Electrophilic Hydrosilylation of Electron-Rich Alkenes Derived from Enamines.

The low-electron count, air-stable, platinum complexes [Pt(ItBu')(ItBu)][BArF] (C1) (ItBu=1,3-di-tert-butylimidazol-2-ylidene), [Pt(SiPh)3(ItBuiPr)2][BArF] (C2) (ItBuiPr=1-tert-butyl-3-iso-propylimidazol-2-ylidene), [Pt(SiPh)3(ItBuMe)2][BArF] (C3), [Pt(GePh3)(ItBuiPr)2][BArF] (C4), [Pt(GePh)3(ItBuMe)2][BArF] (C5) and [Pt(GeEt)3(ItBuMe)2][BArF] (C6) (ItBuMe=1-tert-butyl-3-methylimidazol-2-ylidene) are efficient catalysts (particularly the germyl derivatives) in both the silylative dehydrocoupling and hydrosilylation of electron rich alkenes derived from enamines. The steric hindrance exerted by the NHC ligand plays an important role in the selectivity of the reaction. Thus, bulky ligands are selective towards the silylative dehydrocoupling process whereas less sterically hindered promote the selective hydrosilylation reaction. The latter is, in addition, regioselective towards the ß-carbon atom of both internal and terminal enamines, leading to ß-aminosilanes. Moreover, the syn stereochemistry of the amino and silyl groups implies an anti Si-H bond addition across the double bond. All these facts point to a mechanistic picture that, according to experimental and computational studies, involves a non-classical hydrosilylation process through an outer-sphere mechanism in which a formal nucleophilic addition of the enamine to the silicon atom of a platinum σ-SiH complex is the key step. This is in sharp contrast with the classical Chalk-Harrod mechanism prevalent in platinum chemistry.

Amiodarone-induced thyrotoxicosis in heart failure with a reduced ejection fraction: A retrospective cohort study.

BACKGROUND: Amiodarone-induced thyrotoxicosis (AIT) is associated with significant morbidity and mortality. We aimed to describe AIT and its clinical outcomes in patients with heart failure with reduced ejection fraction (HFrEF). METHODS: We performed a retrospective chart review at a heart failure center in Winnipeg, Canada. We screened 1059 consecutive patients seen over a 12-month period (August 2011 to July 2012) for AIT in patients with HFrEF. Using descriptive and Cox proportional hazard analyses, we explored the association between AIT and mortality. RESULTS: A total of 110 patients with HFrEF who were exposed to amiodarone were included in the analysis. Of these, 13 (11.8%) were diagnosed with AIT. All AIT patients in our cohort were male. Amiodarone was discontinued in nearly half (46.2%) of patients with AIT. All patients were treated with antithyroid medications, and 5 patients (38.5%) also received prednisone. Euthyroidism was achieved in 2 patients (15.4%), hypothyroidism occurred in 6 patients (46.2%), and 5 patients remained thyrotoxic until death or time of chart review (38.5%). CONCLUSION: Thyrotoxicosis is common in patients with HFrEF on amiodarone and is challenging to treat. Due to the sample size, while no association was found in mortality for patients with HFrEF with AIT, a real association could have been missed.

Peripartum Cardiomyopathy Characteristics and Outcomes in Canadian Aboriginal and Non-Aboriginal Women.

BACKGROUND: Peripartum cardiomyopathy (PPCM) is a heterogeneous condition characterized by heart failure and left ventricular dysfunction (left ventricular ejection fraction [LVEF] < 45%) in the absence of an alternative cause and a previous diagnosis of cardiomyopathy. The Aboriginal population (Inuit, First Nations, Metis) of Canada often has barriers to health care, which can lead to delays in diagnosis and treatment. Our objectives are to describe PPCM in a Canadian population, and to determine if Canadian Aboriginal women have worse clinical outcomes than non-Aboriginal women. METHODS: A retrospective study was performed at a single tertiary care centre, between 2008 and 2014. Demographic characteristics, symptoms at presentation, medical history, discharge medications, blood work, echocardiographic parameters, and follow-up information were collected. RESULTS: A total of 177 women were screened, and 23 were included in the study (52% were Aboriginal). Aboriginal women were found to have higher rates of gravidity and parity, and higher incidence of tobacco smoking than non-Aboriginal women, and were more likely to be discharged with diuretic medications. At diagnosis, Aboriginal women were more likely to have a lower LVEF (20% [interquartile range (IQR), 15%-23%] vs 40% [IQR, 30%-42%]; P = 0.02) and a more dilated left ventricle (left ventricular end-diastolic diameter, 64 mm [IQR, 57-74 mm] vs 54 mm [IQR, 50-57mm]; P < 0.01). Recovery rate, defined as LVEF > 50%, was similar (46% in Aboriginal patients and 60% in non-Aboriginal patients). CONCLUSIONS: Our findings support that Aboriginal women with PPCM are more likely to present with lower LVEF and a more dilated left ventricle, as well, require more symptomatic management. To our knowledge, this is the first description and contrast of PPCM between Aboriginal and non-Aboriginal Canadians.

Anomalous right coronary artery origin in a high school athlete.

Coronary anomalies are the cause of 12% of sudden deaths among athletes. Similarly anomalous coronary origin from the opposite sinus is often found at autopsy. The use of echocardiography to screen for these types of defects may provide a potentially life-saving diagnosis. The authors present a case that highlights the utility of echocardiography as part of a comprehensive screening program for athletes.