Statistiques appliquées en chirurgie cardiaque adulte : analyses de survie et applications du “propensity score”

L'objectif principal de ce travail est d’étudier en profondeur certaines techniques biostatistiques avancées en recherche évaluative en chirurgie cardiaque adulte. Les études ont été conçues pour intégrer les concepts d'analyse de survie, analyse de régression avec “propensity score”, et analyse de coûts. Le premier manuscrit évalue la survie après la réparation chirurgicale de la dissection aigüe de l’aorte ascendante. Les analyses statistiques utilisées comprennent : analyses de survie avec régression paramétrique des phases de risque et d'autres méthodes paramétriques (exponentielle, Weibull), semi-paramétriques (Cox) ou non-paramétriques (Kaplan-Meier) ; survie comparée à une cohorte appariée pour l’âge, le sexe et la race utilisant des tables de statistiques de survie gouvernementales ; modèles de régression avec “bootstrapping” et “multinomial logit model”. L'étude a démontrée que la survie s'est améliorée sur 25 ans en lien avec des changements dans les techniques chirurgicales et d’imagerie diagnostique. Le second manuscrit est axé sur les résultats des pontages coronariens isolés chez des patients ayant des antécédents d'intervention coronarienne percutanée. Les analyses statistiques utilisées comprennent : modèles de régression avec “propensity score” ; algorithme complexe d'appariement (1:3) ; analyses statistiques appropriées pour les groupes appariés (différences standardisées, “generalized estimating equations”, modèle de Cox stratifié). L'étude a démontrée que l’intervention coronarienne percutanée subie 14 jours ou plus avant la chirurgie de pontages coronariens n'est pas associée à des résultats négatifs à court ou long terme. Le troisième manuscrit évalue les conséquences financières et les changements démographiques survenant pour un centre hospitalier universitaire suite à la mise en place d'un programme de chirurgie cardiaque satellite. Les analyses statistiques utilisées comprennent : modèles de régression multivariée “two-way” ANOVA (logistique, linéaire ou ordinale) ; “propensity score” ; analyses de coûts avec modèles paramétriques Log-Normal. Des modèles d’analyse de « survie » ont également été explorés, utilisant les «coûts» au lieu du « temps » comme variable dépendante, et ont menés à des conclusions similaires. L'étude a démontrée que, après la mise en place du programme satellite, moins de patients de faible complexité étaient référés de la région du programme satellite au centre hospitalier universitaire, avec une augmentation de la charge de travail infirmier et des coûts.

Acute aortic dissection with carotid and coronary malperfusion: from imaging to pathology.

Postmortem imaging, including postmortem computed tomography angiography, has become an integral tool in forensic investigation in recent years. A relatively new technique, multiphase postmortem computed tomography angiography, allows detailed visualization of the vascular system and makes it possible to evaluate the dynamic perfusion of aortic branches, including the coronary arteries. Here, we report a case of aortic dissection involving the ascending aorta (type A) with coronary and carotid malperfusion. This case illustrates the complementary use of many of the diagnostic tools that are now available in forensic practice, from imaging to conventional autopsy to pathologic techniques such as immunohistochemistry.

Impact of preoperative central neurologic dysfunction on patients undergoing emergency surgery for type a dissection.

BACKGROUND: Preoperative central neurologic deficits in the context of acute type A dissection are a complex comorbidity and difficult to handle. The aim this study was to analyze this subgroup of patients by comparing them with neurologically asymptomatic patients with type A dissection. Results may help the surgeon in preoperative risk assessment and thereby aid in the decision-making process. METHODS: We reviewed the data of patients admitted for acute type A dissection during the period from 1999 to 2010. Associated risk factors, time to surgery from admission, extension of the dissection, localization of central nervous ischemic lesions, and the influence of perioperative brain protective strategies were analyzed in a comparison of preoperative neurologically deficient to nondeficient patients. RESULTS: Forty-seven (24.5%) of a total of 192 patients had new-onset central neurologic symptoms prior to surgery. Concomitant myocardial infarction (OR 4.9, 95% CI 1.6-15.3, P = 0.006), renal failure (OR 5.9, 95% CI 1.1-32.8, P = 0.04), dissected carotid arteries (OR 9.2, 95% CI 2.4-34.7, P = 0.001), and late admission to surgery at >6 hours after symptom onset (OR 2.7, 95% CI 1.1-6.8, P = 0.04) were observed more frequently in neurologically deficient patients. These patients had a higher 30-day in-hospital mortality on univariate analysis (P = 0.01) and a higher rate of new postoperative neurologic deficits (OR 9.2, 95% CI 2.4-34.7, P = 0.02). Neurologic survivors had an equal hospital stay, and 67% of them had improved symptoms. CONCLUSIONS: The predominance of neurologic symptoms at admission may be responsible for an initial misdiagnosis. The concurrent central nervous system ischemia and myocardial infarction explains a higher mortality rate and a more extensive "character" of the disease. Neurologically deficient patients are at higher risk of developing new postoperative neurologic symptoms, but prognosis for the neurologic evolution of survivors is generally favorable.

Recovery of paraplegia after type B dissection due to spinal collateral recruitment.

Acute paraplegia could be a symptom of aortic dissection due to sudden compromise of arterial spinal cord blood supply. Complete spontaneous neurologic recovery is possible and was observed in the present case 3 hours after symptom onset. Spontaneous spinal cord reperfusion after acute type B dissection was probably due to two main mechanisms. Reperfusion of false lumen and collateral vascular network recruitment, recently confirmed by anatomic animal studies, serve as potential explanations. Favorable evolution of acute paraplegia after aortic dissection exists, but prognosis is uncertain, probably due to individual variable anatomic distribution of spinal cord blood supply.

Intussusception like lesion after fenestration in aortic type B dissection.

We report on a patient with Marfan syndrome who presented a Stanford type B dissection of the descending thoracic aorta in late pregnancy. After a cesarean section, the patient presented a severe obstruction of the mesenteric superior artery. An endovascular fenestration was performed (balloon and guidewire based fenestration). Computed tomography (CT) angiography revealed an intussusception 'like' image of the abdominal aortic layers as a consequence of the fenestration procedure. Because of aneurismal progression in the abdominal aorta, surgical repair of the abdominal aorta and intussusception material removal was achieved six weeks later. The patient is currently in good condition. We conclude that the intussusception could be induced by a guidewire. This fenestration procedure is not recommended in patients with structural aortic disorders.

Dissection of the role of pili and type 2 and 3 secretion systems in adherence and biofilm formation of an atypical enteropathogenic escherichia coli strain

Atypical enteropathogenic Escherichia coli (aEPEC) strains are diarrheal pathogens that lack bundle-forming pilus production but possess the virulence-associated locus of enterocyte effacement. aEPEC strain 1551-2 produces localized adherence (LA) on HeLa cells; however, its isogenic intimin (eae) mutant produces a diffuse-adherence (DA) pattern. In this study, we aimed to identify the DA-associated adhesin of the 1551-2 eae mutant. Electron microscopy of 1551-2 identified rigid rod-like pili composed of an 18-kDa protein, which was identified as the major pilin subunit of type 1 pilus (T1P) by mass spectrometry analysis. Deletion of fimA in 1551-2 affected biofilm formation but had no effect on adherence properties. Analysis of secreted proteins in supernatants of this strain identified a 150-kDa protein corresponding to SslE, a type 2 secreted protein that was recently reported to be involved in biofilm formation of rabbit and human EPEC strains. However, neither adherence nor biofilm formation was affected in a 1551-2 sslE mutant. We then investigated the role of the EspA filament associated with the type 3 secretion system (T3SS) in DA by generating a double eae espA mutant. This strain was no longer adherent, strongly suggesting that the T3SS translocon is the DA adhesin. In agreement with these results, specific anti-EspA antibodies blocked adherence of the 1551-2 eae mutant. Our data support a role for intimin in LA, for the T3SS translocon in DA, and for T1P in biofilm formation, all of which may act in concert to facilitate host intestinal colonization by aEPEC strains. ©2013, American Society for Microbiology.

Computed tomographic coronary angiography in patients with surgically treated type A aortic dissection: preliminary results

Acute type A aortic dissection is a serious emergency with a mortality rate of up to 40% within the first 24 h when left untreated. Surgical therapy needs to be initiated promptly. Due to this urgent situation, preoperative evaluation of the coronary arteries is not routinely performed in these patients. The aim of this study was to evaluate the accuracy of 64-slice computed tomography angiography (CTA) for postoperative coronary artery assessment in these patients. Ten consecutive patients with two or more cardiovascular risk factors were prospectively enrolled. Patients had type A aortic dissection treated surgically with a supracoronary graft of the ascending aorta. Performance of CTA to exclude significant stenosis (>50% lumen narrowing) and/or coronary artery dissection was compared with quantitative coronary angiography. A total of 147 segments were evaluated. Three segments (2%) were excluded from analysis. CTA correctly assessed one of three significant stenoses in three patients and correctly excluded coronary artery disease (CAD) in six of ten patients. One patient was rated false positive. Overall accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT for identifying coronary artery disease by segment was 98%, 33%, 99%, 50%, and 99%, respectively (P<0.05). By patient, it was 70%, 33%, 86%, 50%, and 75%, respectively. No coronary artery dissection was found. Noninvasive CTA may be a viable alternative to conventional angiography for postoperative coronary artery evaluation in patients with surgically treated type A aortic dissection and cardiovascular risk factors. An NPV of 99% should allow for reliable exclusion of CAD. Further studies with higher patient numbers are warranted.

Quality of life after acute type B dissection in the era of thoracic endovascular aortic repair

Conservative management of acute type B aortic dissection is currently being challenged by primary thoracic endovascular aortic repair. Aim was to assess outcome and quality of life after these different approaches using an adjusted standard population as benchmark.

Strategies for subacute/chronic type B aortic dissection: the Investigation Of Stent Grafts in Patients with type B Aortic Dissection (INSTEAD) trial 1-year outcome

Endovascular stent grafting represents a novel concept for type B aortic dissection both in the acute and subacute/chronic setting, with an unknown effect on outcomes.

Midterm results after endovascular treatment of acute, complicated type B aortic dissection

The purpose of this study was to assess the efficacy and midterm results of endovascular treatment of acute, complicated type B aortic dissection.