Cardiac dysfunction in the CABG patient

Enhancing mortality prediction after coronary artery bypass graft: a machine learning approach utilizing EuroScore

Aim: We developed a machine learning model using EuroScore assumptions and preoperative and intraoperative risk factors to predict mortality after coronary artery bypass graft (CABG). Materials & methods: We retrospectively examined data from 108 CABG patients at King Abdullah University Hospital, classifying them into risk groups via EuroScore and predicting mortality through random forest classification. Results: High-risk patients displayed longer surgical times and significant factors such as age and surgery choice. The median EuroScore was 0.95 (0.5-6.4). The model yielded high AUC scores (0.98, 0.95) indicating strong predictive accuracy. Conclusion: Our findings showed that the machine learning models combined with the EuroScore significantly improve post-CABG mortality prediction. For further validation, larger datasets are needed.

Impact of high intensity interval and moderate continuous training on plasma ratios of ProBNP1-108/BNP1-32 and NT-pro-BNP1-76/BNP1-32 after coronary artery bypass grafting surgery

Background: ProBNP1-108/BNP1-32, and NT-pro-BNP1-76/BNP1-32 ratios are significant indices for predicting complications after coronary artery bypass grafting (CABG) surgery. However, the effect of aerobic training types on these biomarkers has not been fully understood. So, the current study aimed to determine the impact of aerobic interval and continuous training programs on plasma ratios of ProBNP1-108/BNP1-32 and NT-pro-BNP1-76/BNP1-32 after coronary artery bypass grafting surgery. Method: 36 patients were selected purposive (27 men and 9 women with mean of age 60.32 ± 5.81 years, height 164.64 ± 9.25 cm, weight 73.86 ± 14.23 kg, fat 32.30 ± 4.28, SBP 142.67 ± 6.49, DBP 84.5 ± 5.16 mmHg in seated position at rest situation and functional capacity of 7.08 ± 2.49 METs) and then divided randomly into three groups: control (C) group (without training program) moderate continuous training (MCT) and high intensity interval training (HIIT) (exercise training program was performed 3 days/week for 8 weeks) with intensities 65%-80% and 80%-95% of reserve heart rate in order. Blood samples were taken 48 h before the first session and 48 h after the last training session to measure the plasma levels of ProBNP1-108, corin enzyme, BNP1-32, and NT-pro-BNP1-76 using the enzyme-linked immunosorbent assay (ELISA) technique. Wilcoxin and kruskal wallis tests were used for analyzing data. Results: The plasma corin enzyme was increased, and the ratios of proBNP1-108/BNP1-32 and NT-pro-BNP1-76/BNP1-32 were reduced in both training groups in compared with control group (p = 0.004, p = 0000, p = 0.016, p = 0.003, p = 0.009, and p = 0.016) when there was no significant difference was found between training groups (p = 0.074, p = 450, and p = 0.295). Conclusion: Both high intensity interval training and moderate continuous training in compared with inactivity have positive effects on ratios of ProBNP1-108/BNP1-32, NT-pro-BNP1-76/BNP1-32 and could be effective to promote the health of coronary arteries and prevention of HF in post-CABG patients.

Prognostic Value of Thyroid Hormone FT3 in General Patients Admitted to the Intensive Care Unit

Low plasma triiodothyronine (T3) concentration indicates nonthyroidal illness syndrome (NTIS), which might be associated with a poor outcome in patients in the intensive care unit (ICU). This study evaluated the relationship between NTIS and prognostic indicators in patients admitted to the ICU and examined the fT3 cut-off points that could be associated with 28-day mortality. This prospective observational study included patients admitted to the ICU of The Third Hospital of Hebei Medical University from February to November 2018. The baseline variables and the occurrence of low free T3 (FT3) were collected. The patients were divided into the NTIS (FT3 < 3.28) and non-NTIS groups. Among 305 patients, 118 (38.7%) were in the NTIS group. FT3 (P < 0.001) and FT4 (P = 0.001) were lower, while the 28-day mortality rate (P < 0.001) and hospitalization expenses in ICU (P = 0.001) were higher in the NTIS group. The univariable analyses identified NTIS, FT3, free thyroxine/FT3, APACHEII, sequential organ failure score, duration of mechanical ventilation, creatinine, oxygenation index, white blood cells, albumin, age, and brain natriuretic peptide as being associated with 28-day mortality (all P < 0.05). The cut-off value of FT3 for 28-day mortality was 2.88 pmol/L. The 28-day mortality rate and hospitalization expenses in the ICU were higher in patients with NTIS. NTIS was independently associated with 28-day mortality.

Use of Smart Technology for the Early Diagnosis of Complications After Cardiac Surgery: The Box 2.0 Study Protocol

BACKGROUND

Atrial fibrillation (AF), sternal wound infection, and cardiac decompensation are complications that can occur after cardiac surgery. Early detection of these complications is clinically relevant, as early treatment is associated with better clinical outcomes. Remote monitoring with the use of a smartphone (mobile health [mHealth]) might improve the early detection of complications after cardiac surgery.

OBJECTIVE

The primary aim of this study is to compare the detection rate of AF diagnosed with an mHealth solution to the detection rate of AF diagnosed with standard care. Secondary objectives include detection of sternal wound infection and cardiac decompensation, as well as assessment of quality of life, patient satisfaction, and cost-effectiveness.

METHODS

The Box 2.0 is a study with a prospective intervention group and a historical control group for comparison. Patients undergoing cardiac surgery at Leiden University Medical Center are eligible for enrollment. In this study, 365 historical patients will be used as controls and 365 other participants will be asked to receive either The Box 2.0 intervention consisting of seven home measurement devices along with a video consultation 2 weeks after discharge or standard cardiac care for 3 months. Patient information will be analyzed according to the intention-to-treat principle. The Box 2.0 devices include a blood pressure monitor, thermometer, weight scale, step count watch, single-lead electrocardiogram (ECG) device, 12-lead ECG device, and pulse oximeter.

RESULTS

The study started in November 2018. The primary outcome of this study is the detection rate of AF in both groups. Quality of life is measured with the five-level EuroQol five-dimension (EQ-5D-5L) questionnaire. Cost-effectiveness is calculated from a society perspective using prices from Dutch costing guidelines and quality of life data from the study. In the historical cohort, 93.9% (336/358) completed the EQ-5D-5L and patient satisfaction questionnaires 3 months after cardiac surgery.

CONCLUSIONS

The rationale and design of a study to investigate mHealth devices in postoperative cardiac surgery patients are presented. The first results are expected in September 2020.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03690492; http://clinicaltrials.gov/show/NCT03690492.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/16326.

Mitochondrial Bioenergetics During Ischemia and Reperfusion

During ischemia and reperfusion (I/R) mitochondria suffer a deficiency to supply the cardiomyocyte with chemical energy, but also contribute to the cytosolic ionic alterations especially of Ca²⁺. Their free calcium concentration ([Ca²⁺]m) mainly depends on mitochondrial entrance through the uniporter (UCam) and extrusion in exchange with Na⁺ (mNCX) driven by the electrochemical gradient (ΔΨm). Cardiac energetic is frequently estimated by the oxygen consumption, which determines metabolism coupled to ATP production and to the maintaining of ΔΨm. Nevertheless, a better estimation of heart energy consumption is the total heat release associated to ATP hydrolysis, metabolism, and binding reactions, which is measurable either in the presence or the absence of oxygenation or perfusion. Consequently, a mechano-calorimetrical approach on isolated hearts gives a tool to evaluate muscle economy. The mitochondrial role during I/R depends on the injury degree. We investigated the role of the mitochondrial Ca²⁺ transporters in the energetic of hearts stunned by a model of no-flow I/R in rat hearts. This chapter explores an integrated view of previous and new results which give evidences to the mitochondrial role in cardiac stunning by ischemia o hypoxia, and the influence of thyroid alterations and cardioprotective strategies, such as cardioplegic solutions (high K-low Ca, pyruvate) and the phytoestrogen genistein in both sex. Rat ventricles were perfused in a flow-calorimeter at either 30 °C or 37 °C to continuously measure the left ventricular pressure (LVP) and total heat rate (Ht). A pharmacological treatment was done before exposing to no-flow I and R. The post-ischemic contractile (PICR as %) and energetical (Ht) recovery and muscle economy (Eco: P/Ht) were determined during stunning. The functional interaction between mitochondria (Mit) and sarcoplasmic reticulum (SR) was evaluated with selective mitochondrial inhibitors in hearts reperfused with Krebs-10 mM caffeine-36 mM Na⁺. The caffeine induced contracture (CIC) was due to SR Ca²⁺ release, while relaxation mainly depends on mitochondrial Ca²⁺ uptake since neither SL-NCX nor SERCA are functional under this media. The ratio of area-under-curves over ischemic values (AUC-ΔHt/AUC-ΔLVP) estimates the energetical consumption (EC) to maintain CIC. Relaxation of CIC was accelerated by inhibition of mNCX or by adding the aerobic substrate pyruvate, while both increased EC. Contrarily, relaxation was slowed by cardioplegia (high K-low Ca Krebs) and by inhibition of UCam. Thus, Mit regulate the cytosolic [Ca²⁺] and SR Ca²⁺ content. Both, hyperthyroidism (HpT) and hypothyroidism (HypoT) reduced the peak of CIC but increased EC, in spite of improving PICR. Both, CIC and PICR in HpT were also sensitive to inhibition of mNCX or UCam, suggesting that Mit contribute to regulate the SR store and Ca²⁺ release. The interaction between mitochondria and SR and the energetic consequences were also analyzed for the effects of genistein in hearts exposed to I/R, and for the hypoxia/reoxygenation process. Our results give evidence about the mitochondrial regulation of both PICR and energetic consumption during stunning, through the Ca²⁺ movement.

Ultrastructural and histomorphologic properties of the internal thoracic artery: implications for coronary revascularization

Coronary artery disease represents a major health problem worldwide for which coronary artery bypass surgery remains a standard of care. Among the several grafts that are available, the internal thoracic artery (ITA) has long been considered the best as several advantages have been described compared with other vessels (e.g. saphenous vein or radial artery), namely, an absent to minor atherosclerotic development. In fact, several studies showed the presence of preatherosclerotic lesions, such as intimal and/or medial thickening, medial fibrosis, among others, in the presence of certain cardiovascular risk factors as well as established atherosclerotic lesions (i.e. type II or more lesions). This paper primarily aimed at reviewing the current knowledge on the histomorphological characteristics of ITA as well as the comparative histomorphology of ITA with other vessel grafts currently in use in coronary surgery. As some of the evidence is not clear or consensual, this paper also aimed at reviewing the main histopathological, histomorphometrical, and ultrastructural findings in ITAs from patients with known cardiovascular risk factors (e.g. aging, obesity, hypertension, diabetes, smoking, and others). As the presence of preatherosclerotic and/or atherosclerotic lesions may compromise the success of the myocardial revascularization and lead to graft failure, contributing toward the associated morbidity and/or mortality, it is essential to improve the scientific knowledge on the structural characterization of ITAs and its correlation with the cardiovascular risk profile.

Fluid management in the cardiothoracic intensive care unit: diuresis--diuretics and hemofiltration

PURPOSE OF REVIEW

The present review discusses the current concepts of fluid management in cardiothoracic surgery, and its clinical implications with special reference to organ-related complications and their prevention.

RECENT FINDINGS

Current strategies in fluid management for cardiothoracic patients, various fluid formulation, and the preventive strategies for minimizing fluid-related complications are described, with particular reference to new discoveries and controversies that have arisen from recent literature.

SUMMARY

The optimal fluid management in cardiothoracic patients has not been settled. Results of recent clinical published trials highlight the need for minimizing fluid administration and attempting to use diuretics to achieve a negative fluid, although hypovolemia and hypoperfusion should be carefully considered. An individualized optimization of fluid status, using goal-directed therapy, has emerged as a possible preferable approach. The old debate between crystalloid and colloid solutions has been partially solved, as some colloids have demonstrated deleterious effect on renal function and coagulation system. Various preventive strategies have also emerged for minimizing fluid-related complications.

Endothelium-dependent vasoactivity of the human internal mammary artery

Coronary artery disease is recognized as a major health problem worldwide, particularly because of the associated morbidity and mortality. Coronary artery bypass grafting has been an established mainstay in the treatment of this disease for almost half a century and is arguably the most intensively studied surgical procedure ever undertaken. Because of its unique properties, the human internal mammary artery has long been considered the best graft to use in this type of surgery. Previous studies have shown several advantages of this graft compared with others, that is, lower incidence of atherosclerosis. However, few comparative studies on the reactivity of this artery have been published. Moreover, these studies usually focus on isolated cardiovascular risk factors rather than combined risk factors. In fact, patients who require coronary revascularization usually present multiple risk factors, which can interfere with several pathways of regulation of vascular function, namely endothelial function. Several diseases and cardiovascular risk factors have been shown to interfere with endothelial function, promoting the production of vasoconstrictors, inhibiting the production of vasodilators, or both, and thus eventually leading to endothelial dysfunction. Therefore, it is of great interest to study the endothelial function, particularly of the human internal mammary artery, in the presence of combined cardiovascular risk factors and concomitant diseases. Many techniques have been developed to assess the endothelial function, in particular, studies on isolated arteries, as well as spectroscopic, electrochemical, and immunological methods, among others.

Thyroid hormone and the stunned myocardium

Acute critically ill patients experience a rapid decline in plasma free thyroid hormone levels (free triiodothyronine (FT3) and free levothyroxine (FT4)), with a marked elevation of reverse T3, recognized as the euthyroid sick syndrome (ESS) or low-T3 syndrome. The ESS is also often associated with depressed myocardial function, sometimes referred to as the 'stunned myocardium'. Its clinical effects may vary from minimal hemodynamic impairment to cardiogenic shock. Medical management may range from aspirin alone to placement of a left ventricular assist device. With adequate supportive therapy, recovery usually occurs within days or weeks. The effect of T3/T4 therapy has been studied in three conditions in which the ESS and myocardial functional depression have been documented - i) transient regional myocardial ischemia and reperfusion, ii) transient global myocardial ischemia in patients undergoing cardiac surgery on cardiopulmonary bypass, and iii) transient inadequate global myocardial perfusion in brain-dead potential organ donors. Under all three conditions, myocardial ischemia leads to rapid loss of high-energy phosphates, accumulation of myocardial tissue lactate, and probably loss of homeostasis of cytosolic calcium, which may further increase cell injury. There is an inability to generate ATP through the Krebs cycle, which reduces the high-energy phosphate pool essential for all cell ATPases. Under all three conditions, following administration of T3/T4, the myocardial dysfunction was rapidly reversed. We, therefore, cautiously advocate the use of thyroid hormonal therapy to any patient with the ESS and/or a stunned myocardium.

Myocardial viability and microvascular obstruction: role of cardiac magnetic resonance imaging

Established coronary artery disease has a prevalence of 7% in adult Americans, accounting for 16 million people. As morbidity and mortality rates have risen, research efforts to identify the pathophysiologic mechanisms of systolic dysfunction have risen in parallel. The current goal is to develop new therapeutic strategies with the potential to reverse systolic dysfunction in patients with established coronary artery disease. Cardiac magnetic resonance imaging has gained a key role in cardio vascular medicine. We will comment on the potential pivotal role of cardiac magnetic resonance imaging for the assessment of myocardial viability, including hibernating and stunned myocardium and microvascular obstruction.