https://orcid.org/0009-0001-9438-4652
Abstract
Tricuspid regurgitation (TR) is a common valvular complication following heart transplantation. Transcatheter tricuspid valve replacement exists as a novel treatment option. However, as with any procedure, important complications can occur and warrant discussion.
A 46-year-old woman, status post-orthotopic heart transplant (HT), developed symptomatic severe TR. She underwent transcatheter tricuspid valve replacement (TTVR; EVOQUE system, Edwards Lifesciences) and was subsequently presented to the hospital following a syncopal event. She was found to be in cardiogenic shock with complete heart block on an electrocardiogram that degenerated into sudden cardiac death. Although the valve was well-seated, autopsy revealed areas of focal necrosis where the bioprosthetic valve was seated in the region of the atrioventricular node and His bundle.
This is the first case report of a complication of transcatheter tricuspid valve replacement in a heart transplant patient resulting in complete heart block and sudden cardiac death. While TTVR may be a good treatment option for select patients in this high-risk group, conduction system damage is a potential complication given the anatomy of the region and requires very close monitoring. This case further highlights the unique physiology of HT patients and illustrates the fact that bradyarrhythmias are often poorly tolerated and potentially lethal.
To highlight that tricuspid regurgitation is a common complication following heart transplantation and transcatheter valve replacement is a potential novel treatment option.
To identify atrioventricular conduction blocks as a potential complication following transcatheter tricuspid valve replacement.
To recognize that bradyarrhythmias are often poorly tolerated in the heart transplant patient given their unique physiology.
Introduction
Heart transplantation (HT) has significantly improved the outcomes for patients with advanced heart failure. Tricuspid regurgitation (TR) is a common complication following HT with reported incidences ranging from 20% to 84%.1,2 Though the aetiology of TR following HT can vary, it is frequently associated with repeated endomyocardial biopsies and chordal damage.1,2 Those with moderate to severe TR often develop evidence of right heart failure associated with increased morbidity and mortality.1–5 Due to the risks of traditional surgical approaches in this population, this has led to the consideration of percutaneous techniques to repair or replace the tricuspid valve. Here, we present a case of complete heart block and subsequent sudden cardiac death in an HT patient following transcatheter tricuspid valve replacement (TTVR).
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Case presentation
A 46-year-old woman was brought by ambulance to a community hospital emergency department (ED) following a syncopal episode. Her cardiac history was significant for prior post-partum cardiomyopathy, status post-orthotopic HT 7 years prior. Her post-operative course was complicated by antibody-mediated rejection, cardiac allograft vasculopathy affecting multiple vessels treated with percutaneous coronary intervention, and chronic resistant and recurrent cytomegalovirus infection. She went on to develop end-stage kidney disease requiring haemodialysis and eventually renal transplantation, which failed. She was followed routinely in the HT clinic at a tertiary referral hospital, but on this occasion, she was presented to a community hospital ED.
One year prior to this presentation, she developed dyspnoea, worsening peripheral oedema, and ascites without evidence of cirrhosis requiring routine paracentesis and increased dialysis frequency (five times a week). An echo was notable for mildly reduced left ventricular systolic function (ejection fraction, 45%), a moderately dilated right ventricle with mildly reduced systolic function, severe TR secondary to malcoaptation without evidence of leaflet or chordal damage, a right ventricular systolic pressure of 30–35 mmHg, and a tricuspid annulus measuring 50 mm. A right heart catheterization demonstrated a right atrial pressure of 28 mmHg, right ventricular pressures of 46/24 mmHg, mean pulmonary artery pressure of 36 mmHg, pulmonary capillary wedge pressure of 28 mmHg, cardiac output of 3.6 L/min by the Fick method, and a pulmonary vascular resistance of 2.2 Wood units. Due to significant comorbidities, high surgical risk, and symptoms refractory to medical management, a minimally invasive TriClip repair was initially considered. However, the decision was made to instead pursue TTVR with the EVOQUE system (Edwards Lifesciences).
Six days prior to her ED visit, she underwent an uncomplicated transfemoral TTVR. A post-procedure echo demonstrated a well-seated bioprosthetic valve with a mean gradient of 4 mmHg and trace intravalvular regurgitation without paravalvular regurgitation. A pre-discharge electrocardiogram (ECG) demonstrated normal sinus rhythm (Figure 1, top). She was discharged post-operative day 3 with an ambulatory 14-day ECG monitor as per local policy and a prescription for apixaban 2.5 mg twice daily. She was not on any beta-blockers, calcium channel blockers, or other antiarrhythmic medications.
Top: electrocardiogram prior to hospital discharge following transcatheter tricuspid valve replacement. Middle: electrocardiogram in the emergency department demonstrating complete heart block. Bottom: ambulatory electrocardiogram monitoring demonstrating complete heart block detected 1 day prior to emergency department visit.
Post-procedure day 6, she was brought by ambulance to a community hospital ED following a syncopal episode. Ambulance ECGs demonstrated intermittent complete heart block with heart rate in the 30 s. In the ED, ECGs again demonstrated intermittent complete heart block with heart rate in the 30 s (Figure 1, middle). She was hypotensive with a systolic blood pressure of 60–70 mmHg and hypoxic requiring supplemental oxygen. She was started on isoproterenol (4 μg/min) and norepinephrine (10 μg/min) infusions. Initial bloodwork was notable for metabolic acidosis with a venous pH of 7.18 (normal, 7.30–7.40), an elevated serum lactate of 6.9 mmol/L (normal, 0.5–2.2 mmol/L), and a serum potassium of 4.2 mmol/L (normal, 3.5–5.0 mmol/L). Unfortunately, despite resuscitative efforts in the ED, she rapidly decompensated before a percutaneous temporary pacing wire could be placed and ultimately passed away.
Autopsy revealed a normally seated bioprosthetic valve without evidence of perforation, abscess, or thrombus/vegetation (Figure 2). However, there was focal necrosis where the valve was seated just inferior to the atrioventricular node and His bundle seen on microscopy (Figure 3). The prior coronary stents were patent without signs of acute myocardial infarction, and there was no evidence of allograft rejection, aortic dissection, or pulmonary embolism. The post-discharge 14-day ambulatory ECG monitor revealed she had developed intermittent complete heart block the day prior to her ED visit (Figure 1, bottom).
Dissection of the right ventricle demonstrating the bioprosthetic tricuspid valve in position.
Left: longitudinal haematoxylin and eosin stained section including the right atrium (RA), the crest of the ventricular septum (V), atrioventricular node (small arrow), tricuspid valve (large arrow), and zone of necrosis (large box) where valve anchor post abutted the ventricle wall. Right: higher magnification (of left small box) showing zone of coagulation necrosis with acute neutrophilic inflammatory response.
Discussion
TR is a common complication post HT and has been associated with developing right heart failure, peripheral oedema, and congestive hepatopathy resulting in increased morbidity and mortality.1–5 The aetiologies of TR following HT are multifactorial and linked to valve anatomy and HT complications.6 The tricuspid valve is composed of three leaflets (anterior, posterior, septal) supported by the fibrous tricuspid annulus and attached to the papillary muscles of the right ventricle via chordae tendineae. The annulus is a dynamic structure that can alter depending on loading pressures, heart rate, and contractility. Thus, examples of how TR can develop post HT include surgical annulus distortion resulting in leaflet malcoaptation, right ventricular dysfunction from allograft rejection, or ruptured chordae tendineae from endomyocardial biopsies used to detect rejection. Our patient had several of these factors that likely contributed to the development of TR post HT.
Historically, diuretics to reduce congestion have been the primary management option post HT. However, procedural intervention may be required in patients refractory to medical management. Surgical valve repair is an option but has been associated with increased perioperative risk.7 This has led to increased interest in percutaneous techniques such as TTVR.8 However, there are several complications to consider related to the placement of the valve in relation to anatomical structures. Notably, the anchoring of the valve in the septal tricuspid annulus near the atrioventricular node and His bundle poses the risk of potential damage and subsequent atrioventricular conduction blocks. The TRISCEND trial9 studied transfemoral TTVR in non-HT patients with severe symptomatic TR and found a 1.7% 30-day cardiovascular mortality rate. Importantly, the need for a new permanent pacemaker occurred in 13.3% of patients, all of which were within 9 days post-procedure.9 Currently, there is significant practice variation following TTVR in HT and non-transplant patients. However, data extrapolated from transcatheter aortic valve replacements (which similarly can damage the conduction system) suggest that routine post-procedure ambulatory ECG monitoring can help in detecting conduction abnormalities.10 Importantly, prior research has shown that using real-time cardiac rhythm monitoring technology and notifications to healthcare teams allowed for rapid identification of conduction abnormalities following transcatheter aortic valve replacement.11 Employing real-time monitoring technology and protocols to alert healthcare providers rapidly could potentially reduce major adverse events.
Lastly, and most importantly, this case highlights cardiac physiology that is unique to the HT patient. During transplantation, the donor heart undergoes complete parasympathetic and sympathetic denervation, with reinnervation that can occur to varying degrees post-transplantation.12 Overall, parasympathetic denervation has a larger impact with HT patients often having higher resting heart rates, reduced heart rate variability, and significant chronotropic incompetence when compared to non-transplant controls.12,13 While beta-blockers are essential in managing heart failure in non-transplant patients, they are usually avoided in HT patients for concern of reducing cardiac output and functional capacity.14 Thus, while complete heart block may be relatively well tolerated in non-HT patients, it can potentially lead to cardiogenic shock and/or sudden cardiac death in HT patients, as in this case. Regardless of HT status, contemporary guidelines provide a Class I recommendation for urgent cardiac pacing in complete heart block.15 Prompt recognition of complete heart block and initiation of pacing potentially could have altered the clinical course of this case.
Conclusion
Given the high incidence and progressive nature of TR post HT, TTVR is potentially a good treatment option for select patients in this high-risk group. In this case, the valve procedure was successful with adequate placement and function, but conduction system damage occurred as a complication resulting in death. The case highlights the unique physiology of HT patients and illustrates that bradyarrhythmias are often poorly tolerated and potentially lethal. As such, very close monitoring and enhanced physician awareness/education in the first 2 weeks post-procedure should strongly be considered.
Lead author biography
Dr. Andy Jiang completed medical school at the University of British Columbia, Vancouver BC, Canada, and subsequently completed his residency in Internal Medicine at the University of Western Ontario, London, ON, Canada. He is now a cardiology fellow at the Libin Cardiovascular Institute at the University of Calgary, AB, Canada with a broad interest in various areas of cardiology.
Acknowledgements
None.
Consent: The authors confirm that informed consent for this publication was provided by the next of kin in accordance with Committee on Publication Ethics (COPE) best practice guidelines.
Funding: None declared.
Data availability
The data underlying this article will be shared on reasonable request to the corresponding author.
References
Author notes
Conflict of interest: None declared.
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