Cerebrovascular disease as a complication of cardiac transplantation

Heart Transplantation-Postoperative Considerations

Heart transplantation (HT) remains the best treatment of patients with severe heart failure who are deemed to be transplant candidates. The authors discuss postoperative management of the HT recipient by system, emphasizing areas where care might differ from other cardiac surgery patients. Working together, critical care physicians, heart transplant surgeons and cardiologists, advanced practice providers, pharmacists, transplant coordinators, nursing staff, physical therapists, occupational therapists, rehabilitation specialists, nutritionists, health psychologists, social workers, and the patient and their loved ones partner to increase the likelihood of a successful outcome.

Early Postoperative Neurologic Events Are Associated With Worse Outcome and Fatal Midterm Survival After Adult Heart Transplantation

Background Neurologic events during primary stay in heart transplant (HTx) recipients may be associated with reduced outcome and survival, which we aim to explore with the current study. Methods and Results We screened and included all patients undergoing HTx in our center between September 2010 and December 2022 (n=268) and checked for the occurrence of neurologic events within their index stay. Neurologic events were defined as ischemic stroke, hemorrhage, hypoxic ischemic injury, or acute symptomatic neurologic dysfunction without central nervous system injury. The cohort was then divided into recipients with (n=33) and without (n=235) neurologic events after HTx. Using a multivariable Cox regression model, the association of neurologic events after HTx and survival was assessed. Recipients with neurologic events displayed a longer intensive care unit stay (30 versus 16 days; P=0.009), longer mechanical ventilation (192 versus 48 hours; P<0.001), and higher need for blood transfusion, and need for hemodialysis after HTx was substantially higher (81% versus 55%; P=0.01). Resternotomy (36% versus 26%; P=0.05) and mechanical life support (extracorporeal life support) after HTx (46% versus 24%; P=0.02) were also significantly higher in patients with neurologic events. Covariable-adjusted multivariable Cox regression analysis revealed a significant independent association of neurologic events and increased 30-day (hazard ratio [HR], 2.5 [95% CI, 1.0-6.0]; P=0.049), 1-year (HR, 2.2 [95% CI, 1.1-4.3]; P=0.019), and overall (HR, 2.5 [95% CI, 1.5-4.2]; P<0.001) mortality after HTx and reduced Kaplan-Meier survival up to 5 years after HTx (P<0.001). Conclusions Neurologic events after HTx were strongly and independently associated with worse postoperative outcome and reduced survival up to 5 years after HTx.

Children who stroke on VAD support: when is it safe to transplant and what are their outcomes?

OBJECTIVE

Ventricular assist devices (VADs) increase waitlist survival, yet the risk of stroke remains notable. The purpose of this study was to analyze how strokes on VAD support impact post-transplant (post-Tx) outcomes in children.

METHODS

520 pediatric (<18 yo) heart transplant candidates listed from January 2011 to April 2018 with a VAD implant date were matched between the United Network of Organ Sharing and Pediatric Health Information System databases. Patients were divided into pre-Tx Stroke and No Stroke cohorts.

RESULTS

81% of the 520 patients were transplanted. 28% (n=146) had a pre-Tx Stroke. 59% (n=89) of the Stroke patients were transplanted at a median of 57 (IQR 17-102) days from stroke. Significantly more No Stroke cohort (90%) were transplanted (p<0.001). There was no difference in post-Tx survival between the Stroke and No Stroke cohorts (p=0.440). Time between stroke and transplant for patients who died within one year of transplant was 32.0 days (median) compared to 60.5 days for those alive > 1year (p=0.18). Regarding patients in whom time from stroke to transplant was more than 60 days, one-year survival of Stroke vs. No Stroke patients was 96% vs. 95% (p=0.811), respectively.

CONCLUSION

Patients with stroke during VAD support, once transplanted, enjoy similar survival compared to No Stroke patients. We hypothesize that allowing Stroke patients more time to recover could improve post-Tx outcomes. Unfortunately, the ideal duration of time between stroke and safe transplantation could not be determined and will require more detailed and larger studies in the future.

Neurologic Complications in Heart Transplant Recipients Readmitted to the Intensive Care Unit

Introduction Neurologic complications after transplantation surgery are major causes of morbidity, and the incidence of neurologic complications among heart transplant recipients varies from 7% to 81%. In our study, we aimed to determine the incidence, etiologies, and risk factors of neurologic complications among patients readmitted to the intensive care unit (ICU) after heart transplantation. Method In this retrospective cohort study, the medical records of all patients who underwent cardiac transplantation from February 2003 to July 2019 were reviewed, and those admitted to the ICU due to neurologic complications during the early and late postoperative period were evaluated. The patients were divided into two groups based on the development of neurologic complications to compare demographic and other characteristics. Results A total of 130 heart transplant recipients were analyzed. We excluded 33 patients from the study because they either had neurologic complications or died postoperatively without discharge from the intensive care unit. The mean age of the cohort was 35.4 ± 18.5 years, and 74 (76.3%) were male. Out of those 97 heart transplant recipients, 22 (22.7%) developed neurologic complications. Five patients (22.7% ) were admitted to the ICU in the first month, six patients (27.3%) were admitted to the ICU between one and six months, and 11 patients (50%) were admitted to the ICU six months after transplantation due to neurologic complications. The most common diagnosis was posterior reversible encephalopathy syndrome (PRES) (n = 6, 27.3%). The other diagnoses were calcineurin inhibitor toxicity (n = 5, 22.7%), intracranial hemorrhage (n = 3, 13.6%), seizures (n = 2, 9.2%), stroke (n = 2, 9.2%), femoral neuropathy (n = 1, 4.5%), myopathy (n = 1, 4.5%), phrenic nerve damage (n = 1, 4.5%), and cerebral abscess (n = 1, 4.5%). The rate of neurologic complications was higher in males when compared with females (p = 0.03). Both groups were similar in terms of the etiologies of cardiac failure, coexisting disease, and anticoagulant and immunosuppressive usage. The requirement for mechanical ventilation, renal replacement therapy, and the incidence of acute kidney injury were similar in both groups (p > 0.05). The incidence of sepsis was significantly higher in patients with neurologic complications (n = 8, 36.4%, versus n = 5, 6.7%; p < 0.001). The mean length of hospital stay was significantly higher in patients with neurologic complications (21.4 ± 15.8 versus 11.1 ± 13.3 days, p = 0.01). The risk of developing neurologic complications is 3.036 times higher in males, and this is statistically significant (odds ratio (OR), 3.036; 95% confidence interval (CI), 1.078-8.444; p = 0.036). Conclusion Our results suggest that neurologic complications develop in 22.7% of heart transplant recipients admitted to the ICU, and half of them are seen after six months postoperatively. PRES was the most frequent (27.3%) neurologic complication. The risk of neurologic complications is three times higher for males. The mean length of hospital stay and incidence of sepsis were significantly higher in heart transplant recipients who developed neurologic complications.

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.

Neurological Complications in Patients with Heart Transplantation

Neurological complications after heart transplantation are common and include cerebrovascular events (ischemic strokes, hemorrhagic strokes, and transient ischemic attacks), seizures, encephalopathy, central nervous system (CNS) infections, malignancies, and peripheral nervous system complications. Although most neurological complications are transient, strokes and CNS infections can result in high mortality and morbidity. Early recognition and timely management of these serious complications are crucial to improve survival and recovery. Diagnosing CNS infections can be challenging because their clinical presentation can be subtle in the setting of immunosuppression. Immunosuppressive medications themselves can cause a broad spectrum of neurological complications including seizures and posterior reversible encephalopathy syndrome. This article provides a review of the diagnosis and management of neurological complications after cardiac transplantation.

Canadian Cardiovascular Society/Canadian Cardiac Transplant Network Position Statement on Heart Transplantation: Patient Eligibility, Selection, and Post-Transplantation Care

Significant practice-changing developments have occurred in the care of heart transplantation candidates and recipients over the past decade. This Canadian Cardiovascular Society/Canadian Cardiac Transplant Network Position Statement provides evidence-based, expert panel recommendations with values and preferences, and practical tips on: (1) patient selection criteria; (2) selected patient populations; and (3) post transplantation surveillance. The recommendations were developed through systematic review of the literature and using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. The evolving areas of importance addressed include transplant recipient age, frailty assessment, pulmonary hypertension evaluation, cannabis use, combined heart and other solid organ transplantation, adult congenital heart disease, cardiac amyloidosis, high sensitization, and post-transplantation management of antibodies to human leukocyte antigen, rejection, cardiac allograft vasculopathy, and long-term noncardiac care. Attention is also given to Canadian-specific management strategies including the prioritization of highly sensitized transplant candidates (status 4S) and heart organ allocation algorithms. The focus topics in this position statement highlight the increased complexity of patients who undergo evaluation for heart transplantation as well as improved patient selection, and advances in post-transplantation management and surveillance that have led to better long-term outcomes for heart transplant recipients.

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.

Long-term outcomes and management of the heart transplant recipient

Cardiac transplantation remains the gold standard in the treatment of advanced heart failure. With advances in immunosuppression, long-term outcomes continue to improve despite older and higher risk recipients. The median survival of the adult after heart transplantation is currently 10.7 years. While early graft failure and multiorgan system dysfunction are the most important causes of early mortality, malignancy, rejection, infection, and cardiac allograft vasculopathy contribute to late mortality. Chronic renal dysfunction is common after heart transplantation and occurs in up to 68% of patients by year 10, with 6.2% of patients requiring dialysis and 3.7% undergoing renal transplant. Functional outcomes after heart transplantation remain an area for improvement, with only 26% of patients working at 1-year post-transplantation, and are likely related to the high incidence of depression after cardiac transplantation. Areas of future research include understanding and managing primary graft dysfunction and reducing immunosuppression-related complications.

Clinical Characteristics of Transplant-associated Encephalopathy in Children

We aimed to analyze characteristics of encephalopathy after both hematopoietic stem cell and solid organ pediatric transplantation. We retrospectively reviewed medical records of 662 pediatric transplant recipients (201 with liver transplantation [LT], 55 with heart transplantation [HT], and 67 with kidney transplantation [KT], 339 with allogeneic hematopoietic stem cell transplantation [HSCT]) who received their graft organs at Asan Medical Center between January 2000 and July 2014. Of the 662 patients, 50 (7.6%) experienced encephalopathy after transplantation. The incidence of encephalopathy was significantly different according to the type of organ transplant: LT, 16/201 (8.0%), HT, 13/55 (23.6%), KT, 5/67 (7.5%), and HSCT, 16/339 (4.7%) (P < 0.001). Drug-induced encephalopathy (n = 14) was the most common encephalopathy for all transplant types, but particularly after HSCT. Hypertensive encephalopathy was the most common after KT and HT, whereas metabolic encephalopathy was the most common after LT. The median time to encephalopathy onset also differed according to the transplant type: 5 days after KT (range 0-491 days), 10 days after HT (1-296 days), 49.5 days after HSCT (9-1,405 days), and 39 days after LT (1-1,092 days) (P = 0.018). The mortality rate among patients with encephalopathy was 42.0% (n = 21/50). Only 5 patients died of neurologic complications. Transplant-associated encephalopathy presented different characteristics according to the type of transplant. Specialized diagnostic approach for neurologic complications specific to the type of transplant may improve survival and quality of life in children after transplantation.

Ischemic Stroke after Heart Transplantation

Cerebrovascular complications after orthotopic heart transplantation (OHT) are more common in comparison with neurological sequelae subsequent to routine cardiac surgery. Ischemic stroke and transient ischemic attack (TIA) are more common (with an incidence of up to 13%) than intracranial hemorrhage (2.5%). Clinically, ischemic stroke is manifested by the appearance of focal neurologic deficits, although sometimes a stroke may be silent or manifests itself by the appearance of encephalopathy, reflecting a diffuse brain disorder. Ischemic stroke subtypes distribution in perioperative and postoperative period after OHT is very different from classical distribution, with different pathogenic mechanisms. Infact, ischemic stroke may be caused by less common and unusual mechanisms, linked to surgical procedures and to postoperative inflammation, peculiar to this group of patients. However, many strokes (40%) occur without a well-defined etiology (cryptogenic strokes). A silent atrial fibrillation (AF) may play a role in pathogenesis of these strokes and P wave dispersion may represent a predictor of AF. In OHT patients, P wave dispersion correlates with homocysteine plasma levels and hyperhomocysteinemia could play a role in the pathogenesis of these strokes with multiple mechanisms increasing the risk of AF. In conclusion, stroke after heart transplantation represents a complication with considerable impact not only on mortality but also on subsequent poor functional outcome.

Relationship Between Cerebral Blood Flow and Blood Pressure in Long-Term Heart Transplant Recipients

Heart transplant recipients are at an increased risk for cerebral hemorrhage and ischemic stroke; yet, the exact mechanism for this derangement remains unclear. We hypothesized that alterations in cerebrovascular regulation is principally involved. To test this hypothesis, we studied cerebral pressure-flow dynamics in 8 clinically stable male heart transplant recipients (62±8 years of age and 9±7 years post transplant, mean±SD), 9 male age-matched controls (63±8 years), and 10 male donor controls (27±5 years). To increase blood pressure variability and improve assessment of the pressure-flow dynamics, subjects performed squat–stand maneuvers at 0.05 and 0.10 Hz. Beat-to-beat blood pressure, middle cerebral artery velocity, and end-tidal carbon dioxide were continuously measured during 5 minutes of seated rest and throughout the squat–stand maneuvers. Cardiac baroreceptor sensitivity gain and cerebral pressure-flow responses were assessed with linear transfer function analysis. Heart transplant recipients had reductions in R-R interval power and baroreceptor sensitivity low frequency gain ( P <0.01) compared with both control groups; however, these changes were unrelated to transfer function metrics. Thus, in contrast to our hypothesis, the increased risk of cerebrovascular complication after heart transplantation does not seem to be related to alterations in cerebral pressure-flow dynamics. Future research is, therefore, warranted.

Neurologic aspects of heart transplantation

Cardiac transplantation remains the best treatment option for patients with end-stage, NYHA class IV heart failure who have failed conventional therapy. However, transplant rates have remained static largely due to limited organ donor supplies. Therefore, appropriate allocation of this precious resource is critical to maximize benefit, both at a patient level and at a societal level. Neurologic diseases, such as cerebrovascular disease and peripheral neuropathy, are prevalent in this patient population, as the major risk factors for heart disease place patients at risk for neurologic disease as well. Examples include hypertension, smoking, hypercholesterolemia, obesity, and diabetes. Pretransplant neurologic evaluation is very important to identify conditions that may limit survival after cardiac transplantation. In general, systemic diseases exacerbated by immunosuppression, conditions limiting ability to rehabilitate, and dementias are considered contraindications. Post-transplant neurologic complications are divided into central versus peripheral, and early versus late. The most common early complication is ischemic stroke. Other serious complications include hemorrhagic stroke, encephalopathy, and critical illness neuropathy. Over the long term, post-transplant immunosuppressive regimens are considered "a double edged sword." Although immunosuppressive medications are critical to preventing rejection and allograft dysfunction, they do have significant risk of morbidity and mortality associated with them, including neurologic side-effects. These include: (1) drug toxicities, such as lowering of seizure thresholds; (2) encephalopathy, such as posterior reversible encephalopathy syndrome (PRES); (3) infections; (4) malignancies, such as post-transplant lymphoproliferative disorder (PTLD). Many of the same considerations discussed in adult heart transplant recipients apply to pediatric heart transplant recipients as well. In children, seizures are the most common neurologic complication, although other neurologic complication rates are comparable.

[Neurological aspects of chronic heart failure]

Chronic heart failure (CHF) is one of the leading causes of hospitalization, morbidity and mortality. Moreover, there is a high rate of neurological as well as neuropsychological comorbidities, namely ischemic stroke, structural brain alterations, cognitive impairment, sleep apnea and possible side-effects of HF medication such as delirium or (intracerebral) hemorrhage. The higher stroke risk in patients with HF increases further with age, concomitant arterial hypertension or atrial fibrillation (AF). In women the stroke risk increases with reduced ejection fraction (EF). In general stroke in HF patients is associated with a poor outcome and higher mortality, which is increased more than 2-fold. Furthermore, approximately 25-80% of all patients with CHF experience cognitive impairments such as decreased attention and concentration, memory loss, diminished psychomotor reaction time and decreased executive functions. Cognitive impairment in patients with HF has been linked to losses in gray matter, (silent) ischemic strokes, decreased cerebral perfusion and higher mortality. Moreover, sleep apnea occurs in more than half of all patients with CHF and reduced EF. However, prospective studies are needed to test whether early detection and optimal treatment of HF reduces the burden of neurological and neuropsychological sequelae.

Antithrombotic medication for cardioembolic stroke prevention

Embolism of cardiac origin accounts for about 20% of ischemic strokes. Nonvalvular atrial fibrillation is the most frequent cause of cardioembolic stroke. Approximately 1% of population is affected by atrial fibrillation, and its prevalence is growing with ageing in the modern world. Strokes due to cardioembolism are in general severe and prone to early recurrence and have a higher long-term risk of recurrence and mortality. Despite its enormous preventive potential, continuous oral anticoagulation is prescribed for less than half of patients with atrial fibrillation who have risk factors for cardioembolism and no contraindications for anticoagulation. Available evidence does not support routine immediate anticoagulation of acute cardioembolic stroke. Anticoagulation therapy's associated risk of hemorrhage and monitoring requirements have encouraged the investigation of alternative therapies for individuals with atrial fibrillation. New anticoagulants being tested for prevention of stroke are low-molecular-weight heparins (LMWH), unfractionated heparin, factor Xa inhibitors, or direct thrombin inhibitors like dabigatran etexilate and rivaroxaban. The later exhibit stable pharmacokinetics obviating the need for coagulation monitoring or dose titration, and they lack clinically significant food or drug interaction. Moreover, they offer another potential that includes fixed dosing, oral administration, and rapid onset of action. There are several concerns regarding potential harm, including an increased risk for hepatotoxicity, clinically significant bleeding, and acute coronary events. Therefore, additional trials and postmarketing surveillance will be needed.

Cerebrovascular complications after heart transplantation

Neurological complications in orthotopic heart transplantation represent a major cause of morbidity and mortality despite successful transplantation. The most frequent perioperative neurological complications are delirium or encephalopathy. In this period cerebrovascular complication ranges between 5-11%. After the perioperative period, the 5-year stroke risk after cardiac transplantation is 4.1%. In a retrospective study conducted with 314 patients who underwent cardiac transplantation, it was found that 20% of cerebrovascular complications occurred within the first two weeks after transplantation, while 80% occurred in the late postoperative phase. Of these, ischemic stroke is the most common subtype. In the perioperative periode, hemodynamic instability, cardiac arrest, extracorporeal circulation over 2 hours, prior history of stroke, and carotid stenosis greater than 50% have been reported to be risk factors for the occurrence of cerebrovascular complications. Perioperative cerebrovascular complications are associated with higher mortality and poor functional outcome at one year follow-up.After the perioperative period, the only factor that has been significantly associated with an increased risk of cerebrovascular complications is a history of prior stroke, either ischemic or hemorrhagic. Other associated factors include unknown atrial fibrillation, septic emboli from endocarditis, cardiac catheterization and perioperative hemodynamic shock. According to the TOAST etiologic classification, the most prevalent etiologic subtype of ischemic stroke is undetermined cause.

Interobserver agreement in the trial of org 10172 in acute stroke treatment classification of stroke based on retrospective medical record review

BACKGROUND

The reliability of the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification system of stroke in siblings of stroke-affected probands has not been tested. Similarly, the reliability of using clinical medical records to classify ischemic stroke has not been assessed. The purpose of this study was to establish the interrater reliability of sibling stroke subtyping by applying the TOAST criteria to retrospectively obtained medical records.

METHODS

Thirty medical records were randomly sampled from among the records of all siblings previously classified as stroke affected by the Siblings with Ischemic Stroke Study (SWISS) Stroke Verification Committee. Blinded medical records for these individuals were sent to 6 physician reviewers who independently classified TOAST stroke subtype on the basis of record review.

RESULTS

Using the kappa statistic to assess interrater reliability, the overall reliability (SE) for assigning a TOAST subtype of stroke was 0.54 (0.03). Pair-wise comparisons between the original SWISS Stroke Verification Committee diagnoses and the diagnoses made by other reviewers exhibited moderate reliability (kappa range 0.41-0.56). The kappa statistics for common stroke subtypes were large vessel, 0.80 (0.06); cardioembolic, 0.80 (0.06); small vessel, 0.53 (0.06); and unknown cause, 0.40 (0.06).

CONCLUSION

We conclude that TOAST subtyping had moderate interrater reliability. Large-artery and cardioembolic subtype diagnoses seemed most reliable.