Faculty Bibliography

Patients with severe aortic stenosis are commonly elderly and with significant comorbidity. Surgical intervention can improve symptoms and survival in severe aortic stenosis. However, a large proportion of patients do not undergo surgical intervention because they are deemed to be inoperable or too high risk. Over the last decade, transcatheter aortic valve replacement (TAVR) has been developed, providing an effective, less-invasive alternative to open cardiac surgery for inoperable or high-risk patients. The purpose of this review is to provide an overview of risk assessment in TAVR. Specifically, this article reviews the epidemiology of aortic stenosis, describes the risks and benefits of TAVR across multiple outcome measures, explores frailty and other elderly risk factors as metrics for improved risk assessment and discusses the application of improved risk assessment in TAVR decisions.

Objectives: Low patency rates of saphenous vein grafts remain a major predicament in surgical revascularization. We examined a novel expandable external support device designed to mitigate causative factors for early and late graft failure. METHODS: For this study, fourteen adult sheep underwent cardiac revascularization using two vein grafts for each; one to the LAD and the other to the obtuse marginal artery. One graft was supported with the device while the other served as a control. Target vessel was alternated between consecutive cases. The animals underwent immediate and late angiography and were then sacrificed for histopathologic evaluation. RESULTS: Of the fourteen animals studied, three died peri-operatively (unrelated to device implanted), and ten survived the follow-up period. Among surviving animals, three grafts were thrombosed and one was occluded, all in the control group (p = 0.043). Quantitative angiographic evaluation revealed no difference between groups in immediate level of graft uniformity, with a coefficient-of-variance (CV%) of 7.39 in control versus 5.07 in the supported grafts, p = 0.082. At 12 weeks, there was a significant non-uniformity in the control grafts versus the supported grafts (CV = 22.12 versus 3.01, p < 0.002). In histopathologic evaluation, mean intimal area of the supported grafts was significantly lower than in the control grafts (11.2 mm^2 versus 23.1 mm^2 p < 0.02). CONCLUSIONS: The expandable SVG external support system was found to be efficacious in reducing SVG's non-uniform dilatation and neointimal formation in an animal model early after CABG. This novel technology may have the potential to improve SVG patency rates after surgical myocardial revascularization.

The Society of Thoracic Surgeons Clinical Practice Guidelines are intended to assist physicians and other health care providers in clinical decision making by describing a range of generally acceptable approaches for the diagnosis, management, or prevention of specific diseases or conditions. These guidelines should not be considered inclusive of all proper methods of care or exclusive of other methods of care reasonably directed at obtaining the same results. Moreover, these guidelines are subject to change over time, without notice. The ultimate judgment regarding the care of a particular patient must be made by the physician in light of the individual circumstances presented by the patient.

Paravalvular leak (PVL) is a frequent complication of transcatheter aortic valve replacement (TAVR) and is seen at a much higher rate after TAVR than after conventional surgical aortic valve replacement. Recent reports indicating that PVL may be correlated with increased late mortality have raised concerns. However, the heterogeneity of methods for assessing and quantifying PVL, and lack of consistency in the timing of such assessments, is a hindrance to understanding its true prevalence, severity, and effect. This literature review is an effort to consolidate current knowledge in this area to better understand the prevalence, progression, and impact of post-TAVR PVL and to help direct future efforts regarding the assessment, prevention, and treatment of this troublesome complication.

BACKGROUND: Paravalvular regurgitation (PVR) is common after transcatheter aortic valve replacement (TAVR) and may be associated with adverse outcomes. Postdilatation (PD) has been proposed to treat PVR without being formally studied. We performed a study to evaluate the safety and efficacy of PD after balloon expandable TAVR. METHODS AND RESULTS: Consecutive cases of TAVR were reviewed for clinical outcomes. Procedural transesophageal echocardiography imaging was reviewed for a subgroup of consecutive patients. PVR areas seen on a short-axis view were measured immediately after deployment, after PD, and at the completion of the study. Stent dimensions measured using angiography and the Paieon's C-THV system pre- and post-PD were compared. Between May 2007 and November 2011, 259 patients underwent TAVR at our institution. PD was performed in 106 patients (41%). These patients had larger annulus, lower cover-index; more often had transfemoral access and implantation of a 26 mm valve. There was a nonsignificant greater rate of cerebrovascular events in PD patients. There was no significant difference in major aortic injury and permanent pacemaker implantation rates between groups. TTE studies were reviewed in 58 patients (35 with PD and 23 without PD). PD patients had larger PVR areas immediately after deployment (40.3+/-17.1 versus 15.4+/-14.2 mm(2); P<0.0001). There was significant reduction in PVR area attributable to PD (21.7+/-9.3 mm(2); P<0.0001). Spontaneous regression of PVR was seen in both groups. PD increased stent dimensions. CONCLUSIONS: This study demonstrates the efficacy of PD at reducing PVR in patients with greater than mild PVR after balloon-expandable TAVR.

Acute kidney injury (AKI) is associated with a poor prognosis after transcatheter aortic valve replacement (TAVR). A paucity of data exists regarding the incidence and effect of AKI after TAVR using the new recommended Valve Academic Research Consortium criteria. At Columbia University Medical Center, 218 TAVR procedures (64.2% transfemoral, 35.8% transapical) were performed from 2008 to July 2011. The creatinine level was evaluated daily until discharge. Using the Valve Academic Research Consortium definitions, the 30-day and 1-year outcomes were compared between patients with significant AKI (AKI stage 2 or 3) and those without significant AKI (AKI stage 0 or 1). Significant AKI occurred in 18 patients (8.3%). Of these 18 patients, 10 (55.6%) had AKI stage 3 and 9 (50%) required dialysis. AKI was associated with a lower baseline mean transvalvular gradient (37.6 +/- 11.4 vs 45.6 +/- 14.8 mm Hg for no AKI, p = 0.03). After TAVR, the AKI group had a greater hemoglobin decrease (3.6 +/- 2.0 vs 2.4 +/- 1.3 g/dl, p = 0.01), greater white blood cell elevation at 72 hours (21.09 +/- 12.99 vs 13.18 +/- 4.82 x 10(3)/mul, p = 0.001), a more severe platelet decrease (118 +/- 40 vs 75 +/- 43 x 10(3)/mul, p <0.0001), and longer hospitalization (10.7 +/- 6.4 vs 7.7 +/- 8.5 days, p <0.001). One stroke (5.6%) occurred in the AKI group compared with 3 (1.5%) in the group without AKI (p = 0.29). The 30-day and 1-year rates of death were significantly greater in the AKI group than in the no-AKI group (44.4% vs 3.0%, hazard ratio 18.1, 95% confidence interval 6.25 to 52.20, p <0.0001; and 55.6% vs 16.0%, hazard ratio 6.32, 95% confidence interval 3.06 to 13.10, p <0.0001, respectively). Periprocedural life-threatening bleeding was the strongest predictor of AKI after TAVR. In conclusion, the occurrence of AKI, as defined by the Valve Academic Research Consortium criteria, is associated with periprocedural complications and a poor prognosis after TAVR.