Frequency and significance of conduction defects early after orthotopic heart transplantation

Impact of controlled hypothermic preservation on outcomes following heart transplantation

BACKGROUND

Severe primary graft dysfunction (PGD) is a major cause of early mortality after heart transplant, but the impact of donor organ preservation conditions on severity of PGD and survival has not been well characterized.

METHODS

Data from US adult heart-transplant recipients in the Global Utilization and Registry Database for Improved Heart Preservation-Heart Registry (NCT04141605) were analyzed to quantify PGD severity, mortality, and associated risk factors. The independent contributions of organ preservation method (traditional ice storage vs controlled hypothermic preservation) and ischemic time were analyzed using propensity matching and logistic regression.

RESULTS

Among 1,061 US adult heart transplants performed between October 2015 and December 2022, controlled hypothermic preservation was associated with a significant reduction in the incidence of severe PGD compared to ice (6.6% [37/559] vs 10.4% [47/452], p = 0.039). Following propensity matching, severe PGD was reduced by 50% (6.0% [17/281] vs 12.1% [34/281], respectively; p = 0.018). The Kaplan-Meier terminal probability of 1-year mortality was 4.2% for recipients without PGD, 7.2% for mild or moderate PGD, and 32.1%, for severe PGD (p < 0.001). The probability of severe PGD increased for both cohorts with longer ischemic time, but donor hearts stored on ice were more likely to develop severe PGD at all ischemic times compared to controlled hypothermic preservation.

CONCLUSIONS

Severe PGD is the deadliest complication of heart transplantation and is associated with a 7.8-fold increase in probability of 1-year mortality. Controlled hypothermic preservation significantly attenuates the risk of severe PGD and is a simple yet highly effective tool for mitigating post-transplant morbidity.

A Paradigm Shift in Heart Preservation: Improved Post-transplant Outcomes in Recipients of Donor Hearts Preserved With the SherpaPak System

Traditional ice storage has been the historic standard for preserving donor's hearts. However, this approach provides variability in cooling, increasing risks of freezing injury. To date, no preservation technology has been reported to improve survival after transplantation. The Paragonix SherpaPak Cardiac Transport System (SCTS) is a controlled hypothermic technology clinically used since 2018. Real-world evidence on clinical benefits of SCTS compared to conventional ice cold storage (ICS) was evaluated. Between October 2015 and January 2022, 569 US adults receiving donor hearts preserved and transported either in SCTS (n = 255) or ICS (n = 314) were analyzed from the Global Utilization And Registry Database for Improved heArt preservatioN (GUARDIAN-Heart) registry. Propensity matching and a subgroup analysis of >240 minutes ischemic time were performed to evaluate comparative outcomes. Overall, the SCTS cohort had significantly lower rates of severe primary graft dysfunction (PGD) ( p = 0.03). When propensity matched, SCTS had improving 1-year survival ( p = 0.10), significantly lower rates of severe PGD ( p = 0.011), and lower overall post-transplant MCS utilization ( p = 0.098). For patients with ischemic times >4 hours, the SCTS cohort had reduced post-transplant MCS utilization ( p = 0.01), reduced incidence of severe PGD ( p = 0.005), and improved 30-day survival ( p = 0.02). A multivariate analysis of independent risk factors revealed that compared to SCTS, use of ice results in a 3.4-fold greater chance of severe PGD ( p = 0.014). Utilization of SCTS is associated with a trend toward increased post-transplant survival and significantly lower severe PGD and MCS utilization. These findings fundamentally challenge the decades-long status quo of transporting donor hearts using ice.

Review of Postoperative Care for Heart Transplant Recipients

The early postoperative management strategies after heart transplantation include optimizing the function of the denervated heart, correcting the causes of hemodynamic instability, and initiating and maintaining immunosuppressive therapy, allograft rejection surveillance, and prophylaxis against infections caused by immunosuppression. The course of postoperative support is influenced by the quality of allograft myocardial protection prior to implantation and reperfusion, donor-recipient heart size matching, surgical technique of orthotopic heart transplantation, and patient factors (eg, preoperative condition, immunologic compatibility, postoperative vasomotor tone, severity and reversibility of pulmonary vascular hypertension, pulmonary function, mediastinal blood loss, and end-organ perfusion). This review provides an overview of the early postoperative care of recipients and includes a brief description of the surgical techniques for orthotopic heart transplantation.

Newly acquired complete right bundle branch block early after heart transplantation is associated with lower survival

Aims

Right bundle branch block (RBBB) after heart transplantation (HTX) is a common finding, but its impact on post‐transplant survival remains uncertain. This study investigated the post‐transplant outcomes of patients with complete RBBB (cRBBB) ≤ 30 days after HTX.

Methods

This registry study analysed 639 patients receiving HTX at Heidelberg Heart Center between 1989 and 2019. Patients were stratified by diagnosis of cRBBB ≤ 30 days after HTX. Analysis included recipient and donor data, medication, echocardiographic features, graft rejections, atrial fibrillation, heart rates, permanent pacemaker implantation and mortality after HTX including causes of death.

Results

One hundred thirty‐nine patients showed cRBBB ≤ 30 days after HTX (21.8%), 20 patients with pre‐existing cRBBB in the donor heart (3.2%) and 119 patients with newly acquired cRBBB (18.6%). Patients with newly acquired cRBBB had a worse 1‐year post‐transplant survival (36.1%, P < 0.01) compared with patients with pre‐existing cRBBB (85.0%) or without cRBBB (86.4%), along with a higher percentage of death due to graft failure (P < 0.01). Multivariate analysis indicated cRBBB ≤ 30 days after HTX as significant risk factor for 1‐year mortality after HTX (HR: 2.20; 95% CI: 1.68–2.87; P < 0.01). Secondary outcomes showed a higher rate of an enlarged right atrium (P = 0.01), enlarged right ventricle (P < 0.01), reduced right ventricular function (P < 0.01), 30‐day atrial fibrillation (P < 0.01) and 1‐year permanent pacemaker implantation (P = 0.02) in patients with cRBBB after HTX.

Conclusions

Newly acquired cRBBB early after HTX is associated with increased post‐transplant mortality.

Association of Newly Developed Right Bundle Branch Block with Graft Rejection Following Heart Transplantation

PURPOSE

We aimed to examine associations between right bundle branch block (RBBB) following heart transplantation (HT) and graft rejection.

MATERIALS AND METHODS

We investigated 51 patients who underwent endomyocardial biopsies, electrocardiogram, right-side cardiac catheterization, and echocardiography at 1 month and 1 year after HT. We classified patients into four groups according to the development of RBBB, based on electrocardiogram at 1 month and 1 year: 1) sustained RBBB, 2) disappeared RBBB, 3) newly developed RBBB, and 4) sustained non-RBBB. The RBBB was defined as an RSR' pattern in V1 with a QRS duration ≥100 ms on electrocardiogram.

RESULTS

The newly developed RBBB group (n=13, 25.5%) had a higher rate of new onset graft rejection (from grade 0 to grade ≥1R, 30.8% vs. 10.0% vs. 21.4%, p=0.042) at 1 year, compared with sustained RBBB (n=10, 19.6%) and sustained non-RBBB group (n=28, 54.9%). In contrast, the incidence of resolved graft rejection (from grade ≥1R to grade 0) was higher in the sustained RBBB group than the newly developed RBBB and sustained non-RBBB groups (70.0% vs. 7.7% vs. 25.0%, p=0.042). Left atrial volume index was significantly higher in the newly developed RBBB group than the sustained RBBB and sustained non-RBBB groups (60.6±25.9 mL/m² vs. 36.0±11.0 mL/m² vs. 38.4±18.1 mL/m², p=0.003).

CONCLUSION

Close monitoring for new development of RBBB at 1 year after HT, which was associated with a higher incidence of new onset graft rejection, may be helpful to identify high risk patients for graft rejection.

Electrocardiographic abnormalities in the first year after heart transplantation

STUDY AIM

Describe ECG abnormalities in the first year following transplant surgery.

METHODS

Analysis of 12-lead ECGs from heart transplant subjects enrolled in an ongoing multicenter clinical trial.

RESULTS

585 ECGs from 98 subjects showed few with abnormal cardiac rhythm (99% of ECGs were sinus rhythm/tachycardia). A majority of subjects (69%) had either right intraventricular conduction delay (56%) or right bundle branch block (13%). A second prevalent ECG abnormality was atrial enlargement (64% of subjects) that was more commonly left atrial (55%) than right (30%).

CONCLUSIONS

Right intraventricular conduction delay or right bundle branch block is prevalent in heart transplant recipients in the first year following transplant surgery. Whether this abnormality is related to acute allograph rejection or endomyocardial biopsy procedures is the subject of the ongoing clinical trial. Atrial enlargement ECG criteria (especially, left atrial) are also common and are likely due to transplant surgery with subsequent atrial remodeling.

Bidirectional ventricular tachycardia due to coronary allograft vasculopathy a unique presentation

Bidirectional ventricular tachycardia (BVT) is an uncommon type of polymorphic ventricular tachycardia (PVT) with alternating polarity of the QRS complex most commonly described digitalis toxicity. Recent data has demonstrated the possible molecular basis of this electrocardiographic phenomenon. To our knowledge this is the first reported case of BVT in a patient with orthotopic cardiac transplantation and coronary allograft vasculopathy.

The Preoperative Evaluation of the Transplanted Patient for Nontransplant Surgery

With the improved success of solid-organ transplantation, there has been an increased willingness to transplant individuals previously felt to be unsuitable for such procedures. Factors such as age and various medical comorbidities are no longer considered contraindications to transplantation, and hence, an increasing number of recipients may require medical care not specifically related to the transplant. After transplantation, many of these patients may require elective or emergent surgery, making it important for all surgeons to be familiar with the factors that may influence surgical outcomes in this population, asa well asa factors that affect postoperative care. Most transplant centres use a team approach to manage these complex patients, relying on medical professionals experienced in their care and management. Close interaction with the transplant team is likely the single most important step in preparing the transplanted patient for surgery and managing their postoperative care.

Arrhythmias after orthotopic heart transplantation

BACKGROUND

Arrhythmias frequently occur after orthotopic heart transplantation (OHT).

METHODS AND RESULTS

The most common are ventricular premature complexes, atrial premature complexes, sinus or junctional bradycardia, atrial fibrillation, and atrial flutter, all of which have varying clinical significance depending on associated or causative conditions. Unique etiologic factors such as allograft rejection, transplant coronary artery disease, and altered anatomy and autonomic nervous system changes require that arrhythmias be treated differently after OHT compared with the general population.

CONCLUSION

The potentially severe ramifications of allograft rejection and coronary artery disease make treatment of these disorders in the setting of arrhythmias as important as treating the arrhythmias themselves. At the same time, autonomic denervation and altered anatomy after transplantation complicate drug and device therapies.

Postbypass arrhythmias: pathophysiology, prevention, and therapy

PURPOSE OF REVIEW

To review the medical literature on new-onset arrhythmias after cardiac bypass surgery in adults, focusing on the most recent advances on this topic.

RECENT FINDINGS

Main attention is focused on possible predictors and prevention of postoperative atrial fibrillation, because this arrhythmia is the most common type encountered with cardiac surgery and is associated with increased morbidity and mortality and longer, more expensive hospital stays. Therapeutic management of atrial fibrillation favors class III antiarrhythmic agents like amiodarone and sotalol. Direct-current cardioversion proved to be an ineffective method for treatment of supraventricular tachyarrhythmias. In patients with persistent atrioventricular block or sinus node dysfunction after cardiac valve surgery, a risk score to predict the need for permanent pacing after cardiac valve surgery was developed. This scoring system may be useful for pre- and perioperative management of patients undergoing cardiac valve surgery.

SUMMARY

Recent studies demonstrate a continued effort to improve our knowledge about postbypass arrhythmias. New insights in the pathophysiology of postoperative cardiac arrhythmias and advances in prevention and therapy are rapid and results are heterogeneous, so it is difficult for the clinician to keep abreast with these new findings.

Long-term follow-up of arrhythmias in pediatric orthotopic heart transplant recipients: incidence and correlation with rejection

BACKGROUND

Arrhythmias in adult orthotopic heart transplant (OHT) recipients are common and have been used as predictors of rejection. Because of the paucity of information in pediatric OHT recipients, the purpose of this study was to determine the incidence and correlation of arrhythmias with rejection or with coronary artery disease (CAD) in children.

METHODS

We retrospectively reviewed the records, electrocardiograms (ECGs), and 24-hour ambulatory ECGs of patients who underwent OHT from January 1984 to December 1999. We excluded arrhythmias occurring in the first 2 weeks after OHT.

RESULTS

Sixty-nine patients underwent OHT, received triple-immunosuppression therapy, were discharged home, and have been followed for a mean of 4.7 years (0.3-13 years). Each patient had an average of 10 ECGs and three 24-hour ECGs. Twenty-six patients had 33 arrhythmias: sinus bradycardia (n = 9), atrial tachycardia (n = 9), ventricular tachycardia (n = 3), and Wenckebach periodicity (n = 6). Sinus bradycardia was treated with theophylline in 8 patients, and 2 required pacemakers. Atrial tachycardias (atrial flutter in 4 patients and atrial ectopic tachycardia in 5) were treated with digoxin, propranolol, or procainamide. Ventricular tachycardia was treated with mexiletine, lidocaine, and amiodarone. There were 65 episodes of rejection, 20 of which were moderate/severe (> or =3B). Only Wenckebach was associated with the presence of either rejection or CAD (p < 0.05).

CONCLUSIONS

We noted clinically significant arrhythmias in 38% of the pediatric OHT recipients. Sinus bradycardia, atrial tachyarrhythmias, and ventricular tachycardia occurred with the same frequency. Only new-onset Wenckebach periodicity was noted in the presence of either CAD or rejection. No arrhythmia was of negative predictive value for rejection or CAD. From this data, we suggest that new-onset Wenckebach prompt evaluation for rejection or CAD.

Histologic findings in the conduction system after cardiac transplantation and correlation with electrocardiographic findings

The study of the sinus node and the specialized atrioventricular junction by serial sections in cardiac transplantation revealed that acute rejection involving the conduction system was equally severe as the working myocardium, with the exception of the His bundle. During acute rejection, the sudden appearance of a first-degree atrioventricular block may suggest severe involvement of the conduction system with impending cardiac arrest.

Incidence and prognostic value of electrocardiographic abnormalities after heart transplantation

BACKGROUND

The improvement of surgical techniques and the use of immunosuppressive drugs within the past 15 years has made heart transplantation an increasingly performed procedure and an accepted treatment for end-stage cardiac failure.

HYPOTHESIS

The aim of this study was to describe the changes of the 12-lead electrocardiogram (ECG) after heart transplantation and to determine their prognostic value on complications such as rejection or graft coronary artery disease during follow-up.

METHODS

The ECGs of 62 consecutive patients were analyzed for 5 years at follow-up periods of 1, 2, 3, 6 months and yearly after transplantation.

RESULTS

The most prevalent abnormality was the presence of complete or incomplete right bundle-branch block (RBBB). New RBBB appeared in 69% (43/62) of the patients, mainly during the first month (21/43). There was no left bundle-branch block. We detected nine episodes of supraventricular arrhythmias: one atrial fibrillation, six atrial flutter, one junctional tachycardia, one orthodromic tachycardia on a Wolff-Parkinson-White syndrome; all appearing during the first 3 months. Three of the six episodes of atrial flutter occurred during an episode of acute rejection. There was no relation between RBBB and the gender and age of recipients and donors, nor with the graft ischemic time and the pretransplantation hemodynamic values. Right bundle-branch block was not associated with acute rejection nor with graft coronary artery disease.

CONCLUSION

The ECG abnormalities after heart transplantation have no predictive value on the long-term evolution. Right bundle-branch block is very frequent and is not associated with adverse prognosis.

Natural history, determinants, and clinical relevance of conduction abnormalities following orthotopic heart transplantation

To study the long-term evolution, determinants, and clinical relevance of the conduction abnormalities after orthotopic heart transplantation, 87 patients, followed for a mean of 105 +/- 72 weeks, were divided into 3 groups according to the characteristics of their electrocardiograms compared with their initial electrocardiogram recorded at study entry. The first group consisted of 24 patients whose initial electrocardiogram was normal, and subsequent electrocardiograms remained normal throughout the study. The second group included 27 patients who developed electrocardiographic evidence of progressive conduction system damage. The third group comprised 36 patients whose initial electrocardiogram was abnormal and subsequent electrocardiograms remained unchanged during follow-up. Although the hemodynamic and echocardiographic evaluation of right and left ventricular function were initially similar among the 3 groups, groups 2 and 3 demonstrated a significant deterioration of left ventricular ejection fraction (62 +/- 12% to 55 +/- 16% and 62 +/- 8% to 57 +/- 14%, respectively; p < 0.05) and cardiac index (2.7 +/- 0.6 to 2.3 +/- 0.5 and 3.0 +/- 0.9 to 2.5 +/- 0.9 L/min/m2, respectively; p < 0.05) while patients in group 1 maintained their normal baseline indices. Incidence and progression of coronary artery disease, as well as frequency of rejection episodes, were comparable among the groups. Mortality was higher in the 2 groups with evidence of conduction defects. Sudden death associated with complete heart block (2 patients) or ventricular arrhythmias (3 patients) was exclusively confined to patients with evidence of progressive electrocardiogram abnormalities. We conclude that, following orthotopic heart transplantation, stable or progressive conduction system damage on the electrocardiogram is associated with left ventricular dysfunction and increased mortality. Sudden death is not uncommon among patients demonstrating worsening cardiac conduction and, in some cases, is related to the development of potentially preventable complete heart block.

Noninvasive diagnosis of cardiac allograft rejection: the effect of procainamide

The surface electrocardiogram (ECG) has been used as a noninvasive technique for the diagnosis of cardiac allograft rejection. Alteration in conduction, R-wave amplitude, and rhythm have been associated with rejection. These ECG findings are modulated by the myocyte sodium channel, but are inconsistent and occur only during severe rejection episodes. The purpose of this study was to (1) characterize changes in cardiac electrophysiology during allograft rejection using the highly sensitive intramyocardial electrocardiogram and (2) determine whether pharmacological sodium channel blockade with procainamide enhances subtle ECG changes. Nine mongrel dogs underwent heterotopic heart transplantation in which four intramyocardial leads (one anteriorly and posteriorly on each ventricle) were attached. Leads exited to a subcutaneously placed ECG block which was transcutaneously accessed posttransplant to record direct intramyocardial electrocardiograms. Six animals were treated with procainamide, while three were not and served as controls. Daily measurements included the QRS, QT, and QTc intervals and the R-wave amplitude. Endomyocardial biopsies were performed weekly and also when significant decline in ECG amplitude occurred. Detailed ECG interval analysis failed to establish any correlation between conduction and rejection, even in the procainamide-treated group. Intramyocardial amplitude analysis, however, had a sensitivity of 100% and a specificity of 86% for the diagnosis of rejection. The results indicate that intramyocardial ECG interval analysis is not predictive of rejection even when prolonging conduction with procainamide. Amplitude analysis, however, remains an accurate noninvasive means for the early detection of cardiac allograft rejection and should allow more selective use of endomyocardial biopsy.

Electrocardiographic and electrophysiologic properties of cardiac allografts

The increasing number of heart transplant patients requires that physicians be able to recognize the electrocardiographic (ECG) and electrophysiologic properties of cardiac allografts. Cardiac allografts are characterized by modifications of resting ECGs and frequent arrhythmias in the postoperative period, and the loss of autonomic nervous control illustrated by permanent tachycardia and loss of heart rate variability during 24-hour ambulatory ECG recording. Some clinical and experimental observations suggest a mid-term reinnervation of the cardiac allograft, but this requires histologic confirmation. The electrophysiologic characteristics of the denervated myocardium are similar to those of the innervated myocardium at rest. However, supersensitivity to circulating catecholamines has been observed in cardiac allografts as in experimentally denervated hearts, which is responsible for a progressive increase in heart rate during exercise and a slow decrease during recovery. Supersensitivity of the denervated heart to acetylcholine may explain the high prevalence of donor sinus dysfunction due to impairment of its automaticity. More often, the sinus node dysfunction is transient and can be treated with an adenosine antagonist, such as theophylline, before permanent implantation of a pacemaker. In the case of pacemaker implantation, synchronization of the donor atria with the recipient atria is desirable, and an endocardial lead implantation is preferred. Several electrophysiologic changes have been observed during acute cardiac allograft rejection. From experimental studies, the most important of these are the disturbance of conduction in the atria and the atrioventricular node and a decrease in the amplitude of the ventricular potential. Initial studies on isolated myocytes show profound changes in membrane conductance during experimental cardiac rejection. The development of new noninvasive detection methods of cardiac allograft rejection, such as intramyocardial voltage electrogram monitoring and high-resolution ECG, could help early diagnosis.