Transcatheter Aortic Valve-in-Valve Replacement for Degenerated Stentless Bioprosthetic Aortic Valves: Results of a Multicenter Retrospective Analysis.

OBJECTIVES: The purpose of this study was to evaluate the safety and efficacy of valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) for stentless bioprosthetic aortic valves (SBAVs) and to identify predictors of adverse events. BACKGROUND: ViV TAVR in SBAVs is associated with unique technical challenges and risks. METHODS: Clinical records and computer tomographic scans were retrospectively reviewed for procedural complications, predictors of coronary obstruction, mortality, and echocardiographic results. RESULTS: Among 66 SBAV patients undergoing ViV TAVR, mortality was 2 of 66 patients (3.0%) at 30 days and 5 of 52 patients (9.6%) at 1 year. At 1 year, left ventricular end-systolic dimension was decreased versus baseline (median [interquartile range (IQR)]: 3.0 [2.6 to 3.6] cm vs. 3.7 [3.2 to 4.4] cm; p < 0.001). Coronary occlusion in 6 of 66 procedures (9.1%) resulted in myocardial infarction in 2 of 66 procedures (3.0%). Predictors of coronary occlusion included subcoronary implant technique compared with full root replacement (6 of 31, 19.4% vs. 0 of 28, 0%; p = 0.01), short simulated radial valve-to-coronary distance (median [IQR]: 3.4 [0.0 to 4.6] mm vs. 4.6 [3.2 to 6.2] mm; p = 0.016), and low coronary height (7.8 [5.8 to 10.0] mm vs. 11.6 [8.7 to 13.9] mm; p = 0.003). Coronary arteries originated <10 mm above the valve leaflets in 34 of 97 unobstructed coronary arteries (35.1%). CONCLUSIONS: TAVR in SBAVs is frequently associated with high-risk coronary anatomy but can be performed with a low risk of death and myocardial infarction, resulting in favorable ventricular remodeling. A subcoronary surgical approach is associated with an increased risk of coronary obstruction.

Conditional targeting: inducible deletion by Cre recombinase.

Tissue specific gene knockouts using Cre recombinase can have broad applicability in murine disease models of cardiovascular disease. The Cre system has been shown to have broad experimental versatility for both temporal and spatial control of gene deletion. By and large this is achieved by first generating mice with an inducible tissue specific promoter for expression of Cre. These mice can then be crossed with a second line of mice where the gene of interest in 'knocked in' flanked by Cre recognition sequences Lox-P sites. The double transgenic lines are then induced, through administration of an exogenous agent, to allow tissue specific, i.e. cardiac, knockout of the gene of interest at the desired time. An experimental protocol delineating this technique is described in the chapter.

Comparison of procedural complications with versus without interventional cardiology fellows-in-training during contemporary percutaneous coronary intervention.

Despite increasing complexity of contemporary procedures at tertiary care hospitals, the relationship between interventional cardiology fellows-in-training (ICFITs) and complications of percutaneous coronary intervention (PCI) has not been reported. We compiled logbooks of 6 ICFITs at an academic hospital and evaluated patient and procedural characteristics of PCIs performed with and without presence of an ICFIT. The primary end point was the composite of all in-hospital PCI complications defined by the American College of Cardiology's National Cardiovascular Data Registry: (1) catheterization laboratory events such as no-reflow and dissection/perforation, (2) general clinical events such as stroke or cardiogenic shock, (3) vascular and bleeding complications, and (4) miscellaneous complications such as peak troponin or creatinine levels. Logistic regression adjusted for differences in measured confounders between patients treated with and without presence of an ICFIT. All analyses were repeated after excluding PCI for ST-elevation myocardial infarction. Of 2,605 PCI procedures at the academic hospital between July 2007 and April 2010, an ICFIT was present for 1,638 procedures (63%). Despite having worse clinical and procedural characteristics, patients in the ICFIT group experienced similar rates of the composite end point (12.9% vs 14.5% without ICFIT, p = 0.27). Longer mean fluoroscopy times and greater number of stents were noted in the ICFIT group; however, hospital length of stay was shorter and no individual adverse events were increased in the ICFIT procedures. Presence of an ICFIT remained unrelated to the composite end point after multivariable adjustment (odds ratio 0.92, 95% confidence interval 0.71 to 1.20; p = 0.53), and findings were similar after excluding PCI for ST-elevation myocardial infarction. In conclusion, in contemporary practice at a large academic medical center, PCI complication rates were not adversely affected by the presence of an ICFIT.