Ischemic Stroke after Heart Transplantation

Patterns and Risk Factors for Rehospitalizations Within the First 90 Days Following Discharge After Heart Transplantation

BACKGROUND

Heart transplantation (HT) recipients are at risk for urgent rehospitalizations following discharge. However, data on prevalence, risk factors and clinical outcomes associated with post-HT rehospitalization are limited.

METHODS

This study aims to describe patterns of urgent rehospitalizations in HT recipients at a cardiology reference center in Brazil. Rehospitalizations and deaths occurring within the first 90 days following hospital discharge were identified. Regression models were used to identify variables associated with urgent rehospitalizations.

RESULTS

A total of 239 patients were included. Of those, 118 (49.4%) presented with a rehospitalization within 90 days following hospital discharge and 5 (2.01%) died. Most patients who were rehospitalized had one new hospital admission (86.0%). The main cause of urgent rehospitalization was infection (55.0%). In the multivariate analysis, elevated C-reactive protein at discharge and the occurrence of intracranial bleeding at index hospitalization were associated with an increased risk of readmission. Longer duration of index hospitalization and use of lower doses of azathioprine were associated with a lower risk of rehospitalization.

CONCLUSION

Around half of HT recipients were rehospitalized within the first 90 days after hospital discharge. Understanding factors associated with post-HT rehospitalization may help the implementation of strategies to avoid patient morbidity and hospital costs.

Artificial Intelligence Approaches for Predicting the Risks of Durable Mechanical Circulatory Support Therapy and Cardiac Transplantation

Background: The use of AI-driven technologies in probing big data to generate better risk prediction models has been an ongoing and expanding area of investigation. The AI-driven models may perform better as compared to linear models; however, more investigations are needed in this area to refine their predictability and applicability to the field of durable MCS and cardiac transplantation. Methods: A literature review was carried out using Google Scholar/PubMed from 2000 to 2023. Results: This review defines the knowledge gaps and describes different AI-driven approaches that may be used to further our understanding. Conclusions: The limitations of current models are due to missing data, data imbalances, and the uneven distribution of variables in the datasets from which the models are derived. There is an urgent need for predictive models that can integrate a large number of clinical variables from multicenter data to account for the variability in patient characteristics that influence patient selection, outcomes, and survival for both durable MCS and HT; this may be fulfilled by AI-driven risk prediction models.

Perfusion-Dependent Focal Neurologic Deficits in a Critically Ill Heart Transplant Recipient: A Case of Tacrolimus-Associated Reversible Cerebral Vasospasm Syndrome?

TACROLIMUS, a mainstay of immunosuppression after orthotopic heart transplantation (OHT), is associated with a broad range of side effects. Vasoconstriction caused by tacrolimus has been proposed as a mechanism underlying common side effects such as hypertension and renal injury. Neurologic side effects attributed to tacrolimus include headaches, posterior reversible encephalopathy syndrome (PRES), or reversible cerebral vasospasm syndrome (RCVS). Six case reports have been published describing RCVS in the setting of tacrolimus administration after OHT. The authors report a case of perfusion-dependent focal neurologic deficits attributed to tacrolimus-induced RCVS in an OHT recipient.

Homocysteine is associated with higher risks of ischemic stroke: A systematic review and meta-analysis

BACKGROUND

High levels of homocysteine (Hct) have been associated with great risks of ischemic stroke. However, some controversy still exists. We performed a systematic review and meta-analysis to compare the levels of Hct between patients with ischemic stroke and controls.

METHODS

We performed a systematic literature search for articles reporting Hct levels of patients with occurrence of ischemic stroke. We employed a random-effects inverse-variance weighted meta-analytical approach in order to pool standardized mean differences, with estimation of τ2 through the DerSimonian-Laird method.

RESULTS

The initial search yielded 1361 studies. After careful analysis of abstracts and full texts, the meta-analysis included data from 38 studies, which involved almost 16 000 stroke events. However, only 13 studies reported means and standard deviations for cases and controls, and therefore were used in the meta-analysis. Those studies presented data from 5002 patients with stroke and 4945 controls. Standardized mean difference was 1.67 (95% CI 1.00-2.25, P < 0.01), indicating that Hct levels were significantly larger in patients with ischemic stroke compared to controls. Between-study heterogeneity was very large (I2 = 99%), particularly because three studies showed significantly large mean differences.

CONCLUSION

This meta-analysis shows that patients with ischemic stroke have higher levels of Hct compared to controls. Whether this is a modifiable risk factor remains to be assessed through larger prospective cohorts.

A Nomogram for Predicting Patent Foramen Ovale-Related Stroke Recurrence

Background

The high prevalence of patent foramen ovale (PFO) in cryptogenic stroke suggested a stroke-causing role for PFO. As risk factors for recurrence of such stroke are not recognized, clinicians cannot sufficiently identify, treat, and follow-up high-risk patients. Therefore, this study aimed to establish a prediction model for PFO-related stroke recurrence.

Methods

This study included 392 patients with PFO-related stroke in a training set and 164 patients with PFO-related stroke in an independent validation set. In the training set, independent risk factors for recurrence identified using forward stepwise Cox regression were included in nomogram 1, and those identified using least absolute shrinkage and selection operator(LASSO)regression were included in nomogram 2. Nomogram performance and discrimination were assessed using the concordance index (C-index), area under the curve (AUC), calibration curve, and decision curve analyses (DCA). The results were also validated in the validation set.

Results

Nomogram 1 was based on homocysteine (Hcy), high-sensitivity C-reactive protein (hsCRP), and albumin (ALB), and nomogram 2 was based on age, diabetes, hypertension, right-to-left shunt, ALB, prealbumin, hsCRP, and Hcy. The C-index of nomogram 1 was 0.861, which was not significantly different from that of nomogram 2 (0.893). The 2- and 5-year AUCs of nomogram 1 were 0.863 and 0.777, respectively. In the validation set, nomogram 1 still had good discrimination (C-index, 0.862; 2-year AUC, 0.839; 5-year AUC, 0.990). The calibration curve showed good homogeneity between the prediction by nomogram 1 and the actual observation. DCA demonstrated that nomogram 1 was clinically useful. Moreover, patients were successfully divided into two distinct risk groups (low and high risk) for recurrence rate by nomogram 1.

Conclusions

Nomogram 1, based on Hcy, hsCRP, and ALB levels, provided a more clinically realistic prognostic prediction for patients with PFO-related stroke. This model could help patients with PFO-related stroke to facilitate personalized prognostic evaluations.

Anterior Circulation Acute Ischemic Stroke in the Plateau of China: Risk Factors and Clinical Characteristics

Background and Purpose

Acute ischemic stroke has a high incidence in the plateau of China. It has unique characteristics compared to the plains, and the specific relationship with altitude has not yet been appreciated. This study aimed to investigate the specificity of the plateau's anterior circulation acute ischemic stroke in China.

Methods

To retrospectively collect clinical data of patients with first-episode acute ischemic stroke in the anterior circulation in Tianjin and Xining city. The differences in clinical presentation, laboratory, and imaging examinations were compared.

Results

Patients at high altitudes showed a significant trend toward lower age (61.0 ± 10.2 vs. 64.8 ± 8.1, P = 0.010) and had a history of dyslipidemia, higher levels of inflammatory markers, erythrocytosis, and alcohol abuse. The main manifestations were higher diastolic blood pressure (85.5 ± 14.0 mmHg vs. 76.8 ± 11.6 mmHg, P < 0.001), triglycerides [2.0 (1.8) mmol/L vs. 1.3 (0.9) mmol/L, P < 0.001], CRP [4.7 (4.4) mg/L vs. 2.1 (1.9) mg/L, P < 0.001], homocysteine levels [14.5 (11.7) μmol/L vs. 11.2 (5.2) μmol/L, P < 0.001]; larger infarct volume [3.5 (4.8) cm³ vs. 9.0 (6.9) cm³, P < 0.001] and worse prognosis. Patients at high altitudes had higher atherosclerotic indexes in cIMT and plaque than those in plains.

Conclusions

The natural habituation and genetic adaptation of people to the particular geo-climatic environment of the plateau have resulted in significant differences in disease characteristics. Patients with the anterior circulation acute ischemic stroke in the plateau show more unfavorable clinical manifestations and prognosis. This study provides a preliminary interpretation of the effects of altitude and suggests developing preventive and therapeutic protocol measures that are more appropriate for the plateau of China.

Trends, risk factors, and outcomes of post-operative stroke after heart transplantation: an analysis of the UNOS database

BACKGROUND

Post-operative stroke increases morbidity and mortality after cardiac surgery. Data on characteristics and outcomes of stroke after heart transplantation (HTx) are limited.

METHODS AND RESULTS

We conducted a retrospective analysis of the United Network for Organ Sharing (UNOS) database from 2009 to 2020 to identify adults who developed stroke after orthotropic HTx. Heart transplant recipients were divided according to the presence or absence of post-operative stroke. The primary endpoint was all-cause mortality. A total of 25 015 HT recipients were analysed, including 719 (2.9%) patients who suffered a post-operative stroke. The stroke rates increased from 2.1% in 2009 to 3.7% in 2019, and the risk of stroke was higher after the implantation of the new allocation system [odds ratio 1.29, 95% confidence intervals (CI) 1.06-1.56, P = 0.01]. HTx recipients with post-operative stroke were older (P = 0.008), with higher rates of prior cerebrovascular accident (CVA) (P = 0.004), prior cardiac surgery (P < 0.001), longer waitlist time (P = 0.04), higher rates of extracorporeal membrane oxygenation (ECMO) support (P < 0.001), left ventricular assist devices (LVADs) (P < 0.001), mechanical ventilation (P = 0.003), and longer ischaemic time (P < 0.001). After multivariable adjustment for recipient and donor characteristics, age, prior cardiac surgery, CVA, support with LVAD, ECMO, ischaemic time, and mechanical ventilation at the time of HTx were independent predictors of post-operative stroke. Stroke was associated with increased risk of 30 day and all-cause mortality (hazard ratio 1.49, 95% CI 1.12-1.99, P = 0.007).

CONCLUSIONS

Post-operative stroke after HTx is infrequent but associated with higher mortality. Redo sternotomy, LVAD, and ECMO support at HTx are among the risk factors identified.

Incidence, Risk Factors, and Outcomes of Stroke Following Cardiac Transplantation

Background and Purpose

Less is known about the risk factors and outcomes associated with stroke in the current era of increasing heart transplantation (HT) being performed in older patients. The impact of immunosuppression on risk of stroke has not yet been previously studied. We aimed to determine the incidence, risk factors and outcomes of stroke after HT.

Methods

We retrospectively analyzed the incidence of ischemic and hemorrhagic strokes and associated outcomes in all consecutive HT recipients transplanted between 1994 and 2016 at a single institution.

Results

Of 529 patients who underwent HT, 57 (10.7%) developed stroke, 8.1% had an ischemic events and (2.6%) had a hemorrhagic stroke. Age at HT (adjusted hazard ratio [HR] 1.33; P=0.03) and diabetes (HR, 2.60; P=0.02) were associated with increased risk of ischemic events. Patients with stroke (any type) were more likely to have worse kidney function (HR, 1.81; P=0.02) whereas patients with ischemic events were more likely to undergo combined organ transplantation (HR, 2.01; P=0.05). Cytomegalovirus infection was found to be associated with increased risk of any stroke (HR, 2.09; P=0.02).Conversion from calcineurin inhibitor to sirolimus-based immunosuppression was not found to be associated with a significant change in stroke risk (HR, 1.39; P=0. 45) compared with calcineurin inhibitor maintenance therapy. Stroke of any type and ischemic events were independently associated with increased risk of death (HR, 1.90; P=0.001 and HR, 2.14; P<0.001, respectively).

Conclusions

Stroke after HT is associated with increased mortality. Older age at HT, diabetes, renal dysfunction, and CMV infection were associated with greater risk of stroke.

Posterior Reversible Encephalopathy Syndrome Associated with Tacrolimus in Cardiac Transplantation

Background

Neurological complications occur between 50 and 70% of patients with heart transplantation, including cerebrovascular events, infections, seizures, encephalopathy, and neurotoxicity due to pharmacological immunosuppression. Mortality associated with cerebrovascular complications is 7.5% in the first 30 days and up to 5.3% after the first month and up to the first year after transplantation. Case Reports. Three heart-transplanted patients (2 men and 1 woman) treated with tacrolimus were identified. They presented with posterior reversible encephalopathy syndrome on days 5, 6, and 58 posttransplantation, respectively. In these reported cases, no sequelae were observed at 6 months follow-up.

Conclusions

Posterior reversible encephalopathy syndrome as a neurological complication in patients with HT occurred early after the procedure. Early diagnosis and treatment might reduce the risk of serious complications and mortality.

Neurologic complications of heart surgery

Cardiac surgeries are commonly associated with neurologic complications. The type and complexity of the surgery, as well as patients' comorbidities, determine the risk for these complications. Awareness and swift recognition of these complications may have significant implications on management and prognosis. Recent trials resulted in an expansion of the time window to treat patients with acute ischemic stroke with intravenous thrombolysis and/or mechanical thrombectomy using advanced neuroimaging for screening. The expanded time window increases the reperfusion treatment options for patients that suffer a periprocedural ischemic stroke. Moreover, there is now limited data available to help guide management of intracerebral hemorrhage in patients undergoing treatment with anticoagulation for highly thrombogenic conditions, such as left ventricular assist devices and mechanical valves. In addition to cerebrovascular complications patients undergoing heart surgery are at increased risk for seizures, contrast toxicity, cognitive changes, psychological complications, and peripheral nerve injuries. We review the neurological complications associated with the most common cardiac surgeries and discuss clinical presentation, diagnosis and management strategies.

Cerebrovascular risk factors associated with ischemic stroke in a young non-diabetic and non-hypertensive population: a retrospective case-control study

Background

Globally, rates of ischemic stroke (IS) have been rising among young adults. This study was designed to identify risk factors associated with IS incidence in young adults unaffected by hypertension or diabetes.

Methods

This was a retrospective case-control study of early-onset IS patients without diabetes and hypertension. Control patients were matched with healthy individuals based upon sex, age (±2 years), and BMI (±3 kg/m²) at a 1:3 ratio. Sociodemographic, clinical, and risk factor-related data pertaining to these patients was collected. The association between these risk factors and IS incidence was then assessed using conditional logistic regression models.

Results

We recruited 60 IS patients and 180 controls with mean ages of 44.37 ± 4.68 and 44.31 ± 4.71 years, respectively, for this study. Relative to controls, IS patients had significantly higher total cholesterol (TG), homocysteine (HCY), white blood cell (WBC), absolute neutrophil count (ANC), systolic blood pressure (SBP), and diastolic blood pressure (DBP) levels, and significantly lower high-density lipoprotein cholesterol (HDL-C) and triglyceride cholesterol (TC), free triiodothyronine (FT3), and free thyroxine (FT4) levels (all P < 0.05). After controlling for potential confounding factors, HCY and ANC were found to be significantly positively associated with IS incidence (OR 1.518, 95%CI 1.165–1.977, P = 0.002 and OR 2.418, 95%CI 1.061–5.511, P = 0.036, respectively), whereas HDL-C and FT3 levels were negatively correlated with IS incidence (OR 0.001, 95%CI 0.000–0.083, P = 0.003 and OR 0.053, 95%CI 0.008–0.326, P = 0.002, respectively).

Conclusions

In young non-diabetic and non-hypertensive patients, lower HDL-C and FT3 levels and higher HCY and ANC levels may be associated with an elevated risk of IS. Additional prospective studies of large patient cohorts will be essential to validate these findings.

[Arterial hypertension after heart transplantation]

Aim To evaluate incidence of arterial hypertension (AH) in the posttransplantation period and to identify risk factors for this complication.Materials and methods From January, 2010 through December, 2017, 96 heart transplantations (HT) (70 men and 26 women aged 46.5±13.9 years) were performed. During the first month following HT, 8 recipients died and were excluded from the analysis. The retrospective evaluation of results included 88 patients followed up for more than one year.Results For the entire post-HT period (maximum 92 months), AH was observed in 75 of 88 (85%) recipients. Post-HT AH was correlated with male gender (r=0.24; p=0.031), history of smoking before HT (r=0.45; p&lt;0.001), history of ischemic heart disease (IHD) (r=0.28; p=0.01), older age (r=0.35; p=0.001), higher body weight index (r=0.37; p=0.0005), creatinine level (r=0.37; p=0.001), and low-density lipoprotein cholesterol level (r=0.27; p=0.04). Interrelations with other AH risk factors were not found. Most patients developed AH within the first two years after HT. During the first year, AH was diagnosed in 60% (53 of 88) of patients (relapse, 85% (n=29); newly diagnosed, 45% (n=24), p=0.0003). At two years, AH was detected in 79% (46 of 58) of patients (relapse, 53% (n=18); newly diagnosed, 53% (n=28), p=0.9). All recipients received an adequate antihypertensive therapy. 40-63% of patients required a single-drug therapy at different points of follow-up; from 29 to 45% of patients required a two-drug therapy, and 5-15% of patients required three or more drugs. During all 5 years of treatment, most patients used angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) (70-87%) and slow calcium channel blockers (SCCB) (48-53%). The presence of AH following HT was associated with development of all cardiovascular events (CVE; r=0.31; p=0.012) whereas persistent AH, which required a combination antihypertensive treatment, was associated with a high mortality (r=0.61; p=0.015).Conclusion AH is a frequent complication of HT (85%), which is newly diagnosed in most patients during the first two years. AH incidence was higher for male recipients with a history of IHD, hypertension, and smoking. Approximately half of patients required only a single-drug antihypertensive therapy. After HT, the most frequently prescribed drugs included ACE inhibitors or ARBs and SCCBs (70-87% and 48-53%, respectively, depending on the time elapsed after HT). Persistent AH requiring a treatment with two or more antihypertensive drugs was associated with development of all CVEs and a higher long-term mortality.

Comparison of serum Lp-PLA2 levels in ischemic stroke patients with H-type hypertension or non-H-type hypertension

Background

Increased serum Lp‐PLA2 levels have been reported in patients who experienced an ischemic stroke; however, the relationship between Lp‐PLA2 and H‐type hypertension in patients with ischemic stroke remains unclear.

Methods

In the present study, we investigated the correlation between serum Lp‐PLA2 and H‐type hypertension in patients with ischemic stroke. A total of 135 patients who experienced acute ischemic stroke were enrolled in Tianjin Huanhu Hospital during October 2015 to May 2016. The demographic characteristics of the patients were collected, and biochemical parameters were detected.

Results

Among the 135 patients, 111 patients had essential hypertension, including 41 patients with H‐type hypertension and 70 with non‐H‐type hypertension. There were higher proportions of males and patients with diabetes mellitus in the H‐type hypertension group compared with the non‐H‐type hypertension group (P < .05). Lp‐PLA2, glucose, and LDL‐C levels were higher in the H‐type hypertension group than in the non‐H‐type hypertension group (P < .05). Multivariate logistic regression showed that Lp‐PLA2 levels >208.46 mg/L were independently associated with H‐type hypertension in patients with ischemic stroke (OR: 2.560, 95% CI: 1.085‐6.040, P = .032). The area under the ROC curve of Lp‐PAL2 levels in the H‐type hypertension group was 0.665 (95% CI: 0.561‐0.768, P = .004).

Conclusion

Synergetic effects of H‐type hypertension and Lp‐PLA2 levels were noted in the pathogenesis of ischemic stroke.

Telomere length, vitamin B12 and mortality in persons undergoing coronary angiography: the Ludwigshafen risk and cardiovascular health study

Background: Vitamin B12 (B12) deficiency and excess are associated with increased risk of age-related-diseases and mortality. It has been suggested that high- and low-B12 concentrations link to increased mortality through accelerated genomic aging and inflammation. Evidence to support this is limited.

Results: B12 was associated with all-cause-mortality, RTL and hsCRP in a non-linear fashion. The association between B12 and mortality was not independent, as it lost significance after adjustment for potential confounders. In the lowest-(LB12) and highest-(HB12) quartiles of B12 mortality was higher than in the mid-range (HR:LB12:1.23;CI95%:1.06-1.43; HR:HB12:1.24;CI95%:1.06-1.44). We divided subjects with LB12 in quartiles of their RTL. Those with the longest-telomeres had a lower mortality-rate (HR:0.57;95%CI:0.39-0.83) and lower homocysteine than those with the shortest-telomeres. Amongst subjects with HB12, those with long-telomeres also had a lower mortality than those with short-telomeres (HR:0.40;95%CI:0.27-0.59). IL-6 and hsCRP concentrations were low in HB12LT but were high in HB12ST.

Methods: B12, homocysteine, telomere length (RTL), interleukin-6 (IL-6) and high-sensitive-C-reactive-protein (hsCRP) were measured in 2970 participants of the LURIC study.

Conclusions: Mortality, stratified according to B12 and RTL, seems to be driven by different mechanisms. In LB12 and HB12 subjects, mortality and accelerated telomere shortening might be driven by homocysteine and inflammation, respectively.

Percutaneous coronary intervention in patients hospitalized for non-ST-elevation myocardial infarction and the risk of postdischarge ischemic stroke at 6-month, 1-year, and 3-year follow-ups

Percutaneous coronary intervention (PCI) is suggested for treating patients with non-ST-elevation myocardial infarction (NSTEMI) to reduce adverse cardiovascular events. However, the short- and long-term effects of PCI on the risk of postdischarge ischemic stroke (IS) in patients hospitalized for NSTEMI remain unclear. This study investigated the association of PCI on the risk of postdischarge IS in patients hospitalized for NSTEMI at different period follow-ups. A population-based cohort study was conducted using data from Taiwan's National Health Insurance Research Database. Propensity score matching (PSM) was used to select 6079 pairs of the patients with NSTEMI treated invasively by PCI (received PCI during hospitalization) and initial conservative strategy (did not receive PCI during hospitalization) with similar baseline characteristics for evaluation. After adjustment for patients' clinical variables and the duration of dual antiplatelet therapy, PCI was associated with a decreased risk of postdischarge IS at 6-month, 1-year, and 3-year follow-ups [adjusted hazard ratio (aHR) = 0.41, 95% confidence interval (CI) = 0.26-0.67, p < 0.001; aHR = 0.61, 95% CI 0.43-0.86, p = 0.004; and aHR = 0.69, 95% CI 0.54-0.89, p = 0.005respectively]. In the patients who had a CHA₂DS₂-VASc score of ≥2, PCI was also associated with a decreased risk of postdischarge IS at 6-month, 1-year, and 3-year follow-ups (aHR = 0.54, 95% CI 0.36-0.83, p = 0.005; aHR = 0.72, 95% CI 0.52-1.00, p = 0.048; and aHR =0.73, 95% CI 0.58-0.91, p = 0.005, respectively). These findings suggested that PCI might reduce the risk of postdischarge IS in patients hospitalized for NSTEMI.

Factor VIIa administration in orthotopic heart transplant recipients and its impact on thromboembolic events and post-transplant outcomes

Recombinant, activated factor VIIa (rFVIIa) is used during cardiac surgeries to mitigate refractory coagulopathic bleeding. The purpose of this study was to examine whether rFVIIa use in orthotopic heart transplant (OHT) recipients was associated with a higher incidence of thromboembolic (TE) events compared to patients who did not. A single-center, retrospective, cohort study was performed on OHT recipients who received rFVIIa for refractory coagulopathic bleeding from January 2013 to December 2015. Patients were evaluated for up to 6 months after transplantation and assessed for TE events, rejection, readmissions, graft survival, and patient survival. Categorical variables were analyzed using the Chi square test while student's t or ANOVA testing was utilized for continuous variables. Of the 62 patients who met inclusion criteria, 27 patients received rFVIIa, and 35 patients were selected for the control group. The overall incidence of TE events was not significantly different between patients who received rFVIIa compared to patients in the control group (14.8% vs 11.4%) (p = 0.69). Within 14 days, 14.81% of rFVIIa patients suffered a TE event compared to 5.7% of the control group (p = 0.23). Rejection, readmissions, graft survival, and patient survival were not significantly different at any time points. Use of rFVIIa in heart transplantation showed no difference in the overall rate of TE events, however, there was a nonsignificant trend toward higher risk of early TE development in the rFVIIa group compared to the control group.

Autonomic Nervous System and Stress to Predict Secondary Ischemic Events after Transient Ischemic Attack or Minor Stroke: Possible Implications of Heart Rate Variability

Transient ischemic attack (TIA) and minor stroke have high risks of recurrence and deterioration into severe ischemic strokes. Risk stratification of TIA and minor stroke is essential for early effective treatment. Traditional tools have only moderate predictive value, likely due to their inclusion of the limited number of stroke risk factors. Our review follows Hans Selye’s fundamental work on stress theory and the progressive shift of the autonomic nervous system (ANS) from adaptation to disease when stress becomes chronic. We will first show that traditional risk factors and acute triggers of ischemic stroke are chronic and acute stress factors or “stressors,” respectively. Our first review shows solid evidence of the relationship between chronic stress and stroke occurrence. The stress response is tightly regulated by the ANS whose function can be assessed with heart rate variability (HRV). Our second review demonstrates that stress-related risk factors of ischemic stroke are correlated with ANS dysfunction and impaired HRV. Our conclusions support the idea that HRV parameters may represent the combined effects of all body stressors that are risk factors for ischemic stroke and, thus, may be of important predictive value for the risk of subsequent ischemic events after TIA or minor stroke.

Perioperative stroke: pathophysiology and management

Although perioperative stroke is uncommon during low-risk non-vascular surgery, if it occurs, it can negatively impact recovery from the surgery and functional outcome. Based on the Society for Neuroscience in Anesthesiology and Critical Care Consensus Statement, perioperative stroke includes intraoperative stroke, as well as postoperative stroke developing within 30 days after surgery. Factors related to perioperative stroke include age, sex, a history of stroke or transient ischemic attack, cardiac surgery (aortic surgery, mitral valve surgery, or coronary artery bypass graft surgery), and neurosurgery (external carotid-internal carotid bypass surgery, carotid endarterectomy, or aneurysm clipping). Concomitant carotid and cardiac surgery may further increase the risk of perioperative stroke. Preventive strategies should be individualized based on patient factors, including cerebrovascular reserve capacity and the time interval since the previous stroke.

Cardiovascular disease risk in patients receiving organ transplantation: a national cohort study

Although organ transplantation is the definitive treatment for end-stage organ failure, the post-transplant outcomes can be substantially influenced by cardiovascular complications. A national cohort study was performed to estimate risks of cardiovascular diseases in those with heart, lung, kidney, and liver transplantation. This cohort study consisted of 5978 solid organ transplantations identified using the Taiwan National Health Insurance Database. Cardiovascular and mortality risks in transplant recipients were evaluated using standardized incidence ratios, excess absolute risks, and standardized mortality ratios as compared to those in the general population. In heart, kidney, and liver recipients, the standardized incidence ratios of overall cardiovascular diseases were 9.41 (7.75-11.44), 3.32 (2.29-3.77), and 1.4 (1.15-1.7) and the overall standardized mortality ratios were 5.23 (4.54-6.03), 1.48 (1.34-1.63), and 3.95 (3.64-4.28), respectively. Except for heart organ recipients who were at highest risk for coronary artery disease with a standardized incidence ratio of 13.12 (10.57-16.29), kidney and liver organ recipients had a ninefold increased risk in developing deep vein thrombosis post-transplant. In conclusion, solid organ transplant patients are at risk of cardiovascular disease, in particular, deep vein thrombosis, which may warrant early identification of high-risk patients in addition to prompt and adequate thromboprophylaxis perioperatively.

Role of Homocysteine in the Ischemic Stroke and Development of Ischemic Tolerance

Homocysteine (Hcy) is a toxic, sulfur-containing intermediate of methionine metabolism. Hyperhomocysteinemia (hHcy), as a consequence of impaired Hcy metabolism or defects in crucial co-factors that participate in its recycling, is assumed as an independent human stroke risk factor. Neural cells are sensitive to prolonged hHcy treatment, because Hcy cannot be metabolized either by the transsulfuration pathway or by the folate/vitamin B12 independent remethylation pathway. Its detrimental effect after ischemia-induced damage includes accumulation of reactive oxygen species (ROS) and posttranslational modifications of proteins via homocysteinylation and thiolation. Ischemic preconditioning (IPC) is an adaptive response of the CNS to sub-lethal ischemia, which elevates tissues tolerance to subsequent ischemia. The main focus of this review is on the recent data on homocysteine metabolism and mechanisms of its neurotoxicity. In this context, the review documents an increased oxidative stress and functional modification of enzymes involved in redox balance in experimentally induced hyperhomocysteinemia. It also gives an interpretation whether hyperhomocysteinemia alone or in combination with IPC affects the ischemia-induced neurodegenerative changes as well as intracellular signaling. Studies document that hHcy alone significantly increased Fluoro-Jade C- and TUNEL-positive cell neurodegeneration in the rat hippocampus as well as in the cortex. IPC, even if combined with hHcy, could still preserve the neuronal tissue from the lethal ischemic effects. This review also describes the changes in the mitogen-activated protein kinase (MAPK) protein pathways following ischemic injury and IPC. These studies provide evidence for the interplay and tight integration between ERK and p38 MAPK signaling mechanisms in response to the hHcy and also in association of hHcy with ischemia/IPC challenge in the rat brain. Further investigations of the protective factors leading to ischemic tolerance and recognition of the co-morbid risk factors would result in development of new avenues for exploration of novel therapeutics against ischemia and stroke.

Neurologic Complications After Cardiac Transplant

OBJECTIVES

Cardiac transplant is the best available therapy for patients with end-stage heart failure. Neurologic complications occur at a rate of 30% to 70% in patients undergoing cardiac transplant, and they affect mortality and morbidity of these patients. Risk factors for neurologic complications include immunosuppressive medication toxicity, infections, brain lesions, and metabolic disorders. The aim of our study was to determine the incidence of neurologic complications in adult patients undergoing cardiac transplant.

MATERIALS AND METHODS

We retrospectively evaluated the medical records of 70 patients who underwent cardiac transplant between 2004 and April 2016. We recorded the demographic data, neurologic symptoms, neurologic examination findings, laboratory test results, brain imaging study results, and treatments received of the patients.

RESULTS

Of the 70 patients enrolled, 55 were male and 15 were female patients. The age range was 18 to 63 years, and the mean age was 42.4 years. Twelve patients had encephalopathy, 4 had neuropathic pain, 3 had tremor, 2 had ischemic cerebrovascular accident, 7 had posterior reversible encephalopathy syndrome, and 1 had drop foot. Encephalopathy usually developed secondary to other neurologic disorders. The incidence of neurologic complications in adult patients undergoing cardiac transplant was 30%.

CONCLUSIONS

Neurologic complications are common after cardiac transplant. We observed an incidence of 30% for neurologic complications in our clinic, with encephalopathy being the most common complication. Encephalopathy most commonly developed secondary to posterior reversible encephalopathy syndrome.