Management of COVID-19 in a durable left ventricular assist device recipient: A continuity of care perspective.

COVID-19 is impacting the cardiovascular community both here in the United States and globally. The rapidly emerging cardiac complications have heightened implications for those with underlying cardiovascular disease. We describe an early case of COVID-19 in a left ventricular assist device recipient in the United States. We discuss our clinical management during the initial admission, outpatient management, and a unique complication of this disease over a 40-day disease course.

Low thigh muscle mass is associated with coronary artery stenosis among HIV-infected and HIV-uninfected men: The Multicenter AIDS Cohort Study (MACS).

BACKGROUND: HIV-infected individuals are at increased risk for both sarcopenia and cardiovascular disease. Whether an association between low muscle mass and subclinical coronary artery disease (CAD) exists, and if it is modified by HIV serostatus, are unknown. METHODS: We performed cross-sectional analysis of 513 male MACS participants (72% HIV-infected) who underwent mid-thigh computed tomography (CT) and non-contrast cardiac CT for coronary artery calcium (CAC) during 2010-2013. Of these, 379 also underwent coronary CT angiography for non-calcified coronary plaque (NCP) and obstructive coronary stenosis ≥50%. Multivariable-adjusted Poisson regression was used to estimate prevalence risk ratios of associations between low muscle mass (<20th percentile of the HIV-uninfected individuals in the sample) and CAC, NCP and obstructive stenosis. RESULTS: The prevalence of low thigh muscle mass was similar by HIV serostatus (20%). There was no association of low muscle mass with CAC or NCP. However, low thigh muscle mass was significantly associated with a 2.5-fold higher prevalence of obstructive coronary stenosis, after adjustment for demographics and traditional CAD risk factors [PR 2.46 (95% CI 1.51, 4.01)]. This association remained significant after adjustment for adiposity, inflammation, and physical activity. There was no significant interaction by HIV serostatus (p-interaction = 0.90). CONCLUSIONS: In this exploratory analysis, low thigh muscle mass was significantly associated with subclinical obstructive coronary stenosis. Additional studies involving larger sample sizes and prospective analyses are needed to confirm the potential utility of measuring mid-thigh muscle mass for identifying individuals at increased risk for obstructive CAD who might benefit from more aggressive risk factor management.

Frailty and subclinical coronary atherosclerosis: The Multicenter AIDS Cohort Study (MACS).

BACKGROUND AND AIMS: Frailty and cardiovascular disease share many risk factors. We evaluated whether frailty is independently associated with subclinical coronary atherosclerosis and whether any relationships differ by HIV-serostatus. METHODS: We studied 976 [62% HIV-infected] male participants of the Multicenter AIDS Cohort Study who underwent assessment of frailty and non-contrast cardiac CT scanning; of these, 747 men also underwent coronary CT angiography (CCTA). Frailty was defined as having ≥3 of 5 of the following: weakness, slowness, weight loss, exhaustion, and low physical activity. Coronary artery calcium (CAC) was assessed by non-contrast CT, and total plaque score (TPS), mixed plaque score (MPS), and non-calcified plaque score (NCPS) by CCTA. Multivariable-adjusted regression was used to assess the cross-sectional associations between frailty and subclinical coronary atherosclerosis. RESULTS: Mean (SD) age of participants was 54 (7) years; 31% were black. Frailty existed in 7.5% and 14.3% of HIV-uninfected and HIV-infected men, respectively. After adjustment for demographics, frailty was significantly associated with prevalence of any CAC (CAC>0), any plaque (TPS>0), and mixed plaque (MPS>0) in HIV-uninfected but not in HIV-infected men (p-interactionHIV<0.05 for all). Among HIV-uninfected men, after adjustment for cardiovascular risk factors, frailty was significantly associated only with CAC>0 [Prevalence Ratio 1.27 (95%CI 1.02, 1.59)] and TPS>0 [1.19 (1.06, 1.35)]. No association was found for NCPS. CONCLUSIONS: Frailty was independently associated with subclinical coronary atherosclerosis among HIV-uninfected men, but not among HIV-infected men. Further work is needed to ascertain mechanisms underlying these differences and whether interventions that improve frailty (i.e. strength training) can improve cardiovascular outcomes.

Parathyroid Hormone and Subclinical Cerebrovascular Disease: The Atherosclerosis Risk in Communities Brain Magnetic Resonance Imaging Study.

BACKGROUND: Elevated parathyroid hormone (PTH) levels have been associated with cardiovascular disease risk factors and events. We hypothesized that elevated PTH levels would also be associated with subclinical cerebrovascular disease. We examined the relationship between elevated PTH level and white matter hyperintensities (WMHs) and subclinical infarcts measured on brain magnetic resonance imaging (MRI). METHODS: PTH was measured at baseline (1993-1994) among participants free of prior clinical stroke who underwent a brain MRI at baseline (n = 1703) and a second brain MRI 10 years later (n = 948). PTH levels of 65 pg/mL or higher were considered elevated (n = 204). Participants who did not return for a follow-up MRI had, at baseline, higher PTH and a greater prevalence of cardiovascular risk factors (P < .05 for all); therefore, multiple imputation was used. The cross-sectional and prospective associations of PTH levels with WMH and MRI-defined infarcts (and their progression) were investigated using multivariable regression models. RESULTS: At baseline, the participants had a mean age of 62 years and were 60% female and 49% black. Cross-sectionally, after adjusting for demographic and lifestyle factors, elevated PTH level was associated with higher WMH score (ß = .19, 95% confidence interval [CI] .04-.35) and increased odds of prevalent infarcts (odds ratio 1.56, 95% CI 1.02-2.36). Results were attenuated after adjustment for potential mediators of this association (i.e., hypertension). No prospective associations were found between PTH and incident infarcts or change in estimated WMH volume, although estimates were imprecise. CONCLUSIONS: Although associated cross-sectionally, we did not confirm any association between elevated PTH level and progression of cerebrovascular changes on brain MRIs obtained 10 years apart. The relationship of PTH with subclinical brain disease warrants further study.

Crystal structures of Escherichia coli exonuclease I in complex with single-stranded DNA provide insights into the mechanism of processive digestion.

Escherichia coli Exonuclease I (ExoI) digests single-stranded DNA (ssDNA) in the 3'-5' direction in a highly processive manner. The crystal structure of ExoI, determined previously in the absence of DNA, revealed a C-shaped molecule with three domains that form a central positively charged groove. The active site is at the bottom of the groove, while an extended loop, proposed to encircle the DNA, crosses over the groove. Here, we present crystal structures of ExoI in complex with four different ssDNA substrates. The structures all have the ssDNA bound in essentially the predicted manner, with the 3'-end in the active site and the downstream end under the crossover loop. The central nucleotides of the DNA form a prominent bulge that contacts the SH3-like domain, while the nucleotides at the downstream end of the DNA form extensive interactions with an 'anchor' site. Seven of the complexes are similar to one another, but one has the ssDNA bound in a distinct conformation. The highest-resolution structure, determined at 1.95 Å, reveals an Mg(2+) ion bound to the scissile phosphate in a position corresponding to Mg(B) in related two-metal nucleases. The structures provide new insights into the mechanism of processive digestion that will be discussed.