Update on cardiac arrhythmias in the ICU

Identifying acute kidney injury subphenotypes using an outcome-driven deep-learning approach

OBJECTIVE

Acute kidney injury (AKI), a common condition on the intensive-care unit (ICU), is characterized by an abrupt decrease in kidney function within a few hours or days, leading to kidney failure or damage. Although AKI is associated with poor outcomes, current guidelines overlook the heterogeneity among patients with this condition. Identification of AKI subphenotypes could enable targeted interventions and a deeper understanding of the injury's pathophysiology. While previous approaches based on unsupervised representation learning have been used to identify AKI subphenotypes, these methods cannot assess time series or disease severity.

METHODS

In this study, we developed a data- and outcome-driven deep-learning (DL) approach to identify and analyze AKI subphenotypes with prognostic and therapeutic implications. Specifically, we developed a supervised long short-term memory (LSTM) autoencoder (AE) with the aim of extracting representation from time-series EHR data that were intricately correlated with mortality. Then, subphenotypes were identified via application of K-means.

RESULTS

In two publicly available datasets, three distinct clusters were identified, characterized by mortality rates of 11.3%, 17.3%, and 96.2% in one dataset and 4.6%, 12.1%, and 54.6% in the other. Further analysis demonstrated that AKI subphenotypes identified by our proposed approach were statistically significant on several clinical characteristics and outcomes.

CONCLUSION

In this study, our proposed approach could successfully cluster the AKI population in ICU settings into 3 distinct subphenotypes. Thus, such approach could potentially improve outcomes of AKI patients in the ICU, with better risk assessment and potentially better personalized treatment.

Outcome of life-threatening arrhythmias among patients presenting in an emergency setting at a tertiary hospital in Accra-Ghana

Background

Management of life-threatening arrhythmia can be incredibly challenging in advanced health systems. In sub-Saharan Africa (SSA), this is likely more challenging because of weak pre-hospital and in-hospital critical care systems. Little is known about life-threatening arrhythmia and their outcomes in SSA. The aim of this study was to examine the types and outcomes of arrhythmias among haemodynamically unstable patients presenting at a tertiary hospital in Accra-Ghana.

Method

This was a retrospective case series study conducted at the Korle-Bu Teaching Hospital (KBTH), Accra-Ghana. Medical records of patients who presented with or developed haemodynamically unstable arrhythmias within 24h of admission from January 2018 to December 2020 were reviewed. The demographic characteristics and clinical data including outcomes of patients were collected. Descriptive statistics were used and results presented in frequency tables.

Results

A total of 42 patients with life-threatening arrhythmias were included. Haemodynamically unstable tachyarrhythmias were the most common arrhythmias found among the patients (66.7%). Approximately 52% of patients had structural heart diseases whereas 26.2% had no apparent underlying cause or predisposing factor. Cardioversion (52.4%), commonly electrical (63.6%), and transvenous pacemaker implantation (23.8%) were the common initial interventions. The majority of the patients (88.1%) survived and were discharged home.

Conclusion

Tachyarrhythmias are the most common haemodynamically unstable arrhythmias seen among patients presenting emergently in a leading tertiary hospital in Ghana. A high survival rate was observed and cannot be extrapolated to other healthcare settings in sub-Saharan Africa with limited resources to manage these clinical entities.

Development and Internal Validation of a Nomogram to Predict Mortality During the ICU Stay of Thoracic Fracture Patients Without Neurological Compromise: An Analysis of the MIMIC-III Clinical Database

Background: This study aimed to develop and validate a nomogram for predicting mortality in patients with thoracic fractures without neurological compromise and hospitalized in the intensive care unit. Methods: A total of 298 patients from the Medical Information Mart for Intensive Care III (MIMIC-III) database were included in the study, and 35 clinical indicators were collected within 24 h of patient admission. Risk factors were identified using the least absolute shrinkage and selection operator (LASSO) regression. A multivariate logistic regression model was established, and a nomogram was constructed. Internal validation was performed by the 1,000 bootstrap samples; a receiver operating curve (ROC) was plotted, and the area under the curve (AUC), sensitivity, and specificity were calculated. In addition, the calibration of our model was evaluated by the calibration curve and Hosmer-Lemeshow goodness-of-fit test (HL test). A decision curve analysis (DCA) was performed, and the nomogram was compared with scoring systems commonly used during clinical practice to assess the net clinical benefit. Results: Indicators included in the nomogram were age, OASIS score, SAPS II score, respiratory rate, partial thromboplastin time (PTT), cardiac arrhythmias, and fluid-electrolyte disorders. The results showed that our model yielded satisfied diagnostic performance with an AUC value of 0.902 and 0.883 using the training set and on internal validation. The calibration curve and the Hosmer-Lemeshow goodness-of-fit (HL). The HL tests exhibited satisfactory concordance between predicted and actual outcomes (P = 0.648). The DCA showed a superior net clinical benefit of our model over previously reported scoring systems. Conclusion: In summary, we explored the incidence of mortality during the ICU stay of thoracic fracture patients without neurological compromise and developed a prediction model that facilitates clinical decision making. However, external validation will be needed in the future.

The Association of Early Electrocardiographic Abnormalities With Brain Injury Severity and Outcome in Severe Traumatic Brain Injury

The aim of this study was to evaluate the frequency of electrocardiographic (ECG) abnormalities in the acute phase of severe traumatic brain injury (TBI) and the association with brain injury severity and outcome. In contrast to neurovascular diseases, sparse information is available on this issue. Data of adult patients with severe TBI admitted to the Intensive Care Unit (ICU) for intracranial pressure monitoring of a level-1 trauma center from 2002 till 2018 were analyzed. Patients with a cardiac history were excluded. An ECG recording was obtained within 24 h after ICU admission. Admission brain computerized tomography (CT)-scans were categorized by Marshall-criteria (diffuse vs. mass lesions) and for location of traumatic lesions. CT-characteristics and maximum Therapy Intensity Level (TILmax) were used as indicators for brain injury severity. We analyzed data of 198 patients, mean (SD) age of 40 ± 19 years, median GCS score 3 [interquartile range (IQR) 3–6], and 105 patients (53%) had thoracic injury. In-hospital mortality was 30%, with sudden death by cardiac arrest in four patients. The incidence of ECG abnormalities was 88% comprising ventricular repolarization disorders (57%) mostly with ST-segment abnormalities, conduction disorders (45%) mostly with QTc-prolongation, and arrhythmias (38%) mostly of supraventricular origin. More cardiac arrhythmias were observed with increased grading of diffuse brain injury (p = 0.042) or in patients treated with hyperosmolar therapy (TILmax) (65%, p = 0.022). No association was found between ECG abnormalities and location of brain lesions nor with thoracic injury. Multivariate analysis with baseline outcome predictors showed that cardiac arrhythmias were not independently associated with in-hospital mortality (p = 0.097). Only hypotension (p = 0.029) and diffuse brain injury (p = 0.017) were associated with in-hospital mortality. In conclusion, a high incidence of ECG abnormalities was observed in patients with severe TBI in the acute phase after injury. No association between ECG abnormalities and location of brain lesions or presence of thoracic injury was present. Cardiac arrhythmias were indicative for brain injury severity but not independently associated with in-hospital mortality. Therefore, our findings likely suggest that ECG abnormalities should be considered as cardiac mimicry representing the secondary effect of traumatic brain injury allowing for a more rationale use of neuroprotective measures.

Atrial Arrhythmias in a Patient Presenting With Coronavirus Disease-2019 (COVID-19) Infection

The coronavirus disease-2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) that has significant potential cardiovascular implications for patients. These include myocarditis, acute coronary syndromes, cardiac arrhythmias, cardiomyopathies with heart failure and cardiogenic shock, and venous thromboembolic events. We describe a Caribbean-Black gentleman with COVID-19 infection presenting with atrial arrhythmias, namely, atrial flutter and atrial fibrillation, which resolved with rate and rhythm control strategies, and supportive care.

Severe sepsis and cardiac arrhythmias

Background

Although sepsis is a known risk factor for cardiac arrhythmias, data on incidence and outcomes of atrial and ventricular arrhythmias in severe sepsis is limited. The purpose of this study is to examine the association of severe sepsis with cardiac arrhythmias and their impact on outcome in this patient population.

Methods

We used hospital discharge data from the Nationwide Inpatient Sample (NIS) during the year 2012. All patients 18 years or older were included in the study. The International Classification of Diseases-Clinical Modification, 9th revision (ICD-9-CM) code was used to identify patients with discharge diagnosis of severe sepsis, atrial fibrillation (A Fib), atrial flutter (AFL), ventricular fibrillation (VF) arrest and non-ventricular fibrillation (non-VF) arrest. In order to study the association of arrhythmias with severe sepsis, two groups were defined: group a-with severe sepsis was compared to group b-without severe sepsis. Univariate and multivariate logistic regression methods were used to adjust for potential confounding factors and variables associated with cardiac arrhythmias were determined.

Results

A total of 30,712,524 NIS hospital discharges (weighted for national estimate) were included in our study, of which 1,756,965 (5.7%) had severe sepsis. On multivariate analysis, after adjusting for potential confounders, severe sepsis was associated with higher risk of A Fib (OR, 1.23; 95% CI, 1.21-1.24), AFL (OR, 1.34; 95% CI, 1.30-1.40), VF arrest (OR, 2.58; 95% CI, 2.38-2.79) (OR, 3.31; 95% CI, 3.07-3.57) and non-VF arrest (OR, 4.91; 95% CI, 4.74-5.07). In the severe sepsis group, cardiac arrhythmia was associated with higher in-hospital mortality (OR, 1.41; 95% CI, 1.37-1.45), length of stay (LOS) >75% quartile (OR, 1.50; 95% CI, 1.46-1.53) and total hospital charges >75% quartile (OR, 1.37; 95% CI, 1.34-1.41). Advanced age, male sex, ischemic heart disease, diabetes mellitus (DM), congestive heart failure (CHF), valvular heart disease, respiratory failure, mechanical ventilation and use of vasopressors were independently associated with cardiac arrhythmias.

Conclusions

Patients with severe sepsis are at high risk of atrial and life threatening ventricular arrhythmias. Despite adjustment for potential confounding factors, patients hospitalized with severe sepsis carry a significantly higher risk for cardiac arrest and increased mortality.

Gitelman syndrome: a rare life-threatening case of hypokalemic paralysis mimicking Guillain-Barré syndrome during pregnancy and review of the literature

In rare cases, patients with Gitelman syndrome may present with hypokalemic paralysis mimicking Guillain–Barré syndrome. The severity of resultant symptoms may be life‐threatening. Controversial drugs such as aldactone, amiloride, and eplerenone should be used in this situation despite the lack of safety data.

Incidence, Risk Factors and Outcomes of New Onset Supraventricular Arrhythmias in African American Patients with Severe Sepsis

PURPOSE

New onset supraventricular arrhythmias (SVA) are commonly reported in mixed intensive care settings. We sought to determine the incidence, risk factors and outcomes of new onset SVA in African American (AA) patients with severe sepsis admitted to medical intensive care unit (MICU).

METHODS

Patients admitted to MICU between January 2012 through December 2012 were studied. Patients with a previous history of arrhythmia or with new onset of ventricular arrhythmia were excluded. Data on risk factors, critical care interventions and outcomes were obtained.

RESULTS

One hundred and thirty-one patients were identified. New onset SVA occurred in 34 (26%) patients. Of those 34, 20 (59%) had atrial fibrillation (AF), 6 (18%) had atrial flutter and 8 (24%) had other forms of SVA. Compared with patients without SVA, patients with new onset SVA were older (69 ± 12 yrs vs 59 ± 13 yrs, P=.003), had congestive heart failure (47% vs 24%, P=.015) and dyslipidemia (41% vs 15%, P=.002). Additionally, they had a higher mean mortality prediction model (MPM II) score (65 ± 25 vs 49 ± 26, P=.001) and an increased incidence of respiratory failure (85% vs 55%, P=.001). Hospital mortality in patients with new onset SVA was 18 (53%) vs 30 (31%); P=.024; however, in a multivariate analysis, new onset SVA was associated with non-significantly increased odds (OR 2.58, 95% CI 0.86-8.05) for in-hospital mortality.

CONCLUSIONS

New onset SVA was prevalent in AA patients with severe sepsis and occurred more frequently with advanced age, increased severity of illness, congestive heart failure, and acute respiratory failure; it was associated with higher unadjusted in hospital mortality. However, after multiple adjustments, new onset SVA did not remain an independent predictor of mortality.

Cardiac Arrhythmias in a Septic ICU Population: A Review

Progressive cardiovascular deterioration plays a central role in the pathogenesis of multiple organ failure (MOF) caused by sepsis. Evidence of various cardiac arrhythmias in septic patients has been reported in many published studies. In the critically ill septic patients, compared to non-septic patients, new onset atrial fibrillation episodes are associated with high mortality rates and poor outcomes, amongst others being new episodes of stroke, heart failure and long vasopressor usage. The potential mechanisms of the development of new cardiac arrhythmias in sepsis are complex and poorly understood. Cardiac arrhythmias in critically ill septic patients are most likely to be an indicator of the severity of pre-existing critical illness.

Arrhythmias in the paediatric intensive care unit: a prospective study of the rates and predictors of arrhythmias in children without underlying cardiac disease

OBJECTIVE

Arrhythmias are common in patients admitted to the paediatric intensive care unit. We sought to identify the rates of occurrence and types of arrhythmias, and determine whether an arrhythmia was associated with illness severity and paediatric intensive care unit length of stay.

DESIGN

This is a prospective, observational study of all patients admitted to the paediatric intensive care unit at the Children's Hospital at Montefiore from March to June 2012. Patients with cardiac disease or admitted for the treatment of primary arrhythmias were excluded. Clinical and laboratory data were collected and telemetry was reviewed daily. Tachyarrhythmias were identified as supraventricular tachycardia, ventricular tachycardia, and arrhythmias causing haemodynamic compromise or for which an intervention was performed.

RESULTS

A total of 278 patients met the inclusion criteria and were analysed. There were 97 incidences of arrhythmia in 53 patients (19%) and six tachyarrhythmias (2%). The most common types of arrhythmias were junctional rhythm (38%), premature atrial contractions (24%), and premature ventricular contractions (22%). Tachyarrhythmias included three supraventricular tachycardia (50%) and three ventricular tachycardia (50%). Of the six tachyarrhythmias, four were related to placement or migration of central venous lines and two occurred during aminophylline infusion. Patients with an arrhythmia had longer duration of mechanical ventilation and paediatric intensive care unit stay (p<0.001). In multivariate analysis, central venous lines (odds ratio 3.1; 95% confidence interval 1.3-7.2, p=0.009) and aminophylline use (odds ratio 5.1; 95% confidence interval 1.7-14.9, p=0.003) were independent predictors for arrhythmias.

CONCLUSIONS

Arrhythmias were common in paediatric intensive care unit patients (19%), although tachyarrhythmias occurred rarely (2%). Central venous lines and use of aminophylline were identified as two clinical factors that may be associated with development of an arrhythmia.

Incidence and Predictors of New-Onset Atrial Fibrillation in Septic Shock Patients in a Medical ICU: Data from 7-Day Holter ECG Monitoring

Purpose

We investigated incidence, risk factors for new-onset atrial fibrillation (NAF), and prognostic impact during septic shock in medical Intensive Care Unit (ICU) patients.

Methods

Prospective, observational study in a university hospital. Consecutive patients from 03/2011 to 05/2013 with septic shock were eligible. Exclusion criteria were age <18 years, history of AF, transfer with prior septic shock. Included patients were equipped with long-duration (7 days) Holter ECG monitoring. NAF was defined as an AF episode lasting >30 seconds. Patient characteristics, infection criteria, cardiovascular parameters, severity of illness, support therapies were recorded.

Results

Among 66 patients, 29(44%) developed NAF; 10 (34%) would not have been diagnosed without Holter ECG monitoring. NAF patients were older, with more markers of heart failure (troponin and NT-pro-BNP), lower left ventricular ejection fraction (LVEF), longer QRS duration and more nonsustained supra ventricular arrhythmias (<30s) on day 1 than patients who maintained sinus rhythm. By multivariate analysis, age (OR: 1.06; p = 0.01) and LVEF<45% (OR: 13.01, p = 0.03) were associated with NAF. NAF did not predict 28 or 90 day mortality.

Conclusions

NAF is common, especially in older patients, and is associated with low ejection fraction. We did not find NAF to be independently associated with higher mortality.

New-onset atrial fibrillation in sepsis is associated with increased morbidity and mortality

Background

The development of new-onset atrial fibrillation in sepsis has been associated with adverse outcomes.

Methods

A systematic literature search was conducted to retrieve articles that investigated the association of new-onset atrial fibrillation in patients diagnosed with sepsis. The primary outcome of interest was the pooled risk ratio (RR) of in-hospital mortality in patients with new-onset atrial fibrillation and sepsis.

Results

Six studies included 3100 patients with new-onset atrial fibrillation in sepsis and 36,900 patients without new-onset atrial fibrillation in sepsis. The pooled RR for in-hospital mortality was 1.45 (95 % CI 1.32–1.60, p < 0.00001, I^2 =24 %). New-onset atrial fibrillation was also associated with increased ICU mortality, ICU and in-hospital length of stay and stroke. New-onset atrial fibrillation occurred more in the elderly, those with a prior history of cardiovascular and respiratory disease, and those with increased severity of illness.

Conclusion

Prospective randomised trials are needed to clarify the significance of new-onset atrial fibrillation in sepsis, optimal treatment strategies for these patients, and the benefit of systemic anticoagulation. Physicians should be aware that new-onset atrial fibrillation in sepsis is not merely an observed temporary arrhythmia but a marker of poor prognosis and should be managed accordingly.

Incidence, risk factors and outcomes of new-onset atrial fibrillation in patients with sepsis: a systematic review

Introduction

Critically ill patients with sepsis are prone to develop cardiac dysrhythmias, most commonly atrial fibrillation (AF). Systemic inflammation, circulating stress hormones, autonomic dysfunction, and volume shifts are all possible triggers for AF in this setting. We conducted a systematic review to describe the incidence, risk factors and outcomes of new-onset AF in patients with sepsis.

Methods

MEDLINE, EMBASE and Web Of Science were searched for studies reporting the incidence of new-onset AF, atrial flutter or supraventricular tachycardia in patients with sepsis admitted to an intensive care unit, excluding studies that primarily focused on postcardiotomy patients. Studies were assessed for methodological quality using the GRADE system. Risk factors were considered to have a high level of evidence if they were reported in ≥2 studies using multivariable analyses at a P value <0.05. Subsequently, the strength of association was classified as strong, moderate or weak, based on the reported odds ratios.

Results

Eleven studies were included. Overall quality was low to moderate. The weighted mean incidence of new-onset AF was 8% (range 0 to 14%), 10% (4 to 23%) and 23% (6 to 46%) in critically ill patients with sepsis, severe sepsis and septic shock, respectively. Independent risk factors with a high level of evidence included advanced age (weak strength of association), white race (moderate association), presence of a respiratory tract infection (weak association), organ failure (moderate association), and pulmonary artery catheter use (moderate association). Protective factors were a history of diabetes mellitus (weak association) and the presence of a urinary tract infection (weak association). New-onset AF was associated with increased short-term mortality in five studies (crude relative effect estimates ranging from 1.96 to 3.32; adjusted effects 1.07 to 3.28). Three studies reported a significantly increased length of stay in the ICU (weighted mean difference 9 days, range 5 to 13 days), whereas an increased risk of ischemic stroke was reported in the single study that looked at this outcome.

Conclusions

New-onset AF is a common consequence of sepsis and is independently associated with poor outcome. Early risk stratification of patients may allow for pharmacological interventions to prevent this complication.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0688-5) contains supplementary material, which is available to authorized users.

Association between Hypophosphatemia and Cardiac Arrhythmias in the Early Stage of Sepsis: Could Phosphorus Replacement Treatment Reduce the Incidence of Arrhythmias?

It is well known that new-onset arrhythmias are common in septic patients. It is thought that hypophosphatemia in the early stages of sepsis may contribute to the development of new arrhythmias. In this study, we hypothesized that intravenous (IV) phosphorus replacement may reduce the incidence of arrhythmias in critically ill patients. 34 adult septic patients with hypophosphatemia admitted to the general intensive care unit were treated with IV phosphorus replacement per ICU protocol, and the incidence of new arrhythmias were compared with 16 patients from previously published data. IV phosphorus replacement was associated with a significantly reduced incidence of arrhythmias (38% vs. 63%, p=0.04). There were no differences in observed mortality between subgroups, which may be due to the small sample size. This study demonstrated that IV phosphorus replacement might be effective in reducing the incidence of new arrhythmias in septic patients.

Optimizing drug therapy in the surgical intensive care unit

This article provides a review of commonly prescribed medications in the surgical ICU, focusing on sedatives, antipsychotics, neuromuscular blocking agents, cardiovascular agents, anticoagulants, and antibiotics. A brief overview of pharmacology is followed by practical considerations to aid prescribers in selecting the best therapy within a given category of drugs to optimize patient outcomes.

Contemporary epidemiology and prognosis of septic shock in infective endocarditis

AIMS

The prognosis of patients with infective endocarditis (IE) remains poor despite the great advances in the last decades. One of the factors closely related to mortality is the development of septic shock (SS). The aim of our study was to describe the profile of patients with IE complicated with SS, and to identify prognostic factors of new-onset SS during hospitalization.

METHODS AND RESULTS

We conducted a prospective study including 894 episodes of IE diagnosed at three tertiary centres. A backward logistic regression analysis was undertaken to determine prognostic factors associated with SS development. Multivariable analysis identified the following as predictive of SS development: diabetes mellitus [odds ratio (OR) 2.06; confidence interval (CI) 1.16-3.68], Staphylococcus aureus infection (OR: 2.97; CI: 1.72-5.15), acute renal insufficiency (OR: 3.22; CI: 1.28-8.07), supraventricular tachycardia (OR: 3.29; CI: 1.14-9.44), vegetation size ≥15 mm (OR: 1.21; CI: 0.65-2.25), and signs of persistent infection (OR: 9.8; CI: 5.48-17.52). Risk of SS development could be stratified when combining the first five variables: one variable present: 3.8% (CI: 2-7%); two variables present: 6.3% (CI: 3.2-12.1%); three variables present: 14.6% (CI: 6.8-27.6%); four variables present: 29.1% (CI: 11.7-56.1%); and five variables present: 45.4% (95% CI: 17.5-76.6%). When adding signs of persistent infection, the risk dramatically increased, reaching 85.7% (95% CI: 61.2-95.9%) of risk.

CONCLUSIONS

In patients with IE, the presence of diabetes, acute renal insufficiency, Staphylococcus aureus infection, supraventricular tachycardia, vegetation size ≥15 mm, and signs of persistent infection are associated with the development of SS.

Incidence and Prognosis of Atrial Fibrillation in Patients With Sepsis

Background

Although the mortality rate among patients with sepsis is declining, the incidence of both sepsis and sepsis-related deaths is increasing, likely due to its presence in a growing elderly population. As atrial fibrillation is more common in the elderly, we hypothesize that its presence will be associated with greater mortality among patients with sepsis.

Methods

The Medical Intensive Care Unit (MICU) database of a large tertiary care medical center was queried for sepsis-related codes and atrial fibrillation.

Results

Atrial fibrillation was associated with older age and a higher mortality in this series of patients with sepsis.

Conclusions

Whether atrial fibrillation is a marker of disease severity or contributes to mortality is uncertain. Further studies are necessary to determine optimal management.

Significance of new-onset prolonged sinus tachycardia in a medical intensive care unit: a prospective observational study

OBJECTIVE

Few data are available on sinus tachycardia among medical intensive care unit (ICU) patients. We investigated new critical illnesses related to new-onset prolonged sinus tachycardia (NOPST) and the relationship of NOPST with ICU mortality.

METHODS

The heart rate (HR) of all enrolled patients was monitored hourly over a 12-month period, and NOPST was defined as sinus tachycardia (>100 beats/min) with an increase in HR of more than 20% from the baseline value lasting longer than 6 hours.

RESULTS

Among the 522 patients enrolled, the average mean HR was 96.1 ± 18.4 beats/min. Fifty-two (10.0%) patients met the criteria for NOPST; pneumonia, delirium, septic shock, acute respiratory distress syndrome, catheter-related infections, and mechanical ventilator-related problems were related to the occurrence of NOPST. The ICU mortality rate in patients with a NOPST duration of more than 72 hours was higher compared with other patients with NOPST (60.0% vs 18.5%; P = .002). A high daily mean HR rather than NOPST was a significant predictor of ICU mortality (odds ratio, 1.415; 95% confidence interval, 1.177-1.700).

CONCLUSIONS

Although NOPST was not associated with ICU mortality, it indicates the presence of new critical events in the medical ICU setting.

Induction of heat shock proteins prevents the arrhythmogenic substrate for atrial fibrillation

Atrial fibrillation (AF) is the commonest arrhythmia. Studies have shown that atrial tachypacing (artificial persistent AF) causes electrical remodelling. This is characterised by the shortening of the atrial effective refractory period (ERP), in which reduction in L-type Ca(2+) channel current plays an essential part. Atrial fibrosis, a feature of structural remodelling, is induced by continuous infusion of angiotensin II, and has been associated with conduction delay in atria, which promotes AF. Acute atrial ischaemia, frequently observed during development of acute coronary syndrome, has been associated with atrial conduction heterogeneity, which also promotes AF. Induction of heat shock proteins (Hsp72 and Hsp27) by hyperthermia and/or geranylgeranylacetone has demonstrated to protect the heart against such atrial remodelling. The potent protective role of Hsp72 and Hsp27 against clinical AF in patients who underwent open heart surgery has been shown. Taken together, interventions that induce heat shock responses (including induction of Hsp72 and Hsp27) may prevent newly developed AF and delay the progression of paroxysmal AF to persistent AF.