Nandan S. Anavekar

Bicuspid Aortic Valve Identifying Knowledge Gaps and Rising to the Challenge From the International Bicuspid Aortic Valve Consortium (BAVCon)

> Everything should be kept as simple as possible, but no simpler. > > —Albert Einstein1 Since its estimated first description >500 years ago by Leonardo da Vinci,2 the bicuspid aortic valve (BAV) has progressively built a reputation; initially, as a curious valvular phenotype with a tendency to develop obstruction and insufficiency. In more contemporary times, however, the BAV is recognized as underlying almost 50% of isolated severe aortic stenosis cases requiring surgery,3 and has been extensively associated with ominous outcomes such as bacterial endocarditis and aortic dissection.4 These associations, coupled with the high prevalence of BAV in humans,5 have prompted investigative efforts into the condition, which although insightful, have generated more questions than answers. This review describes our current knowledge of BAV, but, more importantly, it highlights knowledge gaps and areas where basic and clinical research is warranted. Our review has 2 sections. The first section outlines the multifaceted challenge of BAV, our current understanding of the condition, and barriers that may hamper the advancement of the science. The second section proposes a roadmap to discovery based on current imaging, molecular biology, and genetic tools, recognizing their advantages and limitations. ### A Condition Characterized by Variable Clinical Presentation The clinical presentation and consequences of BAV in humans are exceedingly heterogeneous, with few clinical or molecular markers to predict associated complications.4,6 BAV can be diagnosed at any stage during a lifetime, from newborns7 to the elderly,8 and in the setting of variable clinical circumstances. Some are benign circumstances such as auscultatory abnormalities or incidental echocardiographic findings in otherwise healthy patients8; other circumstances are morbid, such as early severe aortic valve dysfunction, premature congestive heart failure, and thoracic aortic aneurysms (TAAs).8,9 Life-threatening circumstances include bacterial endocarditis and acute aortic dissection.8–11 These complications may present …

The Impact of Valve Surgery on 6-Month Mortality in Left-Sided Infective Endocarditis

Background— The role of valve surgery in left-sided infective endocarditis has not been evaluated in randomized controlled trials. We examined the association between valve surgery and all-cause 6-month mortality among patients with left-sided infective endocarditis. Methods and Results— A total of 546 consecutive patients with left-sided infective endocarditis were included. To minimize selection bias, propensity score to undergo valve surgery was used to match patients in the surgical and nonsurgical groups. To adjust for survivor bias, we matched the follow-up time so that each patient in the nonsurgical group survived at least as long as the time to surgery in the respective surgically-treated patient. We also used valve surgery as a time-dependent covariate in different Cox models. A total of 129 (23.6%) patients underwent surgery within 30 days of diagnosis. Death occurred in 99 of the 417 patients (23.7%) in the nonsurgical group versus 35 deaths among the 129 patients (27.1%) in the surgical group. Eighteen of 35 (51%) patients in the surgical group died within 7 days of valve surgery. In the subset of 186 cases (93 pairs of surgical versus nonsurgical cases) matched on the logit of their propensity score, diagnosis decade, and follow-up time, no significant association existed between surgery and mortality (adjusted hazard ratio, 1.3; 95% confidence interval, 0.5 to 3.1). With a Cox model that incorporated surgery as a time-dependent covariate, valve surgery was associated with an increase in the 6-month mortality with an adjusted hazard ratio of 1.9 (95% confidence interval, 1.1 to 3.2). Because the proportionality hazard assumption was violated in the time-dependent analysis, we performed a partitioning analysis. After adjustment for early (operative) mortality, surgery was not associated with a survival benefit (adjusted hazard ratio, 0.92; 95% confidence interval, 0.48 to 1.76). Conclusions— The results of our study suggest that valve surgery in left-sided infective endocarditis is not associated with a survival benefit and could be associated with increased 6-month mortality, even after adjustment for selection and survivor biases as well as confounders. Given the disparity between the results of our study and those of other observational studies, well-designed prospective studies are needed to further evaluate the role of valve surgery in endocarditis management.

Epidemiological trends of infective endocarditis: a population-based study in Olmsted County, Minnesota.

OBJECTIVE To provide a contemporary profile of epidemiological trends of infective endocarditis (IE) in Olmsted County, Minnesota. PATIENTS AND METHODS This study consists of all definite or possible IE cases among adults in Olmsted County from January 1, 1970, through December 31, 2006. Cases were identified using resources of the Rochester Epidemiology Project. RESULTS We identified 150 cases of IE. The age- and sex-adjusted incidences of IE ranged from 5.0 to 7.9 cases per 100,000 person-years with an increasing trend over time differential with respect to sex (for interaction, P=.02); the age-adjusted incidence of IE increased significantly in women (P=.006) but not in men (P=.79). We observed an increasing temporal trend in the mean age at diagnosis (P=.04) and a decreasing trend in the proportion of cases with rheumatic heart disease as a predisposing condition (P=.02). There were no statistically significant temporal trends in the incidence of either Staphylococcus aureus or viridans group streptococcal IE. Data on infection site of acquisition were available for cases seen in 2001 and thereafter, with 50.0% designated as health care-associated, 42.5% community-acquired, and 7.5% nosocomial. CONCLUSION The incidence of IE among women increased from 1970 to 2006. Ongoing surveillance is warranted to determine whether the incidence change in women will be sustained. Subsequent analysis of infection site of acquisition and its impact on the epidemiology of IE are planned.

Incidence of Infective Endocarditis Caused by Viridans Group Streptococci Before and After Publication of the 2007 American Heart Association's Endocarditis Prevention Guidelines

Background— The American Heart Association published updated guidelines for infective endocarditis (IE) prevention in 2007 that markedly restricted the use of antibiotic prophylaxis in certain at-risk patients undergoing dental and other invasive procedures. The incidence of IE caused by viridans group streptococci (VGS) in the United States after publication of the 2007 American Heart Association guidelines has not been reported. Methods and Results— We performed a population-based review of all definite or possible cases of VGS-IE using the Rochester Epidemiology Project of Olmsted County, Minnesota. Patient demographics and microbiological data were collected for all VGS-IE cases diagnosed from January 1, 1999, through December 31, 2010. We also examined the Nationwide Inpatient Sample hospital discharge database to determine the number of VGS-IE cases included between 1999 and 2009. We identified 22 cases with VGS-IE in Olmsted County over the 12-year study period. Rates of incidence (per 100 000 person-years) during time intervals of 1999–2002, 2003–2006, and 2007–2010 were 3.19 (95% confidence interval, 1.20–5.17), 2.48 (95% confidence interval, 0.85–4.10), and 0.77 (95% confidence interval, 0.00–1.64), respectively (P=0.061 from Poisson regression). The number of hospital discharges with a VGS-IE diagnosis in the Nationwide Inpatient Sample database during 1999–2002, 2003–2006, and 2007–2009 ranged between 15 318 to 15 938, 16 214 to 17 433, and 14 728 to 15 479, respectively. Conclusions— On the basis of data complete through 2010, there has been no perceivable increase in the incidence of VGS-IE in Olmsted County, Minnesota, since the publication of the 2007 American Heart Association endocarditis prevention guidelines.

Magnetic resonance elastography as a method to estimate myocardial contractility

To determine whether increasing epinephrine infusion in an in vivo pig model is associated with an increase in end‐systolic magnetic resonance elastography (MRE)‐derived effective stiffness.

Pericardiectomy vs Medical Management in Patients With Relapsing Pericarditis

OBJECTIVE To determine whether surgical pericardiectomy is a safe and effective alternative to medical management for chronic relapsing pericarditis. PATIENTS AND METHODS Retrospective review of 184 patients presenting to the Mayo Clinic in Rochester, Minnesota, from January 1, 1994, through December 31, 2005, with persistent relapsing pericarditis identified 58 patients who had a pericardiectomy after failed medical management and 126 patients who continued with medical treatment only. The primary outcome variables were in-hospital postoperative mortality or major morbidity, all-cause death, time to relapse, and medication use. RESULTS Mean ± SD follow-up was 5.5 ± 3.5 years in the surgical group and 5.4 ± 4.4 years in the medical treatment group. At baseline, patients in the surgical group had higher mean relapses (6.9 vs 5.5; P=.01), were more likely to be taking colchicine (43.1% [n=25] vs 18.3% [n=23]; P=.002) and corticosteroids (70.7% [n=41] vs 42.1% [n=53]; P<.001), and were more likely to have undergone a prior pericardiotomy (27.6% [n=16] vs 11.1% [n=14]; P=.003) than the medical treatment group. Perioperative mortality (0%) and major morbidity (3%; n=2) were minimal. Kaplan-Meier analysis revealed no differences in all-cause death at follow-up (P=.26); however, the surgical group had a markedly decreased relapse rate compared with the medical treatment group (P=.009). Medication use was notably reduced after pericardiectomy. CONCLUSION In patients with chronic relapsing pericarditis in whom medical management has failed, surgical pericardiectomy is a safe and effective method of relieving symptoms.

CT and MR Imaging of the Mitral Valve: Radiologic-Pathologic Correlation

Computed tomography (CT) and magnetic resonance (MR) imaging are increasingly important adjuncts to echocardiography for the evaluation of mitral valve disease. The mitral valve may be involved in various acquired or congenital conditions with resultant regurgitation or stenosis, and many of these conditions can be identified with CT or MR imaging. In addition, CT is useful for detecting and monitoring postoperative complications after mitral valve repair or replacement. As the use of CT and MR imaging increases, awareness of the CT and MR imaging appearances of the normal mitral valve and the various disease processes that affect it may foster recognition of unsuspected mitral disease in patients undergoing imaging for other purposes. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.306105518/-/DC1.

Incidence of Infective Endocarditis Due to Viridans Group Streptococci Before and After the 2007 American Heart Association's Prevention Guidelines: An Extended Evaluation of the Olmsted County, Minnesota, Population and Nationwide Inpatient Sample.

OBJECTIVE To determine whether the incidence of infective endocarditis (IE) due to viridans group streptococci (VGS) increased after the publication of the 2007 American Heart Association (AHA) IE prevention guidelines. PATIENTS AND METHODS We performed a population-based survey of all adults (18 years and older) residing in Olmsted County, Minnesota, from January 1, 1999, through December 31, 2013, to identify definite or possible cases of VGS-IE using the Rochester Epidemiology Project. The National (Nationwide) Inpatient Sample hospital discharge database was examined to determine the number of VGS-IE cases in the United States between 2000 and 2011. RESULTS Rates of incidence (per 100,000 person-years) during the intervals of 1999-2002, 2003-2006, 2007-2010, and 2011-2013 were 3.6 (95% CI, 1.3-5.9), 2.7 (95% CI, 0.9-4.4), 0.7 (95% CI, 0.0-1.6), and 1.5 (95% CI, 0.2-2.9), respectively, reflecting an overall significant decrease (P=.03 from Poisson regression). Likewise, nationwide estimates of hospital discharges with a VGS-IE diagnosis trended downward during 2000-2011, with a mean number per year of 15,853 and 16,157 for 2000-2003 and 2004-2007, respectively, decreasing to 14,231 in 2008-2011 (P=.05 from linear regression using weighted least squares method). CONCLUSION Despite major reductions in the number of indications for antibiotic prophylaxis for invasive dental procedures espoused by the 2007 AHA IE prevention guidelines, both local and national data indicate that the incidence of VGS-IE has not increased.

Hepatic and Splenic Stiffness Augmentation Assessed with MR Elastography in an in vivo Porcine Portal Hypertension Model

To investigate the influence of portal pressure on the shear stiffness of the liver and spleen in a well‐controlled in vivo porcine model with magnetic resonance elastography (MRE). A significant correlation between portal pressure and tissue stiffness could be used to noninvasively assess increased portal venous pressure (portal hypertension), which is a frequent clinical condition caused by cirrhosis of the liver and is responsible for the development of many lethal complications.

In vivo assessment of MR elastography-derived effective end-diastolic myocardial stiffness under different loading conditions.

To compare magnetic resonance elastography (MRE) effective stiffness to end‐diastolic pressure at different loading conditions to demonstrate a relationship between myocardial MRE effective stiffness and end‐diastolic left ventricular (LV) pressure.