Body Temperature – A Marker of Infarct Size in the Era of Early Reperfusion

Triage body temperature and its influence on patients with acute myocardial infarction

BACKGROUND

Fever can occur after acute myocardial infarction (MI). The influence of body temperature (BT) after hospital arrival on patients with acute MI has rarely been investigated.

METHODS

Patients who were diagnosed with acute MI in the emergency department (ED) of a tertiary teaching hospital between 1 January 2020 and 31 December 2020 were enrolled. Based on the tympanic temperature obtained at the ED triage, patients were categorized into normothermic (35.5°C-37.5°C), hypothermic (< 35.5°C), or hyperthermic (> 37.5°C) groups. The primary outcome was in-hospital cardiac arrest (IHCA), while the secondary outcomes were adverse events. Statistical significance was set at p < 0.05.

RESULTS

There were 440 enrollees; significant differences were found among the normothermic (n = 369, 83.9%), hypothermic (n = 27, 6.1%), and hyperthermic (n = 44, 10.0%) groups in the triage respiratory rate (median [IQR]) (20.0 [4.0] cycles/min versus 20.0 [4.0] versus 20.0 [7.5], p = 0.009), triage heart rate (88.0 [29.0] beats/min versus 82.0 [28.0] versus 102.5 [30.5], p < 0.001), presence of ST-elevation MI (42.0% versus 66.7% versus 31.8%, p = 0.014), need for cardiac catheterization (87.3% versus 85.2% versus 72.7%, p = 0.034), initial troponin T level (165.9 [565.2] ng/L versus 49.1 [202.0] versus 318.8 [2002.0], p = 0.002), peak troponin T level (343.8 [1405.9] ng/L versus 218.7 [2318.2] versus 832.0 [2640.8], p = 0.003), length of ICU stay (2.0 [3.0] days versus 3.0 [8.0] versus 3.0 [9.5], p = 0.006), length of hospital stay (4.0 [4.5] days versus 6.0 [15.0] versus 10.5 [10.8], p < 0.001), and infection during hospitalization (19.8% versus 29.6% versus 63.6%, p < 0.001) but not in IHCA (7.6% versus 14.8% versus 11.4%, p = 0.323) or any adverse events (50.9% versus 48.1% versus 63.6%, p = 0.258). Multivariable analysis showed no significant association of triage BT with IHCA or any major complication.

CONCLUSION

Triage BT did not show a significant association with IHCA or adverse events in patients with acute MI. However, triage BT could be associated with different clinical presentations and should warrant further investigation.

Inflammation in ST- elevation myocardial infarction: risk factors, patterns of presentation and association with clinical picture and outcome, an observational study conducted at the Institute of Cardiology-National Hospital of Sri Lanka

Background

Inflammation in myocardial infarction has a complex immunogenic origin and is suspected to be closely involved in its aetio-pathogenesis as well as outcome. In this study the objective was to further elucidate the clinical correlations of inflammation using clinical parameters and basic inflammatory markers and how it correlates with patient risk parameters, imaging findings and outcome.

Methods

An observational descriptive cross sectional study was carried out at the Institute of Cardiology, National Hospital of Sri Lanka, where consenting patients presenting for further management of ST- elevation myocardial infarction were recruited. Venous blood samples were collected on admission to assess C-reactive protein levels and on a timed manner to asses Troponin I levels as well as on subsequent days to performs whole blood analysis. Patients underwent 6 hourly axillary temperature assessment. All patients underwent 2D transthoracic echocardiographic analysis via biplane Simpson’s method to ascertain ejection fraction as well.

Results

Eighty eight subjects were recruited into the study. Fever was noted in 20.5% (n = 18). Fever was usually intermittent and seen commonly between day 1 and 3 post-acute myocardial infarction. Haematological abnormalities indicative of inflammation were also observed as whole blood analysis demonstrated predominant leukocytosis and elevated C-reactive protein levels. Significant correlation was noted between presence of leukocytosis (P = 0.033) and fever as well as with the presence of diabetes mellitus (P = 0.005). Development of acute heart failure also showed significant correlation with leukocytosis (P = 0.002). Correlation was also observed between LV dysfunction and elevated C-reactive protein and Troponin I levels with P values of P = 0.023 and P = 0.011 (P < 0.05) respectively.

Conclusions

Inflammation is appreciated following acute myocardial infarction. Biochemical evidence of inflammation is commonly seen. Clinical manifestation as fever however is seen less often. Patient factors correlate poorly with inflammation but diabetes mellitus may have a contributory role. Whole blood analysis derangement is a simple test that correlates well with inflammation as well as presence of fever and development of heart failure. Inflammation also correlated with left ventricular dysfunction and may thus have an impact on clinical morbidity and mortality. Delineating associates of inflammation will hopefully help improve therapy of myocardial infarction.

Clinical Significance of Postinfarct Fever in ST-Segment Elevation Myocardial Infarction: A Cardiac Magnetic Resonance Imaging Study

BACKGROUND

Little is known about causality and pathological mechanism underlying association of postinfarct fever with myocardial injury in patients with ST-segment elevation myocardial infarction.

METHODS AND RESULTS

In 276 patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction, cardiac magnetic resonance imaging was performed a median of 3.4 days after the index procedure. Forty-five patients had postinfarct fever (peak body temperature within 4 days after primary percutaneous coronary intervention ≥37.7°C; Fever group) whereas 231 did not (no-Fever group). Primary outcome was myocardial infarct size as assessed by cardiac magnetic resonance imaging. Secondary outcomes were extent of area at risk, myocardial salvage index, and microvascular obstruction area. In cardiac magnetic resonance imaging analysis, myocardial infarct size (25.6% [19.7-32.4] in the Fever group versus 17.2% [11.8-25.4] in the no-Fever group; P<0.01), extent of area at risk (43.7% [31.9-54.9] versus 35.3% [24.0-43.7]; P<0.01), and microvascular obstruction area (4.4% [0.0-13.2] versus 1.2% [0.0-5.1]; P=0.02) were greater in the Fever group than in the no-Fever group. Myocardial salvage index tended to be lower in the Fever group compared to the no-Fever group (37.7 [28.5-56.1] versus 47.0 [34.1-56.8]; P=0.13). In multivariate analysis, postinfarct fever was associated with larger myocardial infarct (odds ratio, 3.48; 95% CI, 1.71-7.07; P<0.01) and lower MSI (odds ratio, 2.10; 95% CI, 1.01-4.08; P=0.03).

CONCLUSIONS

Postinfarct fever could predict advanced myocardial injury and less salvaged myocardium in ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention.

How a GNSS Receiver Is Held May Affect Static Horizontal Position Accuracy

The static horizontal position accuracy of a mapping-grade GNSS receiver was tested in two forest types over two seasons, and subsequently was tested in one forest type against open sky conditions in the winter season. The main objective was to determine whether the holding position during data collection would result in significantly different static horizontal position accuracy. Additionally, we wanted to determine whether the time of year (season), forest type, or environmental variables had an influence on accuracy. In general, the F4Devices Flint GNSS receiver was found to have mean static horizontal position accuracy levels within the ranges typically expected for this general type of receiver (3 to 5 m) when differential correction was not employed. When used under forest cover, in some cases the GNSS receiver provided a higher level of static horizontal position accuracy when held vertically, as opposed to held at an angle or horizontally (the more natural positions), perhaps due to the orientation of the antenna within the receiver, or in part due to multipath or the inability to use certain satellite signals. Therefore, due to the fact that numerous variables may affect static horizontal position accuracy, we only conclude that there is weak to moderate evidence that the results of holding position are significant. Statistical test results also suggest that the season of data collection had no significant effect on static horizontal position accuracy, and results suggest that atmospheric variables had weak correlation with horizontal position accuracy. Forest type was found to have a significant effect on static horizontal position accuracy in one aspect of one test, yet otherwise there was little evidence that forest type affected horizontal position accuracy. Since the holding position was found in some cases to be significant with regard to the static horizontal position accuracy of positions collected in forests, it may be beneficial to have an understanding of antenna positioning within the receiver to achieve the greatest accuracy during data collection.

Fever after primary percutaneous coronary intervention in ST-segment elevation myocardial infarction is associated with adverse outcomes

BACKGROUND

Fever is a common finding after primary percutaneous coronary intervention (PPCI) in patients with ST-segment elevation myocardial infarction (STEMI). However, its prognostic value is not validated yet.

OBJECTIVES

This study sought to evaluate the impact of fever after PPCI in STEMI on adverse clinical outcomes.

METHODS

Five hundred fourteen consecutive patients who underwent PPCI due to STEMI were enrolled. Body temperature (BT) was checked every 6 h for 5 days after PPCI. Patients were divided into two groups according to the highest quartile of peak BT; peak BT≤37.6 °C (control group) and peak BT>37.6 °C (fever group). Rates of 1-year major adverse cardiovascular events (MACE; death, myocardial infarction, any revascularization) were compared.

RESULTS

The prevalence of fever group (peak BT>37.6 °C) was 24.7% (127/514). White blood cell count, highly sensitive C-reactive protein and serum cardiac troponin I level were higher in fever group than control group (12,162±4199/μL vs. 10,614±3773/μL, p<0.001; 22.9±49.4 mg/L vs. 7.4±2.5 mg/L, p=0.001, 16.7±36.9 ng/dl vs. 8.70±26.2 ng/dl, p=0.027, respectively). The frequency of a history of previous myocardial infarction and left ventricular ejection fraction was lower in fever group (0.0% vs. 4.7%, p=0.010; 47±8 % vs. 49±9 %, p=0.002, respectively). There was no significant difference in angiographic characteristics between 2 groups. 1-year MACE rates were higher in fever group (11.0% vs. 4.7%, p=0.010). Multivariate analysis revealed fever (OR 2.358, 95% CI 1.113-4.998, p=0.025), diabetes mellitus as risk factor (2.227, 1.031-4.812, 0.042), and left anterior descending artery as infarct related artery (2.443, 1.114-5.361, 0.026) as independent predictors for 1-year MACE.

CONCLUSIONS

Fever after PPCI in patients with STEMI is frequently developed and it can predict adverse clinical outcome.

Post-hypothermia fever is associated with increased mortality after out-of-hospital cardiac arrest

OBJECTIVE

Post-cardiac arrest fever has been associated with adverse outcome before implementation of therapeutic hypothermia (TH), however the prognostic implications of post-hypothermia fever (PHF) in the era of modern post-resuscitation care including TH has not been thoroughly investigated. The aim of the study was to assess the prognostic implication of PHF in a large consecutive cohort of comatose survivors after out-of-hospital cardiac arrest (OHCA) treated with TH.

METHODS

In the period 2004-2010, a total of 270 patients resuscitated after OHCA and surviving a 24-h protocol of TH with a target temperature of 32-34°C were included. The population was stratified in two groups by median peak temperature (≥38.5°C) within 36h after rewarming: PHF and no-PHF. Primary endpoint was 30-days mortality and secondary endpoint was neurological outcome assessed by Cerebral Performance Category (CPC) at hospital discharge.

RESULTS

PHF (≥38.5°C) was associated with a 36% 30-days mortality rate compared to 22% in patients without PHF, plog-rank=0.02, corresponding to an adjusted hazard rate (HR) of 1.8 (95% CI: 1.1-2.7), p=0.02). The maximum temperature (HR=2.0 per °C above 36.5°C (95% CI: 1.4-3.0), p=0.0005) and the duration of PHF (HR=1.6 per 8h (95% CI: 1.3-2.0), p<0.0001) were also independent predictors of 30-days mortality in multivariable models. Good neurological outcome (CPC1-2) versus unfavourable outcome (CPC3-5) at hospital discharge was found in 61% vs. 39% in the PHF group compared to 75% vs. 25% in the No PHF group, p=0.02.

CONCLUSIONS

Post-hypothermia fever ≥38.5°C is associated with increased 30-days mortality, even after controlling for potential confounding factors. Avoidance of PHF as a therapeutic target should be evaluated in prospective randomized trials.

Serious infection after acute myocardial infarction: incidence, clinical features, and outcomes

OBJECTIVES

The aim of this study was to address the knowledge gap using the APEX-AMI (Assessment of Pexelizumab in Acute Myocardial Infarction) trial database. We also assessed the association between serious infections and 90-day death or death/myocardial infarction (MI).

BACKGROUND

Little is known about the incidence, location, etiological organisms, and outcomes of infection in patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention.

METHODS

We analyzed data from 5,745 STEMI patients enrolled in the APEX-AMI trial. Detailed information on infection was collected for all patients. We described characteristics of patients according to infection and details of infection. Cox proportional hazards models were used to assess 90-day outcomes among patients with and without infections after adjusting for associated clinical variables and with infection as a time-dependent covariate.

RESULTS

Overall, 138 patients developed a serious infection (2.4%), most of whom presented with a single-site infection. The median (25th, 75th percentile) time until diagnosis of infection was 3 (1, 6) days. The most commonly identified organism was Staphylococcus aureus, and the main location of infection was the bloodstream. These patients had more comorbidities and lower procedural success at index percutaneous coronary intervention than those without infections. Serious infection was associated with significantly higher rates of 90-day death (adjusted hazard ratio: 5.6; 95% confidence interval: 3.8 to 8.4) and death or MI (adjusted hazard ratio: 4.9; 95% confidence interval: 3.4 to 7.1).

CONCLUSIONS

Infections complicating the course of patients with STEMI were uncommon but associated with markedly worse 90-day clinical outcomes. Mechanisms for early identification of these high-risk patients as well as design of strategies to reduce their risk of infection are warranted.

The diagnostic role of procalcitonin and other biomarkers in discriminating infectious from non-infectious fever

Fever is not only observed in the course of a bacterial or viral infection, but can be a symptom of, for instance, auto-immune, malignant or thromboembolic disease. Determining the etiology of fever in a fast and reliable way is of pivotal importance, as different causes of fever may ask for different therapies. Neither clinical signs and symptoms, nor traditional biomarkers, such as CRP, leukocytes and ESR have sufficient sensitivity and specificity to guide treatment decisions. In this review we focus on the value of traditional and newer biomarkers in non-infectious febrile diseases. Procalcitonin (PCT) seems to be the most helpful laboratory marker for the differentiation of causes of fever, particularly in autoimmune, autoinflammatory and malignant diseases.

Body temperature changes are associated with outcomes following in-hospital cardiac arrest and return of spontaneous circulation

INTRODUCTION

Spontaneous changes in body temperature after return of circulation (ROSC) from cardiac arrest are common, but the association of these changes with outcomes in hospitalized patients who survive to 24h post-ROSC is not known. We tested the hypothesis that adults who experience temperature lability in the first 24h have worse outcomes compared with those who maintain normothermia.

MATERIALS AND METHODS

A prospective observational study from a multicenter registry of cardiac arrests (National Registry of Cardiopulmonary Resuscitation) from 355 US and Canadian hospitals. 14,729 adults with return of circulation from a pulseless cardiac arrest. We excluded those who died or were discharged before 24h post-event, those made Do-Not-Resuscitate (DNR) within 24h of event, those that had a preceding trauma, and those with multiple cardiac arrests. Finally, we included only subjects that had both a lowest (T(min)) and highest (T(max)) body temperature value recorded during the first 24-h after ROSC, resulting in a study sample of 3426 patients.

RESULTS

After adjustment for potential covariates, there was a lower odds of survival in those having an episode of hypothermia (adjusted odds ratio [OR], 0.62; 95% confidence interval [CI], 0.48-0.80), those having an episode of hyperthermia (OR, 0.67; 95% CI, 0.48-0.80), and those having an episode of both (OR, 0.59; 95% CI, 0.39-0.91). Among those who survived to discharge, there was also a lower odds of favorable neurologic performance in those who had an episode of hyperthermia (OR, 0.71; 95% CI, 0.51-0.98).

CONCLUSIONS

Episodes of temperature lability following in-hospital resuscitation from cardiac arrest are associated with lower odds of surviving to discharge. Hyperthermia is also associated with fewer patients leaving the hospital with favorable neurologic performance. Further studies should identify whether therapeutic control over changes in body temperature after in-hospital cardiac arrest improves outcomes.