management (TTM) population, is questionable. Our aim was to create a score system that may accurately estimate outcome within the first 12 h after admission in patients receiving TTM.

Methods

We analyzed data from 103 OHCA patients who subsequently underwent TTM between 2016 and 2022. Patient demographic data, prehospital characteristics, clinical and laboratory parameters were already available in the first 12 h after admission were collected. Following a bootstrap-based predictor selection, we constructed a nonlinear logistic regression model. Internal validation was performed using bootstrap resampling. Discrimination was described using the c-statistic, whereas calibration was characterized by the intercept and slope.

Results

According to the Akaike Information Criterion (AIC) heart rate (AIC = 9.24, p = 0.0013), age (AIC = 4.39, p = 0.0115), pH (AIC = 3.68, p = 0.0171), initial rhythm (AIC = 4.76, p = 0.0093) and right ventricular end-diastolic diameter (AIC = 2.49, p = 0.0342) were associated with 30-day mortality and were used to build our predictive model and nomogram. The area under the receiver-operating characteristics curve for the model was 0.84. The model achieved a C-statistic of 0.7974, with internally validated acceptable calibration (intercept: -0.0190, slope: 0.7772) and low error rates (mean absolute error: 0.040).

Conclusion

The model we have developed may be suitable for early risk assessment of patients receiving TTM as part of primary post-resuscitation care. The calculator needed for scoring can be accessed at the following link: https://www.rapidscore.eu/.

Heart rate and heart rate variability as a prognosticating feature for functional outcome after cardiac arrest: A scoping review

Background

Despite significant progress in cardiopulmonary resuscitation and post-cardiac arrest care, favorable outcome in out-of hospital sudden cardiac arrest patients remains low. One of the main reasons for mortality in these patients is withdrawal of life-sustaining treatment. There is a need for precise and equitable prognostication tools to support families in avoiding premature or inappropriate WLST. Heart rate (HR) and heart rate variability (HRV) have been noted for their association with outcome, and are positioned to be a useful modality for prognostication.

Objectives

The aim of this scoping review is to rigorously explore which electrocardiography features have been shown to predict functional outcome in post-cardiac arrest patients.

Methods

The search was performed in Pubmed, EMBASE, and SCOPUS for studies published from January 1, 2011, to September 29, 2022, including papers in English or Korean.

Results

Seven studies were included with a total of 1359 patients. Four studies evaluated HR, one study evaluated RR inverval, and two studies evaluated HRV. All studies were retrospective, with 3 multi-center and 4 single-center studies. All seven studies were inclusive of patients who underwent targeted temperature management (TTM) after cardiac arrest, and two studies included patients without TTM. Five studies used cerebral performance category to assess functional outcome, two studies used Glasgow outcome score, and one study used modified Rankin scale. Three studies measured outcome at hospital discharge, one study measured outcome at 14 days after return of spontaneous circulation, two studies measured outcome after 3 months, and one after 1 year. In all studies that evaluated HR, lower HR was associated with favorable functional outcome. Two studies found that higher complexity of HRV was associated with favorable functional outcome.

Conclusion

HR and HRV showed clear associations with functional outcome in patients after CA, but cinilcial utility for prognostication is uncertain.

Heart rate and diastolic arterial pressure in cardiac arrest patients: A nationwide, multicenter prospective registry

Background

Guidelines have recommended monitoring mean arterial pressure (MAP) and systolic arterial pressure (SAP) in cardiac arrest patients, but there has been relatively little regard for diastolic arterial pressure (DAP) and heart rate (HR). We aimed to determine the prognostic significance of hemodynamic parameters at all time points during targeted temperature management (TTM).

Methods

We reviewed the SAP, DAP, MAP, and HR data in out-of-hospital cardiac arrest (OHCA) survivors from the prospective multicenter registry of 22 teaching hospitals. This study included 1371 patients who underwent TTM among 10,258 cardiac arrest patients. The hemodynamic parameters were recorded every 6 hours from the return of spontaneous circulation (ROSC) to 4 days. The risks of those according to time points during TTM were compared.

Results

Of the included patients, 943 (68.8%) had poor neurological outcomes. The predictive ability of DAP surpassed that of SAP and MAP at all time points, and among the hemodynamic variables HR/DAP was the best predictor of the poor outcome. The risks in patients with DAP < 55 to 70 mmHg and HR > 70 to 100 beats/min were steeply increased for 2 days after ROSC and correlated with the poor outcome at all time points. Bradycardia showed lower risks only at 6 hours to 24 hours after ROSC.

Conclusion

Hemodynamic parameters should be intensively monitored especially for 2 days after ROSC because cardiac arrest patients may be vulnerable to hemodynamic instability during TTM. Monitoring HR/DAP can help access the risks in cardiac arrest patients.

Beneficial Effects of Ivabradine on Post-Resuscitation Myocardial Dysfunction in a Porcine Model of Cardiac Arrest

Background:

Ivabradine selectively inhibits the If current, reducing the heart rate and protecting against myocardial ischemia/reperfusion injury. We investigated the effects of ivabradine on post-resuscitation myocardial function in a porcine model of cardiopulmonary resuscitation.

Methods and Results:

Ventricular fibrillation was induced and untreated for 8 min while defibrillation was attempted after 6 min of cardiopulmonary resuscitation in anesthetized domestic swine. Then the animals were randomized into ivabradine and placebo groups (n = 5 each). Ivabradine and saline were administered at the same volume 5 min after Return of Spontaneous Circulation, followed by continuous intravenous infusion at 0.5 mg/kg for 480 min. Hemodynamic parameters were continuously recorded. Myocardial function was assessed by echocardiography at baseline and at 60, 120, 240, 480 min and 24 h after resuscitation. The serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI) were measured by commercial enzyme-linked immunosorbent assay kits. Animals were killed 24 h after resuscitation, and all myocardial tissue was removed for histopathological analysis. The heart rate was significantly reduced from 1 h after resuscitation in the ivabradine group (all P < 0.05). The post-resuscitation mitral E/A and E/e′ velocity ratios and left ventricular ejection fraction were significantly better in the ivabradine than placebo group (P < 0.05). The serum levels of myocardial injury biomarkers (NT-proBNP, cTnI) and the myocardial biopsy scores were significantly lower in the ivabradine than placebo group (P < 0.05). Neurological deficit scores were lower in the IVA group at PR 24 h (P < 0.05).

Conclusions:

Ivabradine improved post-resuscitation myocardial dysfunction, myocardial injury, and post-resuscitation cerebral function, and also slowed the heart rate in this porcine model.

Effect of heart rate on hospital mortality in critically ill patients may be modified by age: a retrospective observational study from large database

BACKGROUND

Heart rate has been found associated with mortality in critically ill patients. However, whether the association differs between the elderly and non-elderly patients was unknown.

METHODS

We conducted a retrospective observational study of adult patients admitted to the intensive care unit (ICU) in the United States. Demographic, vital signs, laboratory tests, and interventions were extracted and compared between the elderly and non-elderly patients. The main exposure was heart rate, the proportion of time spent in heart rate (PTS-HR) was calculated. The primary outcome was hospital mortality. The multivariable logistic regression model was performed to assess the relationship between PTS-HR and hospital mortality, and interaction between PTS-HR and age categories was explored.

RESULTS

104,276 patients were included, of which 52,378 (50.2%) were elderly patients and 51,898 (49.8%) were non-elderly patients. The median age was 66 (IQR 54-76) years. After adjusting for confounders, PTS-HR < 60 beats per minute (bpm) (OR 0.972, 95% CI [0.945, 0.998], p = 0.031, P_interaction = 0.001) and 60-80 bpm (OR 0.925, 95% CI [0.912, 0.938], p < 0.001, P_interaction = 0.553) were associated with decreased risk of mortality; PTS-HR 80-100 bpm was associated with decreased mortality in the non-elderly patients (OR 0.955, 95% CI [0.941,0.975], p < 0.001) but was associated with increased mortality in the very elderly patients (OR 1.018, 95% CI [1.003,1.029], p = 0.017, P_interaction < 0.001). PTS-HR > 100 bpm (OR 1.093, 95% CI [1.081,1.105], p < 0.001, P_interaction = 0.004) was associated with increased mortality.

CONCLUSIONS

The effect of heart rate on hospital mortality differs between the elderly and non-elderly critically ill patients.

European Resuscitation Council and European Society of Intensive Care Medicine guidelines 2021: post-resuscitation care

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have collaborated to produce these post-resuscitation care guidelines for adults, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include the post-cardiac arrest syndrome, diagnosis of cause of cardiac arrest, control of oxygenation and ventilation, coronary reperfusion, haemodynamic monitoring and management, control of seizures, temperature control, general intensive care management, prognostication, long-term outcome, rehabilitation and organ donation.

European Resuscitation Council and European Society of Intensive Care Medicine Guidelines 2021: Post-resuscitation care

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have collaborated to produce these post-resuscitation care guidelines for adults, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include the post-cardiac arrest syndrome, diagnosis of cause of cardiac arrest, control of oxygenation and ventilation, coronary reperfusion, haemodynamic monitoring and management, control of seizures, temperature control, general intensive care management, prognostication, long-term outcome, rehabilitation, and organ donation.

Heart Rate and Neurological Outcomes in Patients Undergoing Targeted Temperature Management

INTRODUCTION

There is a paucity of data evaluating the impact of heart rate (HR) during Targeted Temperature Management (TTM) and neurologic outcomes. Current resuscitation guidelines do not specify a HR goal during TTM. We sought to determine the relationship between HR and neurologic outcomes in a single-center registry dataset.

METHODS

We retrospectively studied 432 consecutive patients who completed TTM (33°C) after cardiac arrest from 2008 to 2017. We evaluated the relationship between neurologic outcomes and HR during TTM. Pittsburgh Cerebral Performance Categories (CPC) at discharge were used to determine neurological recovery. Statistical analysis included chi square, Student's t-test and Mann-Whitney U. A logistic regression model was created to evaluate the strength of contribution of selected variables on the outcome of interest.

RESULTS

Approximately 94,000 HR data points from 432 patients were retrospectively analyzed; the mean HR was 82.17 bpm over the duration of TTM. Favorable neurological outcomes were seen in 160 (37%) patients. The mean HR in the patients with a favorable outcome was lower than the mean HR of those with an unfavorable outcome (79.98 bpm vs 85.67 bpm p < 0.001). Patients with an average HR of 60-91 bpm were 2.4 times more likely to have a favorable neurological outcome compared to than HR's < 60 or > 91 (odds ratio [OR] = 2.36, 95% confidence interval [CI] 1.61-3.46, p < 0.001). Specifically, mean HR's in the 73-82 bpm range had the greatest rate of favorable outcomes (OR 3.56, 95% CI 1.95-6.50), p < 0.001. Administration of epinephrine, a history of diabetes mellitus and hypertension all were associated with worse neurological outcomes independent of HR.

CONCLUSION

During TTM, mean HRs between 60-91 showed a positive association with favorable outcomes. It is unclear whether a specific HR should be targeted during TTM or if heart rates between 60-91 bpm might be a sign of less neurological damage.

Cardiac function after cardiac arrest: what do we know?

Postcardiac arrest myocardial dysfunction (PCAMD) is a frequent complication faced during post-resuscitation care that adversely impacts survival and neurological outcome. Both mechanical and electrical factors contribute to the occurrence of PCAMD. Prearrest ventricular function, the cause of cardiac arrest, global ischemia, resuscitation factors, ischemia/reperfusion injury and post-resuscitation treatments contribute to the severity of PCMAD. The pathophysiology of PCAMD is complex and include myocytes energy failure, impaired contractility, cardiac edema, mitochondrial damage, activation of inflammatory pathways and the coagulation cascade, persistent ischemic injury and myocardial stiffness. Hypotension and low cardiac output with vasopressor/inotropes need are frequent after resuscitation. However, clinical, hemodynamic and laboratory signs of shock are frequently altered by cardiac arrest pathophysiology and post-resuscitation treatment, potentially being misleading and not fully reflecting the severity of postcardiac arrest syndrome. Even if validated criteria are lacking, an extensive hemodynamic evaluation is useful to define a "benign" and a "malign" form of myocardial dysfunction and circulatory shock, potentially having treatment and prognostic implications. Cardiac output is frequently decreased after cardiac arrest, particularly in patients treated with target temperature management (TTM); however, it is not independently associated with outcome. Sinus bradycardia during TTM seems independently associated with survival and good neurological outcome, representing a promising prognostic indicator. Higher mean arterial pressure (MAP) seems to be associated with improved survival and cerebral function after cardiac arrest; however, two recent randomized clinical trials failed to replicate these results. Recommendations on hemodynamic optimization are relatively poor and are largely based on general principle of intensive care medicine.

Slow Heart Rate Within 72 Hours After Cardiac Arrest Is Associated with Good Neurologic Outcome in Out-of-Hospital Cardiac Arrest Survivors Who Undergo Targeted Temperature Management with 33°C

We aimed to verify whether slow heart rate (HR) is associated with neurologic outcome and the factors that can contribute to the development of bradycardia in out-of-hospital cardiac arrest (OHCA) survivors who underwent targeted temperature management (TTM). We extracted the data of comatose adult OHCA survivors who underwent TTM between October 2015 and December 2018 from the prospective multicenter registry. Data on HR recorded every 6 hours within 72 hours after return of spontaneous circulation and calculated minimal, mean, and maximal HR and time to the lowest HR were obtained. HR <50 bpm was defined as bradycardia. The primary outcome was a 6-month neurologic outcome based on Pittsburgh-Glasgow Cerebral Performance Category Scale. Of the 814 included patients, 508 (62.4%) had poor neurologic outcome and 197 (24.2%) had bradycardia. Bradycardia (odds ratio [OR], 0.574; 95% confidence interval [CI], 0.362-0.192), minimal HR (OR, 1.023; 95% CI, 1.008-1.037), and mean HR (OR, 1.016; 95% CI, 1.002-1.030) were independently associated with poor neurologic outcome, but not maximal HR and time to the lowest HR. Preexisting arrhythmia (OR, 2.067; 95% CI, 1.037-4.118), renal disease (OR, 2.028; 95% CI, 1.153-3.567), cardiac etiology (OR, 1.526; 95% CI, 1.045-2.228), downtime (OR, 0.985; 95% CI, 0.974-0.996), and serum lactate levels (OR, 0.936; 95% CI, 0.900-0.974) were independently associated with bradycardia. Bradycardia and decreased mean and minimal HR were independently associated with good neurologic outcomes. Bradycardia was associated with preexisting arrhythmia, renal disease, cardiac etiology, shorter downtime, and lower serum lactate level.

Sinus Bradycardia During Targeted Temperature Management: A Systematic Review and Meta-Analysis

The beneficial effect of sinus bradycardia during targeted temperature management (TTM) in cardiac arrest patients remains doubtful. We aimed to investigate the impact of sinus bradycardia on survival and neurological outcome. MEDLINE (PubMed), Cochrane, Google Scholar, and ClinicalTrials.gov databases were searched for studies reporting on comatose postcardiac arrest patients presenting sinus bradycardia during TTM. Outcomes were the 180-day survival and final neurologic function assessed by the Cerebral Performance Category scale. The effect size on study outcomes is presented as odds ratio (OR) with 95% confidence interval (CI). Two studies with 681 patients were included. Compared to no-sinus bradycardia group, in patients with sinus bradycardia below 50 bpm, a significant effect of sinus bradycardia on reduction of 180-day mortality was reported (OR = 0.42; 95% CI: 0.29-0.59). No heterogeneity was detected. Sinus bradycardia below 50 bpm during TTM may be protective and should be considered in comatose postcardiac arrest patients.

The impact of diastolic blood pressure values on the neurological outcome of cardiac arrest patients

AIM

Which haemodynamic variable is the best predictor of neurological outcome remains unclear. We investigated the association of several haemodynamic variables with neurological outcome in CA patients.

METHODS

Retrospective analysis of adult comatose survivors of CA admitted to the intensive care unit (ICU) of a University Hospital. Exclusion criteria were early death due to withdrawal of care, missing haemodynamic data and use of intra-aortic balloon pump or extracorporeal membrane oxygenation. We retrieved CA characteristics; lactate concentration and cardiovascular sequential organ failure assessment (cSOFA) score on admission; systolic (SAP), diastolic (DAP), mean arterial pressure (MAP), and the use of vasopressors and inotropic agents during the first 6 h of ICU stay. Unfavourable neurological outcome (UO) was defined as a 3-month cerebral performance category score of 3-5.

RESULTS

Among the 170 patients (median age 63 years, 67% male, 60% out-of-hospital CA), 106 (63%) had UO. Admission lactate was higher in patients with UO than in those with favourable neurological outcome (4.0[2.4-7.3] vs. 2.5[1.4-6.0] mEq/L; p = 0.003) as was the cSOFA (3 [1-4] vs. 2[0-3]; p = 0.007). The lowest DAP during the first 6 h after ICU admission was significantly lower in patients with unfavourable neurological outcome, notably in patients with high cSOFA scores. In multivariable analysis, high adrenaline doses and the lowest value of DAP during the first 6 h after ICU admission was significantly associated with unfavourable neurological outcome.

CONCLUSIONS

In CA patients admitted to the ICU, low DAP during the first 6 h is an independent predictor of unfavourable neurological outcome at 3 months.