Anas Fares

Comparison of Outcomes of Transfemoral Transcatheter Aortic Valve Implantation Using a Minimally Invasive Versus Conventional Strategy.

Some centers, mostly in Europe, have demonstrated the feasibility of a minimally invasive strategy (MIS; i.e., local anesthesia and conscious sedation, performed in the cath laboratory without transesophageal echocardiography guidance). Nonetheless, the experience of MIS for TAVI using both commercially available valves is lacking in the United States. We, therefore, retrospectively studied all transfemoral TAVI cases performed at our institution between March 2011 and November 2014 to assess the safety and efficacy of MIS. Patients were dichotomized according to the strategy (MIS vs conventional strategy [CS]) used for the procedure. One hundred sixteen patients were included in the MIS group and 91 patients were included in the CS group. Baseline characteristics were similar, and procedural success was comparable (99.1% in MIS and 98.9% in CS, p = 1). One intraprocedural death occurred in each group, whereas conversion rates to general anesthesia were low (3.4%). Comparable device success was obtained. Rates of complications and >mild paravalvular leak before discharge were low and comparable. Length of hospital stay was significantly reduced in the MIS (median, 3.0 [2.0 to 5.0] days) compared with than that in CS group (median 6.0 days [3.5, 8.0]). At a median follow-up of 230 days, no significant difference in survival rate was detected (89% vs 88%, p = 0.9). On average, MIS was associated with remarkable cost saving compared with CS (

Quantitative myocardial perfusion imaging in a porcine ischemia model using a prototype spectral detector CT system.

16,000/case). In conclusion, TAVI through MIS was associated with a shorter postprocedural hospital stay, lower costs, and similar safety profile while keeping procedural efficacy compared with CS.

Failure Mechanisms and Neoatherosclerosis Patterns in Very Late Drug-Eluting and Bare-Metal Stent Thrombosis

We optimized and evaluated dynamic myocardial CT perfusion (CTP) imaging on a prototype spectral detector CT (SDCT) scanner. Simultaneous acquisition of energy sensitive projections on the SDCT system enabled projection-based material decomposition, which typically performs better than image-based decomposition required by some other system designs. In addition to virtual monoenergetic, or keV images, the SDCT provided conventional (kVp) images, allowing us to compare and contrast results. Physical phantom measurements demonstrated linearity of keV images, a requirement for quantitative perfusion. Comparisons of kVp to keV images demonstrated very significant reductions in tell-tale beam hardening (BH) artifacts in both phantom and pig images. In phantom images, consideration of iodine contrast to noise ratio and small residual BH artifacts suggested optimum processing at 70 keV. The processing pipeline for dynamic CTP measurements included 4D image registration, spatio-temporal noise filtering, and model-independent singular value decomposition deconvolution, automatically regularized using the L-curve criterion. In normal pig CTP, 70 keV perfusion estimates were homogeneous throughout the myocardium. At 120 kVp, flow was reduced by more than 20% on the BH-hypo-enhanced myocardium, a range that might falsely indicate actionable ischemia, considering the 0.8 threshold for actionable FFR. With partial occlusion of the left anterior descending (LAD) artery (FFR < 0.8), perfusion defects at 70 keV were correctly identified in the LAD territory. At 120 kVp, BH affected the size and flow in the ischemic area; e.g. with FFR ≈ 0.65, the anterior-to-lateral flow ratio was 0.29 ± 0.01, over-estimating stenosis severity as compared to 0.42 ± 0.01 (p < 0.05) at 70 keV. On the non-ischemic inferior wall (not a LAD territory), the flow ratio was 0.50 ± 0.04 falsely indicating an actionable ischemic condition in a healthy territory. This ratio was 1.00 ± 0.08 at 70 keV. Results suggest that projection-based keV imaging with the SDCT system and proper processing could enable useful myocardial CTP, much improved over conventional CT.

Dynamic myocardial perfusion in a porcine balloon-induced ischemia model using a prototype spectral detector CT

Background—There are few clinical studies on the pathophysiological mechanisms of very late stent thrombosis (VLST). We report optical coherence tomography findings in patients with VLST and compare the findings between bare-metal stents (BMS) and drug-eluting stents (DES). Methods and Results—We conducted a registry of stent thrombosis at 4 North American centers with optical coherence tomography imaging programs SAFE registry (The Study of Late Stent Failure Evaluated by OCT). Images were acquired in 61 patients (42 DES and 19 BMS) presenting with definite VLST. The median duration from implantation to VLST presentation was 51.4 months in the DES and 69.9 months in the BMS group (P=0.011). Uncovered and malapposed struts were observed in 70.5% (43/61) and 62.3% (38/61) of patients, respectively, whereas neoatherosclerosis was revealed in 49.2% (30/61). Stent underexpansion was observed in 42.4% of patients. Malapposed struts and stent underexpansion were more frequently demonstrated in DES than in BMS patients, whereas neoatherosclerosis was frequently observed in BMS (40.5% in DES and 68.4% in BMS; P=0.056). The percentage of frames with neoatherosclerosis was lower in DES than in BMS (15.56% [12.24–28.57] versus, 56.41% [40.74–70.00], respectively; P<0.001). Maximum consecutive lipid neointima length was shorter in DES than in BMS (2.4 [1.2–3.6] and 5.3 [3.0–7.0] mm; P=0.011). Conclusions—Optical coherence tomography imaging demonstrated that VLST in DES and BMS had a wide variety of abnormal findings, such as neoatherosclerosis, uncovered strut, and malapposed strut. Neoatherosclerosis and lipid neointima were more frequently observed and had more longitudinal extension in BMS compared with DES.

Characteristic Features on Morphologic and Topographic Findings of Pulmonary Vein Orifices in Transition From Diastolic Dysfunction to Heart Failure: A Computerized Tomography Study

Myocardial CT perfusion (CTP) imaging is an application that should greatly benefit from spectral CT through the significant reduction of beam hardening (BH) artifacts using mono-energetic (monoE) image reconstructions. We used a prototype spectral detector CT (SDCT) scanner (Philips Healthcare) and developed advanced processing tools (registration, segmentation, and deconvolution-based flow estimation) for quantitative myocardial CTP in a porcine ischemia model with different degrees of coronary occlusion using a balloon catheter. The occlusion severity was adjusted with fractional flow reserve (FFR) measurements. The SDCT scanner is a single source, dual-layer detector system, which allows simultaneous acquisitions of low and high energy projections, hence enabling accurate projection-based material decomposition and effective reduction of BH-artifacts. In addition, the SDCT scanner eliminates partial scan artifacts with fast (0.27s), full gantry rotation acquisitions. We acquired CTP data under different hemodynamic conditions and reconstructed conventional 120kVp images and projection-based monoenergetic (monoE) images for energies ranging from 55keV-to-120keV. We computed and compared myocardial blood flow (MBF) between different reconstructions. With balloon completely deflated (FFR=1), we compared the mean attenuation in a myocardial region of interest before iodine arrival and at peak iodine enhancement in the left ventricle (LV), and we found that monoE images at 70keV effectively minimized the difference in attenuation, due to BH, to less than 1 HU compared to 14 HU with conventional 120kVp images. Flow maps under baseline condition (FFR=1) were more uniform throughout the myocardial wall at 70keV, whereas with 120kVp data about 12% reduction in blood flow was noticed on BH-hypoattenuated areas compared to other myocardial regions. We compared MBF maps at different keVs under an ischemic condition (FFR < 0.7), and we found that flow-contrast-to-noise-ratio (CNRf ) between LAD ischemic and remote healthy territories attains its maximum (2.87 ± 0.7) at 70keV. As energies diverge from 70keV, we noticed a steady decrease in CNRf and an overestimation of mean-MBF. Flow overestimation was also noticed for conventional 120kVp images in different myocardial regions.

Cardiac computed tomography assessment of the near term impact of percutaneous ventricular restoration therapy (parachute(®) ) on mitral valve geometry.

BACKGROUND Diastolic dysfunction (DD), a precursor to clinical heart failure (HF), has traditionally been evaluated by means of echocardiography. Data regarding morphologic descriptions of pulmonary vein (PV) orifices in transition from DD to HF have been lacking. METHODS AND RESULTS We retrospectively studied 124 subjects with computerized tomography (CT)-derived PV parameters and echocardiography-derived diastolic indices. We categorized our subjects as 1) non-DD, 2) DD, or 3) heart failure with preserved ejection fraction (HFpEF) and observed a graded enlargement for 4 PV orifice areas across these groups. Positive linear relationship between the 4 PV orifice areas, echocardiography-derived mean pulmonary capillary wedge pressure (PCWP), and velocity of propagation (VP) were observed. Finally, maximum areas of left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV) significantly increased clinical diagnosis of HFpEF (likelihood-ratio χ(2): from 42.92 to 50.75 and 54.67 for LSPV and LIPV, respectively) when superimposed on left ventricular mass index, PCWP, and left atrial volume. CONCLUSIONS PV size measurements with the use of CT are feasible and further aid in diseases discrimination between preclinical DD and those progressed into HF, even with preserved global pumping. Our data suggest that CT-based PV measures may help to identify subjects at risk for HF.

New insight to estimate under-expansion after stent implantation on bifurcation lesions using optical coherence tomography

The aim of current study is to assess the near term impact of percutaneous ventricular restoration therapy (PVR), Parachute® on mitral valve (MV) geometry by cardiac computed tomography (CCT).

In-hospital outcomes of transcatheter versus surgical aortic valve replacement in end stage renal disease

Optical coherence tomography (OCT) allows full volumetric segmentation of the lumen. However, for the estimation of stent under-expansion we still rely on the conventional method (CM) of single cross-sectional narrowing compared with reference vessel, likely masking true lesion significance, especially for bifurcations and tapered vessels. We, therefore, suggest a novel concept of volumetric metrics that take into account vessel tapering and major side branches and is capable of obtaining ideal lumen area for every frame of the stent by OCT. Forty-four patients with bifurcation lesions were enrolled. In volumetric metrics, expansion index was calculated as [(actual lumen area/ideal lumen area) × 100] in all frames. While minimum expansion index (MEI) was often located in the proximal segment to the major side branch, minimum stent area (MSA) by CM was frequently located in the distal segment (p < 0.001). Furthermore, the frequency of the under-expansion was significantly greater in newly metrics compared with CM [21 (47.7%) and 11 (25.0%), p = 0.045]. New metrics changed the presence of the under-expansion in 40.9% (18/44) of patients and the locations of MEI and MSA were different in 72.7% (32/44) of cases. Volumetric assessment enables to more accurately assess stent under-expansion.

Improvements in Left Ventricular Diastolic Mechanics After Parachute Device Implantation in Patients With Ischemia Heart Failure: A Cardiac Computerized Tomographic Study

Transcatheter aortic valve replacement (TAVR) is an alternative to surgical aortic valve replacement (SAVR) for patients with severe symptomatic aortic stenosis (AS) who are at intermediate and high risk for surgery. Commercial use of TAVR has expanded to patients with end stage renal disease (ESRD).

Evaluating the quality of implantation of percutaneous ventricular restoration device (Parachute®) by cardiac computed tomography

BACKGROUND Percutaneous ventricular restoration therapy with the use of a left ventricle (LV)-partitioning Parachute device has emerged as a clinical treatment option for LV apical aneurysm after extensive anterior myocardial infarction (AMI). We assessed changes of diastolic mechanics and functional improvements following LV Parachute device implantation by means of cardiac computerized tomography (CCT). METHODS AND RESULTS CCT data were obtained from 28 patients before and after LV Parachute device implantation. Diastolic functional indices were determined by means of quantitative CCT assessment: 1) transmitral velocities in early (E) and late (A) diastole and ratio (E/A); 2) early diastolic mitral septal tissue velocity (Ea) and E/Ea; and 3) vortex formation time (VFT). Functional improvements were assessed with the use of New York Heart Association (NYHA) functional classification. Among the study patients, there were no significant differences in all transmitral velocities and E/A, though there was significantly increased Ea, reduced E/Ea, and greater VFT 6 months after LV Parachute device implantation. Finally, the improvement of diastolic functional indices after Parachute treatment correlated with observed clinical functional alterations (Δ E/Ea and Δ NYHA functional class:, r = 0.563; P = .002; Δ VFT and Δ NYHA functional class: r = -0.507; P = .006). CONCLUSIONS LV Parachute device implantation therapy in heart failure caused by AMI and LV apical aneurysm formation showed improvements in several diastolic functional mechanics according to CCT-based measures.