The major function of vascular smooth muscle cells (SMCs) is contraction to regulate blood pressure and flow. SMC contractile force requires cyclic interactions between SMC alpha-actin (encoded by ACTA2) and the beta-myosin heavy chain (encoded by MYH11). Here we show that missense mutations in ACTA2 are responsible for 14% of inherited ascending thoracic aortic aneurysms and dissections (TAAD). Structural analyses and immunofluorescence of actin filaments in SMCs derived from individuals heterozygous for ACTA2 mutations illustrate that these mutations interfere with actin filament assembly and are predicted to decrease SMC contraction. Aortic tissues from affected individuals showed aortic medial degeneration, focal areas of medial SMC hyperplasia and disarray, and stenotic arteries in the vasa vasorum due to medial SMC proliferation. These data, along with the previously reported MYH11 mutations causing familial TAAD, indicate the importance of SMC contraction in maintaining the structural integrity of the ascending aorta.

clinicaltrials.gov Identifier: NCT02045446.

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BackgroundThe reported incidence of peripartum cardiomyopathy (PPCM) in the United States varies widely. Furthermore, limited information is available on the temporal trends in incidence and outcomes of PPCM.Methods and ResultsWe queried the 2004‐2011 Nationwide Inpatient Sample databases to identify all women aged 15 to 54 years with the diagnosis of PPCM. Temporal trends in incidence (per 10 000 live births), maternal major adverse events (MAE; defined as in‐hospital mortality, cardiac arrest, heart transplant, mechanical circulatory support, acute pulmonary edema, thromboembolism, or implantable cardioverter defibrillator/permanent pacemaker implantation), cardiogenic shock, and mean length of stay were analyzed. From 2004 to 2011, we identified 34 219 women aged 15 to 54 years with PPCM. The overall PPCM rate was 10.3 per 10 000 (or 1 in 968) live births. PPCM incidence increased from 8.5 to 11.8 per 10 000 live births (Ptrend<0.001) over the past 8 years. MAE occurred in 13.5% of patients. There was no temporal change in MAE rate, except a small increase in in‐hospital mortality and mechanical circulatory support (Ptrend<0.05). Cardiogenic shock increased from 1.0% in 2004 to 4.0% in 2011 (Ptrend<0.001). Mean length of stay decreased during the study period.ConclusionFrom 2004 to 2011, the incidence of PPCM has increased in the United States. Maternal MAE rates overall have remained unchanged while cardiogenic shock, utilization of mechanical circulatory support, and in‐hospital mortality have increased during the study period. Further study of the mechanisms underlying these adverse trends in the incidence and outcomes of PPCM are warranted.

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