Stephen J. Pettit

How many patients fulfil the surface electrocardiogram criteria for subcutaneous implantable cardioverter-defibrillator implantation?

AIMS To determine the number of patients with a primary or secondary prevention implantable cardioverter-defibrillator (ICD) indication who are eligible for subcutaneous ICD (S-ICD) implantation according to the S-ICD manufacturers surface electrocardiogram (ECG) screening template. METHODS AND RESULTS One hundred and ninety-six ICD patients with a non-paced ventricle were assessed using erect and supine ECG limb lead recordings to simulate the three S-ICD sensing vectors. Each ECG lead was scrutinized by two independent observers. Subcutaneous ICD eligibility required two or more leads to satisfy the S-ICD screening template in both erect and supine positions. Overall, 85.2% of patients [95% confidence interval (CI): 80.2-90.2%] fulfilled surface ECG screening criteria. The proportion of patients with 3, 2, 1, and 0 qualifying leads were 37.2% (95% CI: 30.4-44.0%), 48.0% (95% CI: 41.0-55.0%), 11.2% (95% CI: 6.8-15.6%), and 3.6% (95% CI: 1.0-6.2%). The S-ICD screening template was satisfied more often by Lead III (primary vector, 83.7%, 95% CI: 78.5-88.9%) and Lead II (secondary vector, 82.7%, 95% CI: 77.4-88.0%) compared with Lead I (alternate vector, 52.6%, 95% CI: 45.6-59.6%). A prolonged QRS duration was the only baseline characteristic independently associated with ineligibility for S-ICD implantation. There was 92.9% agreement between the two independent observers in assessment of eligibility using the S-ICD screening template. CONCLUSION About 85.2% of patients with an indication for a primary or secondary prevention ICD have a surface ECG that is suitable for S-ICD implantation when assessed with an S-ICD screening template. There is minor inter-observer variation in assessment of eligibility using the S-ICD screening template.

How Small Is Too Small? A Systematic Review of Center Volume and Outcome After Cardiac Transplantation

Background—The aim of this study was to assess the relationship between the volume of cardiac transplantation procedures performed in a center and the outcome after cardiac transplantation. Methods and Results—PubMed, Embase, and the Cochrane library were searched for articles on the volume–outcome relationship in cardiac transplantation. Ten studies were identified, and all adopted a different approach to data analysis and varied in adjustment for baseline characteristics. The number of patients in each study ranged from 798 to 14401, and observed 1-year mortality ranged from 12.6% to 34%. There was no association between the continuous variables of center volume and observed mortality. There was a weak association between the continuous variables of center volume and adjusted mortality up to 1 year and a stronger association at 5 years. When centers were grouped in volume categories, low-volume centers had the highest adjusted mortality, intermediate-volume centers had lower adjusted mortality, and high-volume centers had the lowest adjusted mortality but were not significantly better than intermediate-volume centers. Category limits were arbitrary and varied between studies. Conclusions—There is a relationship between center volume and mortality in heart transplantation. The existence of a minimum acceptable center volume or threshold is unproven. However, a level of 10 to 12 heart transplants per year corresponds to the upper limit of low-volume categories that may have relatively higher mortality. It is not known whether outcomes for patients treated in low-volume transplant centers would be improved by reorganizing centers to ensure volumes in excess of 10 to 12 heart transplants per year.

Use of implantable cardioverter defibrillators in patients with left ventricular assist devices.

Patients with left ventricular assist devices (LVADs) are at high risk of sustained ventricular arrhythmias, but these may be remarkably well tolerated and the association with sudden death is unclear. Many patients who receive an LVAD already have an implantable cardioverter defibrillator (ICD). While it is standard practice to reactivate a previously implanted ICD in an LVAD recipient, this should include discussion of the revised risks and benefits of ICD therapy following LVAD implantation. In particular, patients should be warned that they might receive a significant number of ICD shocks that may not be life saving. When ICDs are reactivated, device programming should minimize the risk of repeated shocks for non‐sustained or well‐tolerated ventricular arrhythmias. Implantation of a primary prevention ICD after implantation of an LVAD is not supported by current evidence, poses potential risks, and should be the subject of a clinical trial before it becomes standard practice.

ICDs in end-stage heart failure

Implantable cardioverter defibrillators (ICDs) reduce mortality in selected patients with chronic heart failure but prognostic benefit is likely to attenuate with progression to end-stage heart failure. The incidence of multiple futile ICD shocks before death is uncertain. Only individual patients, supported by their healthcare professionals, can decide when ICD therapy becomes futile in end-stage heart failure. Despite consensus that ICD deactivation should be routinely discussed, this rarely occurs in clinical practice for many reasons including uncertainty about when to initiate these discussions and reluctance to confront death and dying. Patient and carer opinions about end-stage heart failure and ICD deactivation may not meet professional expectations. Future research should focus on these opinions and examine interventions that bridge the gap between best practice and the reality of current clinical practice.

Socioeconomic Deprivation and Survival After Heart Transplantation in England

Background—Socioeconomic deprivation (SED) is associated with shorter survival across a range of cardiovascular and noncardiovascular diseases. The association of SED with survival after heart transplantation in England, where there is universal healthcare provision, is unknown. Methods and Results—Long-term follow-up data were obtained for all patients in England who underwent heart transplantation between 1995 and 2014. We used the United Kingdom Index of Multiple Deprivation (UK IMD), a neighborhood level measure of SED, to estimate the relative degree of deprivation for each recipient. Cox proportional hazard models were used to examine the association between SED and overall survival and conditional survival (dependant on survival at 1 year after transplantation) during follow-up. Models were stratified by transplant center and adjusted for donor and recipient age and sex, ethnicity, serum creatinine, diabetes mellitus, and heart failure cause. A total of 2384 patients underwent heart transplantation. There were 1101 deaths during 17 040 patient-year follow-up. Median overall survival was 12.6 years, and conditional survival was 15.6 years. Comparing the most deprived with the least deprived quintile, adjusted hazard ratios for all-cause mortality were 1.27 (1.04–1.55; P=0.021) and 1.59 (1.22–2.09; P=0.001) in the overall and conditional models, respectively. Median overall survival and conditional survival were 3.4 years shorter in the most deprived quintile than in the least deprived. Conclusions—Higher SED is associated with shorter survival in heart transplant recipients in England and should be considered when comparing outcomes between centers. Future research should seek to identify modifiable mediators of this association.

Lamin and the heart

Lamins A and C are intermediate filament nuclear envelope proteins encoded by the LMNA gene. Mutations in LMNA cause autosomal dominant severe heart disease, accounting for 10% of dilated cardiomyopathy (DCM). Characterised by progressive conduction system disease, arrhythmia and systolic impairment, lamin A/C heart disease is more malignant than other common DCMs due to high event rates even when the left ventricular impairment is mild. It has several phenotypic mimics, but overall it is likely to be an under-recognised cause of DCM. In certain clinical scenarios, particularly familial DCM with early conduction disease, the pretest probability of finding an LMNA mutation may be quite high. Recognising lamin A/C heart disease is important because implantable cardioverter defibrillators need to be implanted early. Promising oral drug therapies are within reach thanks to research into the mitogen-activated protein kinase (MAPK) and affiliated pathways. Personalised heart failure therapy may soon become feasible for LMNA, alongside personalised risk stratification, as variant-related differences in phenotype severity and clinical course are being steadily elucidated. Genotyping and family screening are clinically important both to confirm and to exclude LMNA mutations, but it is the three-pronged integration of such genetic information with functional data from in vivo cardiomyocyte mechanics, and pathological data from microscopy of the nuclear envelope, that is properly reshaping our LMNA knowledge base, one variant at a time. This review explains the biology of lamin A/C heart disease (genetics, structure and function of lamins), clinical presentation (diagnostic pointers, electrocardiographic and imaging features), aspects of screening and management, including current uncertainties, and future directions.

Retained pacemaker and implantable cardioverter-defibrillator components after heart transplantation are common and may lead to adverse events

Aims Many patients have a cardiac implantable electronic device (CIED) extracted at the time of heart transplantation. CIED components may be retained after heart transplantation, but their frequency, nature, and clinical significance is uncertain. Methods and results Consecutive patients that underwent heart transplantation over 10 years from 1 January 2007 until 1 January 2017 were identified from the unit database. Pre- and post-operative chest radiographs were reviewed by two independent observers for the presence of CIED components. Adverse events relating to any retained CIED component were recorded. Two hundred and six patients had a CIED removed at the time of transplantation. Retained CIED components were present in 86 (42%) patients. The most common retained CIED components were suture sleeves and superior vena cava (SVC) coils of dual coil implantable cardioverter-defibrillator (ICD) leads. An SVC coil was retained in 25% of patients that had a dual coil ICD lead. Seven adverse events were associated with CIED removal or retained CIED components, including one fatal event. However, retained CIED components were not associated with reduced long-term survival after heart transplantation. Conclusion Retained CIED components were seen in 42% of patients that had a CIED prior to transplantation, may be associated with serious adverse events but are not associated with reduced long-term survival. Cardiac surgeons should be aware of all CIED system components and be familiar with techniques for their complete removal at the time of transplantation.

Deactivation of implantable cardioverter-defibrillators at end of life.

It is inevitable that all patients with implantable cardioverter-defibrillators (ICDs) will die during extended follow-up. End-of-life care planning may become appropriate as a patients condition deteriorates. There is concern about multiple futile shocks in the final hours of life, although the incidence of this problem has been estimated at only 8-16%. Despite broad consensus that ICD deactivation should be discussed as part of end-of-life care planning, the effect of ICD deactivation, in particular whether life expectancy is altered, is uncertain. Many clinicians are reluctant to discuss ICD deactivation. Many patients have misconceptions regarding ICD function and value longevity above quality of life. As such, ICD deactivation is often discussed late or not at all. The management of ICDs in patients approaching death is likely to become a major problem in the coming years. This article will discuss directions in which clinical practice might develop and areas for future research.

Utility of troponin assays for exclusion of acute cellular rejection after heart transplantation: A systematic review

BACKGROUND Acute cellular rejection (ACR) is a common complication in the first year after heart transplantation (HT). Routine surveillance for ACR is undertaken by endomyocardial biopsy (EMB). Measurement of cardiac troponins (cTn) in serum is an established diagnostic test of cardiac myocyte injury. This systematic review aimed to determine whether cTn measurement could be used to diagnose or exclude ACR. METHODS PubMed, Google Scholar and the JHLT archive were searched for studies reporting the result of a cTn assay and a paired surveillance EMB. Significant ACR was defined as International Society for Heart and Lung Transplantataion (ISHLT) Grade ≥3a/≥2R. Considerable heterogeneity between studies precluded quantitative meta-analysis. Individual study sensitivity and specificity data were examined and used to construct a pooled hierarchical summary receiver-operator characteristic (ROC) curve. RESULTS Twelve studies including 993 patients and 3,803 EMBs, of which 3,729 were paired with cTn levels, had adequate data available for inclusion. The overall rate of significant ACR was 12%. There was wide variation in diagnostic performance. cTn assays demonstrated sensitivity of 8% to 100% and specificity of 13% to 88% for detection of ACR. The positive predictive value (PPV) was low but the negative predictive value (NPV) was relatively high (79% to 100%). High-sensitivity cTn assays had greater sensitivity and NPV than conventional cTn assays for detection of ACR (sensitivity: 82% to 100% vs 8% to 77%; NPV: 97% to 100% vs 81% to 95%, respectively). CONCLUSIONS cTn assays do not have sufficient specificity to diagnose ACR in place of EMB. However, hs-cTn assays may have sufficient sensitivity and negative predictive value to exclude ACR and limit the need for surveillance EMB. Further research is required to assess this strategy.

Hepatic portal venous gas complicating Bickerstaff's encephalitis with Guillain Barré overlap

Hepatic portal venous gas (HPVG) is a radiological finding often associated with intestinal ischaemia and high mortality.1 We report a 34-year-old male patient who developed flaccid paralysis of all four limbs, areflexia and ophthalmoplegia after a short viral illness. A diagnosis of Bickerstaffs encephalitis with Guillain Barre overlap was made.2 He was ventilated, treated with immunoglobulins and received enteral nutrition via a nasogastric tube. Some neurological improvement was noted on day 22 in intensive care. On day 23 he developed marked abdominal distention with large volume faeculant nasogastric aspirates. CT …