Increased Body Temperature After Reperfused Acute Myocardial Infarction Is Associated With Adverse Left Ventricular Remodeling

Association of body temperature and mortality in critically ill patients: an observational study using two large databases

BACKGROUND

Body temperature (BT) is routinely measured and can be controlled in critical care settings. BT can impact patient outcome, but the relationship between BT and mortality has not been well-established.

METHODS

A retrospective cohort study was conducted based on the MIMIC-IV (N = 43,537) and eICU (N = 75,184) datasets. The primary outcome and exposure variables were hospital mortality and first 48-h median BT, respectively. Generalized additive models were used to model the associations between exposures and outcomes, while adjusting for patient age, sex, APS-III, SOFA, and Charlson comorbidity scores, temperature gap, as well as ventilation, vasopressor, steroids, and dialysis usage. We conducted subgroup analysis according to ICU setting, diagnoses, and demographics.

RESULTS

Optimal BT was 37 °C for the general ICU and subgroup populations. A 10% increase in the proportion of time that BT was within the 36-38 °C range was associated with reduced hospital mortality risk in both MIMIC-IV (OR 0.91; 95% CI 0.90-0.93) and eICU (OR 0.86; 95% CI 0.85-0.87). On the other hand, a 10% increase in the proportion of time when BT < 36 °C was associated with increased mortality risk in both MIMIC-IV (OR 1.08; 95% CI 1.06-1.10) and eICU (OR 1.18; 95% CI 1.16-1.19). Similarly, a 10% increase in the proportion of time when BT > 38 °C was associated with increased mortality risk in both MIMIC-IV (OR 1.09; 95% CI 1.07-1.12) and eICU (OR 1.09; 95% CI 1.08-1.11). All patient subgroups tested consistently showed an optimal temperature within the 36-38 °C range.

CONCLUSIONS

A BT of 37 °C is associated with the lowest mortality risk among ICU patients. Further studies to explore the causal relationship between the optimal BT and mortality should be conducted and may help with establishing guidelines for active BT management in critical care settings.

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.

Braun-Dullaeus R. Cardiogenic Causes of Fever

BACKGROUND

Persistent fever of unknown cause is only rarely of cardiac origin, but heart disease must be considered in the differential diagnosis. Aside from endocarditis, pericarditis and various other conditions may be responsible.

METHODS

This review is based on pertinent articles retrieved by a selective search in PubMed and Google Scholar employing the term "fever" in combination with "myocardial infarction," "pericarditis," "endocarditis," and "postcardiac injury," with additional consideration of current cardiological guidelines.

RESULTS

Endocarditis is associated with fever in 90% of cases, but 25-50% of patients also develop high body temperatures after acute myocardial infarction. In pericarditis, a temperature above 38°C indicates a poorer prognosis; if accompanied by other warning signs, it is an indication for hospitalization and pericardiocentesis. Fever can arise after cardiac surgical procedures as a manifestation of post - cardiotomy syndrome, a special type of perimyocarditis. There may be a latency period of up to 3 months.

CONCLUSION

Fever can have both infectious and non-infectious cardiac causes. Its interpretation depends on the clinical context. The evidence base for treatment is sparse, and controlled trials are needed.

Prolonged Fever After ST-Segment Elevation Myocardial Infarction and Long-Term Cardiac Outcomes

Background

The biphasic inflammation after ST‐segment elevation myocardial infarction (STEMI) plays an important role in myocardial healing and progression of systemic atherosclerosis. The purpose of this study is to investigate the impact of fever during the first and second phases of post‐STEMI inflammation on long‐term cardiac outcomes.

Methods and Results

A total of 550 patients with STEMI were enrolled in this study. Axillary body temperature (BT) was measured and maximum BTs were determined for the first (within 3 days: max‐BT_1–3d) and second (from 4 to 10 days after admission: max‐BT_4–10d) phases, respectively. Patients were followed for cardiac events (cardiovascular death, acute coronary syndrome, and rehospitalization for heart failure) for a median 5.3 years. During the follow‐up period, 80 patients experienced cardiac events. A high max‐BT_4–10d was strongly associated with long‐term cardiac events (hazard ratio, 95% CI) for a 1°C increase in the max‐BT_4–10d: 2.834 (2.017–3.828), P<0.0001, whereas the max‐BT_1–3d was not associated with cardiac events (1.136 [0.731–1.742], P=0.57). Even after adjustment for coronary risk factors, estimated glomerular filtration rate, infarct size, pericardial effusion, and medications on discharge, fever during the second phase (max‐BT_4–10d ≥37.1°C) was significantly associated with future cardiac events (hazard ratio [95% CI] 2.900 [1.710–5.143], P<0.0001).

Conclusions

Fever during the second phase but not the first phase of post‐STEMI inflammation was a strong associated factor with worse long‐term cardiac outcomes in patients after STEMI, suggesting the need to consider the optimal timing for anti‐inflammatory strategies after STEMI.

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.

Integrative genomics identifies 7p11.2 as a novel locus for fever and clinical stress response in humans

Fever predicts clinical outcomes in sepsis, trauma and during cardiovascular stress, yet the genetic determinants are poorly understood. We used an integrative genomics approach to identify novel genomic determinants of the febrile response to experimental endotoxemia. We highlight multiple integrated lines of evidence establishing the clinical relevance of this novel fever locus. Through genome-wide association study (GWAS) of evoked endotoxemia (lipopolysaccharide (LPS) 1 ng/kg IV) in healthy subjects of European ancestry we discovered a locus on chr7p11.2 significantly associated with the peak febrile response to LPS (top single nucleotide polymorphism (SNP) rs7805622, P = 2.4 × 10(-12)), as well as with temperature fluctuation over time. We replicated this association in a smaller independent LPS study (rs7805622, P = 0.03). In clinical translation, this locus was also associated with temperature and mortality in critically ill patients with trauma or severe sepsis. The top GWAS SNPs are not located within protein-coding genes, but have significant cis-expression quantitative trait loci (eQTL) associations with expression of a cluster of genes ∼400 kb upstream, several of which (SUMF2, CCT6A, GBAS) are regulated by LPS in vivo in blood cells. LPS- and cold-treatment of adipose stromal cells in vitro suggest genotype-specific modulation of eQTL candidate genes (PSPH). Several eQTL genes were up-regulated in brown and white adipose following cold exposure in mice, highlighting a potential role in thermogenesis. Thus, through genomic interrogation of experimental endotoxemia, we identified and replicated a novel fever locus on chr7p11.2 that modulates clinical responses in trauma and sepsis, and highlight integrated in vivo and in vitro evidence for possible novel cis candidate genes conserved across human and mouse.

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.

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 small chill: mild hypothermia for cardioprotection?

Reducing the heart's temperature by 2-5°C is a potent cardioprotective treatment in animal models of coronary artery occlusion. The anti-infarct benefit depends upon the target temperature and the time at which cooling is instituted. Protection primarily results from cooling during the ischaemic period, whereas cooling during reperfusion or beyond offers little protection. In animal studies, protection is proportional to both the depth and duration of cooling. An optimal cooling protocol must appreciably shorten the normothermic ischaemic time to effectively salvage myocardium. Patients presenting with acute myocardial infarction could be candidates for mild hypothermia since the current door-to-balloon time is typically 90 min. But they would have to be cooled quickly shortly after their arrival. Several strategies have been proposed for ultra-fast cooling, but most like liquid ventilation and pericardial perfusion are too invasive. More feasible strategies might include cutaneous cooling, peritoneal lavage with cold solutions, and endovascular cooling with intravenous thermodes. This last option has been investigated clinically, but the results have been disappointing possibly because the devices lacked capacity to cool the patient quickly or cooling was not implemented soon enough. The mechanism of hypothermia's protection has been assumed to be energy conservation. However, whereas deep hypothermia clearly preserves ATP, mild hypothermia has only a modest effect on ATP depletion during ischaemia. Some evidence suggests that intracellular signalling pathways might be responsible for the protection. It is unknown how cooling could trigger these pathways, but, if true, then it might be possible to duplicate cooling's protection pharmacologically.

Impact of chronic kidney disease on postinfarction inflammation, oxidative stress, and left ventricular remodeling

BACKGROUND

Patients with chronic kidney disease (CKD) have poor clinical outcomes after myocardial infarction (MI). However, the precise mechanisms are unclear. We sought to determine the prognostic significance of CKD in patients with MI in relation to left ventricular (LV) remodeling.

METHODS AND RESULTS

We examined 120 consecutive patients with a reperfused first anterior ST-elevation MI. Patients were divided into 2 groups according to the presence or absence of CKD, defined as estimated glomerular filtration rates <60 mL x min x 1.73 m2. Patients with CKD had a higher incidence of in-hospital cardiac death and readmission for heart failure during follow-up, in association with a greater LV volume and lower LV ejection fraction 2 weeks after MI compared with those without CKD. Cox proportional hazards model analysis revealed that CKD was an independent predictor of major adverse cardiac events (hazard ratio=3.13, P=.001). Plasma interleukin-6 on admission, and peak serum C-reactive protein, and malondialdehyde-modified low-density lipoprotein levels during convalescence, were higher in patients with CKD than in those without.

CONCLUSIONS

Patients with CKD had poorer clinical outcomes and accelerated infarct expansion in association with enhanced inflammation and oxidative stress, as compared with non-CKD patients, suggesting a major impact of CKD in the development of LV remodeling after MI.