The evolving risk of sudden cardiac death after heart transplant. An analysis of the ISHLT Thoracic Transplant Registry

ACC/AHA/ASE/HFSA/HRS/SCAI/SCCT/SCMR 2025 Appropriate Use Criteria for Implantable Cardioverter-Defibrillators, Cardiac Resynchronization Therapy, and Pacing

This appropriate use criteria (AUC) document is developed by the American College of Cardiology along with key specialty and subspecialty societies. It provides a comprehensive review of common clinical scenarios where implantable cardioverter-defibrillator (ICD), cardiac resynchronization therapy (CRT), cardiac contractility modulation, leadless pacing, and conduction system pacing therapies are frequently considered. The 335 clinical scenarios covered in this document address ICD indications including those related to secondary prevention, primary prevention, comorbidities, generator replacement at elective replacement indicator, dual-chamber, and totally subcutaneous ICDs, as well as device indications related to CRT, conduction system pacing, leadless pacing, cardiac contractility modulation, and ICD therapy in the setting of left ventricular assist devices (LVADs).

The indications (clinical scenarios) were derived from common applications or anticipated uses, as well as from current clinical practice guidelines and results of studies examining device implantation. The indications in this document were developed by a multidisciplinary writing group and scored by a separate independent rating panel on a scale of 1 to 9 to designate care that is considered “Appropriate” (median 7 to 9), “May Be Appropriate” (median 4 to 6), and “Rarely Appropriate” (median 1 to 3). The final ratings reflect the median score of the 17 rating panel members.

In general, Appropriate designations were assigned to scenarios for which clinical trial evidence and/or clinical experience was available that supported device implantation. In contrast, scenarios for which clinical trial evidence was limited or device implantation seemed reasonable for extenuating or practical reasons were categorized as May Be Appropriate. Scenarios for which there were data showing harm, or no data were available, and medical judgment deemed device therapy was illadvised were categorized as Rarely Appropriate. For example, comorbidities including reduced life expectancy related to noncardiac conditions or severe cognitive dysfunction would negatively impact appropriateness ratings.

The appropriate use criteria for ICD, CRT, and pacing have the potential to enhance clinician decision making, healthcare delivery, and payment policy. Furthermore, recognition of clinical scenarios rated as May Be Appropriate facilitates the identification of areas where there may be gaps in evidence that would benefit from future research.

The American College of Cardiology (ACC) has a long history of developing documents (eg, expert consensus decision pathways, health policy statements, AUC documents) to provide members with guidance on both clinical and nonclinical topics relevant to cardiovascular care. In most circumstances, these documents have been created to complement clinical practice guidelines and to inform clinicians about areas where evidence is new and evolving or where sufficient data are more limited. Despite this, numerous gaps persist, highlighting the need for more streamlined and efficient processes to implement best practices in patient care.

Central to the ACC’s strategic plan is the generation of actionable knowledge —a concept that places emphasis on making clinical information easier to consume, share, integrate, and update. To this end, the ACC has shifted from developing isolated documents to creating integrated “solution sets.” These are groups of closely related activities, policy, mobile applications, decision-support tools, and other resources necessary to transform care and/or improve heart health. Solution sets address key questions facing care teams and attempt to provide practical guidance to be applied at the point of care. They use both established and emerging methods to disseminate information for cardiovascular conditions and their related management. The success of solution sets rests firmly on their ability to have a measurable impact on the delivery of care. Because solution sets reflect current evidence and ongoing gaps in care, the associated tools will be refined across time to match changing evidence and member needs.

AUC represent a key component of solution sets. They consist of common clinical scenarios associated with given disease states and ratings that define when it is reasonable to perform testing or provide therapies and, importantly, when it is not. AUC methodology relies on content development work groups, which create patient scenarios, and independent rating panels that employ a modified Delphi process to rate the relevant options for testing and intervention as Appropriate, May Be Appropriate, or Rarely Appropriate. AUC should not replace clinician judgment and practice experience but should function as tools to improve patient care and health outcomes in a cost-effective manner.

I extend sincere gratitude to the writing group for their invaluable contributions to the development of this document’s structure and clinical scenarios; to the rating panelists—a distinguished group of professionals with diverse expertise—for their thoughtful deliberation of the merits of device implantation across various clinical contexts; and to the reviewers for their thoughtful evaluation of the clinical scenarios and evidence mapping. Additionally, I am grateful to the members of the Solution Set Oversight Committee, which provided insight and guidance, and to ACC staff members María Velásquez and Lara Gold, for their support in bringing this document to fruition.

Microvascular Resistance Reserve and Prognosis After Heart Transplantation

BACKGROUND

Impaired microcirculatory function after heart transplantation is associated with increased risk for acute cellular rejection. Microvascular resistance reserve (MRR) is a novel index for assessing microcirculatory function, irrespective of epicardial coronary artery stenosis, but it has not been validated in transplanted hearts.

OBJECTIVES

The aim of this study was to investigate the prognostic impact of MRR in heart transplantation.

METHODS

The present study prospectively enrolled 154 heart transplant recipients who underwent scheduled coronary angiography and invasive coronary physiological assessment 1 month after transplantation. Coronary microcirculatory dysfunction was defined as MRR ≤3.0. Elevated microcirculatory resistance was defined as an index of microcirculatory resistance ≥15. The presence of epicardial coronary stenosis was assessed by fractional flow reserve. The primary outcome was a composite of death or biopsy-proven acute cellular rejection of grade ≥ 2R after transplantation.

RESULTS

Among the total patients, 22.1% (34 of 154) had impaired microcirculatory function (MRR ≤3.0), and 77.9% (122 of 154) had preserved microcirculatory function (MRR >3.0). During median follow-up of 730 days (Q1-Q3: 730-730 days), patients with MRR ≤3.0 showed increased risk for a composite of death or acute cellular rejection (adjusted HR: 5.31; 95% CI: 2.65-10.64; P < 0.001), acute cellular rejection (adjusted HR: 4.83; 95% CI: 2.20-10.60; P < 0.001), and death (adjusted HR: 5.19; 95% CI: 1.24-21.62; P = 0.024). MRR was significantly associated with increased risk for death or acute cellular rejection, regardless of epicardial coronary artery stenosis (HR adjusted for fractional flow reserve: 1.89 per 1-U decrease in MRR; 95% CI: 1.46-2.46; P < 0.001) or elevated microcirculatory resistance (HR adjusted for index of microcirculatory resistance: 1.90 per 1-U decrease in MRR; 95% CI: 1.43-2.52; P < 0.001).

CONCLUSIONS

Impaired microcirculatory function, determined by MRR early after heart transplantation, identified patients at high risk for death or acute cellular rejection, regardless of epicardial coronary artery stenosis or elevated microcirculatory resistance. (Physiologic Assessment of Microvascular Function in Heart Transplant Patients; NCT02798731).

Cardiac Implantable Electronic Devices in Cardiac Transplant Patients: A Comprehensive Review

A fraction of patients (approximately 10%) undergoing heart transplantation require permanent pacemaker (PPM) implantation due to sinus node dysfunction or atrioventricular block, occurring either shortly after surgery or later. The incidence of PPM implantation has declined to less than 5% with the introduction of bicaval anastomosis transplantation surgery. Pacing dependency during follow-up varies among recipients. A smaller subset (1.5-3.4%) receives implantable cardioverter-defibrillators (ICDs), but data on their use in transplant recipients are limited, primarily from cohort studies and case series. Sudden cardiac death affects around 10% of transplant recipients, attributed to various nonarrhythmic factors such as acute rejection, late graft failure, and cardiac allograft vasculopathy-induced ischemia. This review offers a comprehensive analysis of the existing data concerning the role of PPMs and ICDs in this population, encompassing leadless PPMs, subcutaneous ICDs, unique considerations, and future directions.

Utility of 64-Slice Coronary Computed Tomography Angiography in Heart Transplant Recipients

BACKGROUND

Graft vasculopathy is a leading cause of death after heart transplantation (HTx). Diagnosing cardiac allograft vasculopathy (CAV) within this patient group poses significant challenges. This study aimed to evaluate the safety and efficacy of coronary computed tomographic angiography (CCTA) in patients after HTx.

METHODS

We enrolled 107 consecutive HTx recipients (26 women, mean age 50 ± 17 years); all were ≥3 years post-HTx with minimal or no evidence of CAV in a prior coronary angiography performed a minimum of 2 years before the current examination. The inclusion criteria comprised an estimated glomerular filtration rate (eGFR) of ≥30, absence of new heart failure symptoms, and no contraindications to iodine contrast or CT scans. All patients underwent a 64-slice CCTA. In cases of minimal or no changes, noninvasive follow-up examinations were conducted. Significant changes in CT prompted additional coronary angiography.

RESULTS

Of the enrolled participants, 9 exhibited minimal changes; 98 displayed no changes in coronary angiography. The median time since transplant was 7 years, with IQR of 4 to 11.25 years. Significant changes were excluded in 98 patients. Among the 9 patients with suspected significant CAV, significant changes were confirmed in 8 patients, resulting in percutaneous transluminal coronary angioplasty (PTCA) performed in 6. One patient from this group died shortly after PTCA. No cardiovascular incidents were observed within the remaining group. The median follow-up period was 539 (IQR = 289-654 days). The mean left ventricular ejection fraction at follow-up was 58% ± 5% compared with 58% ± 4% at baseline. At follow-up, the mean eGFR was 64 ± 18 mL/kg/1.73 m2 compared with the baseline value of 67.2 mL/kg/1.73 m2.

CONCLUSIONS

CCTA appears to offer a secure and efficient means of assessment in HTx recipients.

Perioperative Management of Heart Transplantation: A Clinical Review

In this clinical review, the authors summarize the perioperative management of heart transplant patients with a focus on hemodynamics, immunosuppressive strategies, hemostasis and hemorrage, and the prevention and treatment of infectious complications.

Sudden cardiac death after heart transplantation: a population-based study

AIMS

The epidemiology of sudden cardiac death (SCD) after heart transplantation (HTx) remains imprecisely described. We aimed to assess the incidence and determinants of SCD in a large cohort of HTx recipients, compared with the general population.

METHODS AND RESULTS

Consecutive HTx recipients (n = 1246, 2 centres) transplanted between 2004 and 2016 were included. We prospectively assessed clinical, biological, pathologic, and functional parameters. SCD was centrally adjudicated. We compared the SCD incidence beyond the first year post-transplant in this cohort with that observed in the general population of the same geographic area (registry carried out by the same group of investigators; n = 19 706 SCD). We performed a competing risk multivariate Cox model to identify variables associated with SCD. The annual incidence of SCD was 12.5 per 1,000 person-years [95% confidence interval (CI), 9.7-15.9] in the HTx recipients cohort compared with 0.54 per 1,000 person-years (95% CI, 0.53-0.55) in the general population (P < 0.001). The risk of SCD was markedly elevated among the youngest HTx recipients with standardized mortality ratios for SCD up to 837 for recipients ≤30 years. Beyond the first year, SCD was the leading cause of death. Five variables were independently associated with SCD: older donor age (P = 0.003), younger recipient age (P = 0.001) and ethnicity (P = 0.034), pre-existing donor-specific antibodies (P = 0.009), and last left ventricular ejection fraction (P = 0.048).

CONCLUSION

HTx recipients, particularly the youngest, were at very high risk of SCD compared with the general population. The consideration of specific risk factors may help identify high-risk subgroups.

Change in First-year Intravascular Ultrasound Results Predicts Adverse Events in Heart Transplant Recipients: Implications for Clinical Trial Endpoints

BACKGROUND

Heart transplantation (HTx) is an established therapeutic option for patients with advanced heart failure who are refractory to conventional guideline-directed treatments. This study aimed to reassess whether intravascular ultrasound variables could predict adverse events after HTx in the modern era.

METHODS

One hundred primary HTx recipients with available serial intravascular ultrasound examination results of the left anterior descending artery 4-8 wk and 1 y after HTx were enrolled, with an average follow-up duration of 5.7 y. The primary endpoint was a composite of all-cause death, nonfatal major adverse cardiac events, and angiographic cardiac allograft vasculopathy.

RESULTS

Forty-three patients developed primary endpoints. The baseline maximal intimal thickness was independently associated with the primary endpoint (hazard ratio, 8.24; 95% confidential interval [CI], 3.21-21.21; P  < 0.001), and the optimal cutoff value was 0.64 mm. A change in the plaque atheroma volume in a proximal 20-mm segment from the left anterior descending artery bifurcation >1.05 mm 3 /mm (hazard ratio, 2.75; 95% CI, 1.28-5.89; P  = 0.009) and a change in the first-year maximal intimal thickness >0.27 mm (hazard ratio, 2.63; 95% CI, 1.05-6.56; P  = 0.04) were independent predictors of the primary endpoint 1 y after intravascular ultrasonography.

CONCLUSIONS

The aforementioned important clinical implications of intravascular ultrasound parameters are useful predictors of outcomes, which may be considered endpoints in modern clinical HTx trials.

Risk factors and outcomes of sudden cardiac arrest in pediatric heart transplant recipients

BACKGROUND

Sudden cardiac arrest (SCA) is a prevailing cause of mortality after pediatric heart transplant (HT) but remains understudied. We analyzed the incidence, outcomes, and risk factors for SCA at our center.

METHODS

Retrospective review of all pediatric HT patients at our center from January 1, 2009 to January 1, 2021. SCA was defined as an abrupt loss of cardiac function requiring cardiopulmonary resuscitation and/or mechanical circulatory support (MCS). Events that occurred in the setting of limited resuscitative wishes, or while on MCS were excluded. Patient characteristics and risk factors were analyzed.

RESULTS

Fourteen of 254 (6%) experienced SCA at a median of 3 (1, 4) years post-HT. Seven (50%) events occurred out-of-hospital. Eleven (79%) died from their initial event, 2 (18%) after failure to separate from extracorporeal membrane (ECMO). In univariate analysis, black race, younger donor age, prior acute cellular rejection (ACR) episode, pacemaker and/or ICD in place, and pre-mortem diagnosis of allograft vasculopathy were associated with SCA (P = .003-0.02). In multivariable analysis, history of ACR, younger donor age, and black race retained significance. [OR = 6.3, 95% CI: 1.6-25.4, P = .01], [OR = 0.9, 95% CI: 0.8-1, P = .04], and [OR = 7.3, 95% CI: 1.1-49.9, P = .04], respectively. SCA occurred in 3 patients with a functioning ICD or pacemaker, which failed to restore a perfusing rhythm.

CONCLUSIONS

SCA occurs relatively early after pediatric HT and is usually fatal. Half of events happen at home. Those who received younger donors, have a history of ACR, or are of black race are at increased risk. ICDs/pacemakers may offer limited protection.

Implantable Cardioverter Defibrillators in Patients with Orthotopic Heart Transplant: A Multicenter Case Series

BACKGROUND

Sudden cardiac death (SCD) is common after orthotopic heart transplant (OHT). No clear guidelines for implantable cardioverter defibrillator (ICD) implantation in OHT patients at high risk for SCD currently exist.

OBJECTIVES

To assess the safety, efficacy, and benefit of ICDs and resynchronization therapy post-OHT. We also provide a systematic review of previous reports.

METHODS

A retrospective multicenter cohort study within the United States. Patients with ICD post-OHT between 2000 and 2020 were identified.

RESULTS

We analyzed 16 patients from 4 centers. The mean standard-deviation (SD) age was 43 (18) years at OHT and 51 (20) years at ICD implantation. The mean (SD) duration from OHT to ICD implantation was 9 (5) years. The mean (SD) left ventricular ejection fraction (LVEF) was 35% (17%). There were 2 (13%) post-procedural complications: 1 hematoma and 1 death. Mean (SD) follow-up was 24 (23) months. Survival rate was 63% (10/16) at 1 year and 56% (9/16) at 2 years, with 6/7 of those who died having LVEF < 35% at the time of the ICD implantation. Patients were more likely to receive appropriate therapy if their ICD was implanted for secondary (5/8) rather than primary (0/8) prevention (P = 0.007). Of those who did, 4 patients survived to 30 days post-ICD therapy. Severe CAV was not associated with the rate of appropriate therapy.

CONCLUSIONS

Beneficial outcomes were observed when ICDs were implanted for secondary prevention only, and in patients with higher baseline LVEF. We also observed benefits with resynchronization therapy. This article is protected by copyright. All rights reserved.

Trends, Prevalence, and Outcomes of Sudden Cardiac Arrest Post Cardiac Transplant: A Nationwide 16-Year Study

Heart transplantation is the most effective long-term therapy for end-stage heart disease. There is limited data related to sudden cardiac arrest (SCA) in postheart transplant recipients. We aimed to describe the trends, and rate of SCA following heart transplantation and thereby identify clinical predictors as well as outcomes of SCA in patients post-transplant. We queried the National Inpatient Sample (NIS) with administrative codes for SCA and heart transplant. We assessed baseline differences between SCA and non-SCA admissions, with hazard ratios adjusted for age, gender, CCI, and race. Multivariable logistic regression models were generated to identify the independent predictors for SCA. There was a total of 30,020 hospitalizations of heart transplant recipients between 1999 and 2014 in the United States and among these 1,953 patients (6.5%) suffered SCA with an increasing trend of admissions for SCA. Among the patients who suffered from SCA, 18.83% died during the same hospitalization, 19.29% were discharged to a long-term facility, and 61.38% were discharged home. Multivariate analysis demonstrated that conduction system disorders (Hazard ratio [95% confidence interval]; 7.1 [4.5-11.1]), female gender (HR:1.2 [1.1-1.3]), diabetes (HR:1.4 [1.2-1.6]), and hypertension (HR:1.2 [1.1-1.4]) were the strongest predictors for SCA. SCA hospitalizations occur in 6.5% of patients post cardiac transplant and have been increasing from 1999 to 2014. Conduction block, graft rejection, female gender, hypertension, diabetes are independent predictors for SCA in heart transplant recipients.

Management of Arrhythmias After Heart Transplant: Current State and Considerations for Future Research

Orthotropic heart transplantation remains the most effective therapy for patients with end-stage heart failure, with a median survival of ≈13 years. Yet, a number of complications are observed after orthotropic heart transplantation, including atrial and ventricular arrhythmias. Several factors contribute to arrhythmias, such as autonomic denervation, effect of the surgical technique, acute and chronic rejection, and transplant vasculopathy among others. To minimize risk of future arrhythmias, the bicaval technique and minimizing ischemic time are current surgical standards. Sinus node dysfunction is the most common indication for early (within 30 days) pacemaker implantation, whereas atrioventricular block incidence increases as time from transplant increases. Atrial fibrillation can occur in the first few weeks following transplantation but is uncommon in the long term unless secondary to a precipitant such as acute rejection. The most common atrial arrhythmias are atrial flutters, which are mainly typical, but atypical circuits can be observed such as those that involve the remnant donor atrium in regions immediately adjacent to the atrioatrial anastomosis suture line. Choosing the appropriate pharmacological therapy requires careful consideration due to the potential interaction with immunosuppressive agents. Despite historical concerns, adenosine is effective and safe at reduced doses if administered under cardiac monitoring. Catheter ablation has emerged as an effective treatment strategy for symptomatic supraventricular tachycardias, including ablation of atypical flutter circuits. Cardiac allograft vasculopathy is an important risk factor for sudden cardiac death, yet the role of prophylactic implantable cardioverter-defibrillator implant for sudden death prevention is unclear. Current indications for implantable cardioverter-defibrillator implantation are as in the nontransplant population. A number of questions for future research are posed.

Imaging of Cardiac Transplantation: An Overview

Heart transplantation (HTx) remains the optimal treatment for selected patients with end-stage advanced heart failure. However, survival is limited early by acute rejection and long term by cardiac allograft vasculopathy (CAV). Even though the diagnosis of rejection is based on histology, cardiac imaging provides a pivotal role for early detection and severity assessment of these hazards. The present review focuses on the use and reliability of different invasive and non-invasive imaging modalities to detect and monitor CAV and rejection after HTx. Coronary angiography remains the corner stone in routine CAV surveillance. However, angiograms are invasive and underestimates the CAV severity especially in the early phase. Intravascular ultrasound and optical coherence tomography are invasive methods for intracoronary imaging that detects early CAV lesions not evident by angiograms. Non-invasive imaging can be divided into myocardial perfusion imaging, anatomical/structural imaging and myocardial functional imaging. The different non-invasive imaging modalities all provide clinical and prognostic information and may have a gatekeeper role for invasive monitoring. Acute rejection and CAV are still significant clinical problems after HTx. No imaging modality provides complete information on graft function, coronary anatomy and myocardial perfusion. However, a combination of invasive and non-invasive modalities at different stages following HTx should be considered for optimal personalized surveillance and risk stratification.

Cardiac Implantable Electronic Devices Following Heart Transplantation

Permanent pacemaker (PPM) implantation is required in a subset of patients (∼10%) for sinus node dysfunction or atrioventricular block both early and late after heart transplantation. The incidence of PPM implantation has decreased to <5% with the advent of bicaval anastamosis transplantation surgery. Pacing dependence upon follow-up has been variably reported. An even smaller percentage of transplantation recipients (1.5% to 3.4%) undergo implantable cardioverter-defibrillator (ICD) placement. Rigorous data are lacking for the use of ICDs in the transplantation population and is largely derived from cohort studies and case series. Sudden cardiac death occurs in approximately 10% of transplantation recipients, but multiple nonarrhythmic factors are believed to be responsible, including acute rejection, late graft failure with electromechanical dissociation, and ischemia due to cardiac allograft vasculopathy. This review provides a comprehensive analysis of the existing data regarding the role for PPMs and ICDs in this population, including leadless PPMs and subcutaneous ICDs, special considerations, and future directions.