Myocardial strain assessment using cardiovascular magnetic resonance imaging in recipients of implantable cardioverter defibrillators.

BACKGROUND: Cardiovascular magnetic resonance (CMR) is increasingly used in the evaluation of patients who are potential candidates for implantable cardioverter-defibrillator (ICD) therapy to assess left ventricular (LV) ejection fraction (LVEF), myocardial fibrosis, and etiology of cardiomyopathy. It is unclear whether CMR-derived strain measurements are predictive of appropriate shocks and death among patients who receive an ICD. We evaluated the prognostic value of LV strain parameters on feature-tracking (FT) CMR in patients who underwent subsequent ICD implant for primary or secondary prevention of sudden cardiac death. METHODS: Consecutive patients from 2 Canadian tertiary care hospitals who underwent ICD implant and had a pre-implant CMR scan were included. Using FT-CMR, a single, blinded, reader measured LV global longitudinal (GLS), circumferential (GCS), and radial (GRS) strain. Cox proportional hazards regression was performed to assess the associations between strain measurements and the primary composite endpoint of all-cause death or appropriate ICD shock that was independently ascertained. RESULTS: Of 364 patients (mean 61 years, mean LVEF 32%), 64(17.6%) died and 118(32.4%) reached the primary endpoint over a median follow-up of 62 months. Univariate analyses showed significant associations between GLS, GCS, and GRS and appropriate ICD shocks or death (all p < 0.01). In multivariable Cox models incorporating LVEF, GLS remained an independent predictor of both the primary endpoint (HR 1.05 per 1% higher GLS, 95% CI 1.01-1.09, p = 0.010) and death alone (HR 1.06 per 1% higher GLS, 95% CI 1.02-1.11, p = 0.003). There was no significant interaction between GLS and indication for ICD implant, presence of ischemic heart disease or late gadolinium enhancement (all p > 0.30). CONCLUSIONS: GLS by FT-CMR is an independent predictor of appropriate shocks or mortality in ICD patients, beyond conventional prognosticators including LVEF. Further study is needed to elucidate the role of LV strain analysis to refine risk stratification in routine assessment of ICD treatment benefit.

The Many Care Models to Treat Thoracic Aortic Disease in Canada: A Nationwide Survey of Cardiac Surgeons, Cardiologists, Interventional Radiologists, and Vascular Surgeons.

BACKGROUND: Several specialties treat thoracic aortic disease, resulting in multiple patient care pathways. This study aimed to characterize these varied care models to guide health policy. METHODS: A 57-question e-survey was sent to staff cardiac surgeons, cardiologists, interventional radiologists, and vascular surgeons at 7 Canadian medical societies. RESULTS: For 914 physicians, the response rate was 76% (86 of 113) for cardiac surgeons, 40% (58 of 146) for vascular surgeons, 24% (34 of 140) for radiologists, and 14% (70 of 515) for cardiologists. Several services admitted type B dissections (vascular 37%, cardiology 31%, cardiac 18%, other 7%), and care was heterogeneous. Ownership of disease management was overestimated relative to the perspective of the other specialties. Type A dissection admissions and treatment were more uniform, but emergent call coverage varied. A 24/7 aortic specialist on-call schedule was present only 4% of the time. "Aortic" case rounds promoted attendance by a broader aortic specialty contingency relative to rounds that were specialty specific. Although 89% of respondents felt an aortic team was best for patient care, only 54% worked at an institution with an aortic team present, and only 28% utilized an aortic clinic. Questions designed to define an aortic team derived 63 different combinations. CONCLUSIONS: Thoracic aortic disease follows a network of undefined and variable care pathways, despite its high-risk population in need of complex treatment considerations. Multidisciplinary aortic teams and clinics exist in low volume, and the "aortic team" remains an obscure construct. A multispecialty initiative to define the aortic team and outline standardized navigation pathways within the health systems hospitals is advocated.

CONTEXTE: La prise en charge de la maladie de l'aorte thoracique peut faire appel à plusieurs spécialités, ce qui a pour effet de multiplier les trajectoires de soins des patients. Cette étude visait à caractériser ces différents modèles de soins afin d'éclairer l'élaboration des politiques de santé. MÉTHODOLOGIE: Un sondage électronique de 57 questions a été envoyé aux chirurgiens cardiaques, aux cardiologues, aux radiologistes interventionnels et aux chirurgiens vasculaires membres de 7 associations médicales canadiennes. RÉSULTATS: Sur un total de 914 médecins, le taux de réponse a été de 76 % (86 sur 113) chez les chirurgiens cardiaques, de 40 % (58 sur 146) chez les chirurgiens vasculaires, de 24 % (34 sur 140) chez les radiologistes et de 14 % (70 sur 515) chez les cardiologues. Plusieurs services avaient admis des cas de dissection aortique de type B (chirurgie vasculaire 37 %, cardiologie 31 %, chirurgie cardiaque 18 %, autre 7 %) et les soins étaient hétérogènes. Les spécialistes surestimaient leur responsabilité de la prise en charge des cas par rapport à celle des autres spécialistes. Les admissions de cas de dissection de type A et leur traitement étaient plus uniformes, mais la présence de spécialistes de garde pouvant traiter les cas urgents était variable. La présence continue d'un spécialiste de l'aorte de garde n'était observée que pendant 4 % du temps. Les séances de discussion de cas « aortiques ¼ favorisaient la participation par une gamme plus large de spécialistes de l'aorte que les discussions axées sur une spécialité donnée. Si 89 % des répondants estimaient qu'une équipe « aortique ¼ était la meilleure option pour les soins aux patients, ils n'étaient que 54 % à travailler dans un établissement disposant d'une telle équipe et 28 % à utiliser les services d'une clinique de l'aorte. En réponse aux questions portant sur les éléments constitutifs d'une équipe aortique, 63 combinaisons différentes de spécialités ont été proposées. CONCLUSIONS: La prise en charge de la maladie de l'aorte thoracique emprunte un dédale de trajectoires de soins non définies et variables, alors que sa population à haut risque a besoin de traitements complexes. Les équipes multidisciplinaires et les cliniques spécialisées dans le traitement de l'aorte sont rares, et la notion d' « équipe aortique ¼ demeure un concept obscur. Nous préconisons une initiative réunissant des spécialistes de différents domaines pour définir les éléments constitutifs d'une équipe aortique et établir des trajectoires de navigation normalisées au sein des hôpitaux du système de santé.

Extended-arch repair for acute type-A aortic dissection: perioperative and mid-term results.

OBJECTIVES: Extended-arch techniques offer the potential to comprehensively treat acute type-A aortic dissection (ATAAD), but add surgical complexity compared to the standard hemiarch technique. This study describes both perioperative and mid-term outcomes following the introduction of an extended-arch technique for ATAAD. METHODS: Ours is a retrospective single-centre observational study of 95 consecutive patients with ATAAD from 2011 to 2016. The decision to perform extended-arch or hemiarch repair was individualized based on clinical and radiological features. Extended-arch repair was defined as replacement of the ascending aorta and arch with reimplantation of head vessels with or without distal endovascular extension. Clinical follow-up was 100% complete. Cross-sectional double-oblique measurements were performed for aortic remodelling analysis. RESULTS: Extended-arch (n = 28) and hemiarch (n = 67) repair resulted in a in-hospital mortality of 10% (n = 3) and 10%, (n = 7), and permanent neurological deficit rate of 7% and 12%, respectively. At a mean imaging follow-up duration of 2.7 ± 1.5 years, false lumen thrombosis was achieved in 57% and 9% of patients undergoing extended-arch and hemiarch repair, respectively. Rate of growth in the proximal descending aorta was 0.7 ± 2.3 mm/year in the extended-arch group vs 2.7 ± 3.9 mm/year in the hemiarch group. At a mean clinical follow-up time of 3.0 ± 1.6 years, open surgical aortic reoperation was 0% in the extended-arch group and 22% in the hemiarch group. CONCLUSIONS: Extended-arch repair of ATAAD can be introduced in the acute setting without increase in perioperative mortality or morbidity. At mid-term follow-up, extended-arch for ATAAD improves aortic remodelling and reduces the need for open surgical reoperation.

Hybrid Arch for Acute Type A Aortic Dissection: When to Deploy the Endograft? Debate: Frozen versus Staged?

Advances in open and endovascular techniques have resulted in novel approaches to repair of acute Type A aortic dissection. Hybrid arch procedures involve open arch resection and stent grafting of the descending aorta with stent graft insertion in one of two ways: Frozen or Staged. In this article, pros and cons of the two different paradigms of emerging hybrid arch techniques for acute Type A aortic dissections are discussed.

Cardiac MRI and radionuclide ventriculography for measurement of left ventricular ejection fraction in ICD candidates.

OBJECTIVE: Current guidelines provide left ventricular ejection fraction (LVEF) criterion for use of implantable cardioverter defibrillators (ICD) but do not specify which modality to use for measurement. We compared LVEF measurements by radionuclide ventriculography (RNV) vs cardiac MRI (CMR) in ICD candidates to assess impact on clinical decision making. METHODS: This single-centre study included 124 consecutive patients referred for assessment of ICD implantation who underwent RNV and CMR within 30 days for LVEF measurement. RNV and CMR were interpreted independently by experienced readers. RESULTS: Among 124 patients (age 64 ±â€¯11 years, 77% male), median interval between CMR and RNV was 1 day; mean LVEF was 32 ±â€¯12% by CMR and 33 ±â€¯11% by RNV (p = 0.60). LVEF by CMR and RNV showed good correlation, but Bland-Altman analysis showed relatively wide limits of agreement (-12.1 to 11.4). CMR LVEF reclassified 26 (21%) patients compared to RNV LVEF (kappa = 0.58). LVEF by both modalities showed good interobserver reproducibility (ICC 0.96 and 0.94, respectively) (limits of agreement -7.27 to 5.75 and -8.63 to 6.34, respectively). CONCLUSION: Although LVEF measurements by CMR and RNV show moderate agreement, there is frequent reclassification of patients for ICD placement based on LVEF between these modalities. Future studies should determine if a particular imaging modality for LVEF measurement may enhance ICD decision making and treatment benefit.

Zone 2 Arch Replacement and Staged Thoracic Endovascular Aortic Repair for Acute Type A Aortic Dissection.

Potential benefits of extending the distal extent of repair for acute type A aortic dissection beyond hemiarch has prompted the exploration of various total arch repair approaches. A zone 2 arch is advocated by some surgeons but the nomenclature and technique have not been described.

Complications at the Proximal Landing Zone of Endovascular Stent Grafts Deployed in Surgically Replaced Ascending Aorta.

BACKGROUND: The ascending aorta, with its hostile angulations and forces, is the next frontier in the evolution of endovascular surgery. Type II hybrid arch repair, involving surgical replacement of the ascending aorta, arch debranching, and stent graft deployment in the ascending aortic graft, offers an opportunity to study the behavior of an endovascular prosthesis in the ascending aorta. We report complications seen at the proximal landing zone after type II hybrid arch repair. METHODS: A dedicated imaging protocol was used to monitor 20 consecutive patients who underwent type II hybrid arch repair at a single center from June 2009 to July 2014. RESULTS: Mean age was 66 years (range, 47 to 82 years). Mean imaging follow-up was 34 months (range, 12 to 64 months). There was 1 operative death (5%). Bird beaking (>5 mm of nonapposition) of the stent graft at the proximal landing zone occurred in 12 patients, and >20 mm of bird beaking occurred in 7 patients. Proximal landing zone complications occurred in 4 patients (20%), comprising 2 type Ia endoleaks, 1 graft migration, and 1 graft infolding detected on postoperative days 4, 11, 5, and 755, respectively. Three patients underwent endovascular reintervention for proximal landing zone complications. There were no late deaths. CONCLUSIONS: Thoracic aortic stent grafts may be prone to proximal landing zone complications when deployed in the ascending aorta. Bird beaking is common when endografts are deployed in the Dacron (DuPont, Wilmington, DE) ascending aorta. Angulation issues will likely need to be overcome by stent graft refinement to enable future closed chest approaches to the ascending aorta.