Shivak Sharma

EVALUATION OF GI BLEEDING AFTER IMPLANTATION OF LEFT VENTRICULAR ASSIST DEVICE

BACKGROUND Left ventricular assist devices (LVADs) have revolutionized the management of end-stage heart failure (ESHF). However, unexpectedly high rates of GI bleeding (GIB) have been described, and etiology and outcome remain unclear. OBJECTIVE To determine the prevalence, etiology, and outcome of GIB in LVAD recipients. DESIGN Retrospective case series. SETTING Tertiary care academic university hospital. PATIENTS 154 ESHF patients (55.4 years, 122 men/32 women) with LVADs implanted over a 10-year period. MAIN OUTCOME MEASUREMENTS Overt or occult GIB prompting endoscopic evaluation ≥ 7 days after LVAD implantation. RESULTS Over a mean of 0.9 ± 0.1 years of follow-up, 29 patients (19%) experienced 44 GIB episodes. Patients with GIB were older and received anticoagulation therapy before devices were implanted (P ≤ .02 for each). GIB was overt (n = 31) rather than occult (n = 13), and most patients presented with melena (n = 22, 50%); hemodynamic instability was observed in 13.6%. Each bleeding episode required 2.1 ± 0.1 diagnostic or therapeutic procedures, and a source was localized in 71%. Upper endoscopy provided the highest diagnostic yield; peptic bleeding (n = 14) and vascular malformations (n = 8) dominated the findings. Endoscopy was safe and well tolerated. Overall mortality was 35%, none directly from GIB. LIMITATION Retrospective design. CONCLUSIONS Rates of GIB with LVADs are higher than that seen in other patient populations, including those receiving anticoagulation and antiplatelet therapy. GIB episodes are mostly overt and predominantly from the upper GI tract. Endoscopy is safe in the LVAD population.

Anemia: An independent predictor of death and hospitalizations among elderly patients with atrial fibrillation

BACKGROUND Anemia and atrial fibrillation (AF) are common among the elderly. Anemia is an independent predictor of mortality and morbidity for numerous cardiovascular and noncardiovascular diseases, but the association of anemia with mortality and hospitalizations in patients with AF requires clarification. METHODS Subjects were 13,067 Medicare beneficiaries hospitalized with AF and included in the National Registry of Atrial Fibrillation II data set. Index hospitalization hematocrit (Hct) was obtained by structured chart abstraction. Cox proportional hazards models quantified the association of Hct with mortality and re-hospitalizations during a median follow-up period of 12 months. RESULTS The mean age was 79.8 years, 58% were women, and the mean Hct was 39.2%. Hematocrit was significantly (P < .0001) associated with risk of death and of rehospitalization even after adjustment for demographic information, comorbid conditions, and use of cardiovascular medications. As compared to a Hct of 40% to 44.9%, the adjusted hazard ratios for mortality were 1.66 for Hct <25%, 1.50 for 25% to 29.9%, 1.28 for 30% to 34.9%, 1.07 for 35% to 39.9%, 1.03 for 45% to 49.9%, and 1.10 for > or = 50%. The association between anemia and mortality was significant in men and women but stronger in men (P = .006 for interaction). Compared to the category 40% to 44.9%, the risk of rehospitalization was increased to 28% (adjusted hazard ratio 1.28, 95% CI 1.15-1.43) in the Hct category 25% to 29.9%. CONCLUSION Anemia is an independent predictor of mortality and of hospitalizations in elderly patients with AF. Studies are needed to assess the effect of treatment of anemia on clinical outcomes.

Feasibility of MRI attenuation correction in cardiac FDG-PET

Background Simultaneous acquisition PET-MRI is a new technology that has the potential to significantly impact diagnostic patient care. Cardiac imaging using PET-MRI offers high signal resolution MRI images superimposed on PET metabolic functional assessment. Specifically, 18Ffluorodeoxyglucose (FDG) PET-MR has the potential to provide both anatomic scar tissue evaluation and information regarding myocardial glucose metabolism. While early brain and soft tissue data have demonstrated that PET specific uptake values (SUVs) obtained using MRI for attenuation correction (AC) are comparable to SUVs obtained using CT AC, SUV measurements of myocardial tissue have not been compared. The objective of this pilot study is to determine the reproducibility of SUVs obtained by PET imaging using an AC µ-map comprised of a dual echo VIBE Dixon MRI sequence instead of CT. Methods

Demonstration of intermittent ischemia and stunning in hibernating myocardium

Intermittent ischemia and stunning appear to characterize hibernating myocardium. In this report, we demonstrate the variable flow abnormalities that may underlie these phenomena. A 72-year-old woman underwent a rest/vasodilator stress ECG-gated Tc-SPECT myocardial perfusion imaging (MPI). Image interpretation was consistent with a large anterior/anteroapical infarction with borderzone ischemia (Figure 1). Three days later, repeat rest/vasodilator MPI using N-ammonia and late gadolinium enhancement imaging (LGE) was performed simultaneously on a PET/MR (Biograph mMR, Siemens) as part of a research protocol to compare the accuracy of ischemia detection between SPECT and PET/MR. PET/MR MPI revealed extensive and severe anterior/anteroapical ischemia without infarction with resting and post-stress anteroapical hypokinesis (Figure 2A, B; Supplementary Movies 13). LGE PET/MR images showed no evidence of infarction in the area of ischemia detected by PET/MR (Figure 2C-E). The constellation of these findings allowed us to speculate that there was myocardial hibernation. Of note, absolute MBF calculated from the PET data demonstrated near similar resting flow values between the hibernating and normal myocardium with a paradoxical reduction in flow in the hibernating territory at stress, indicative coronary steal (Figure 3). Subsequent coronary angiography confirmed high grade LAD disease (Figure 4). This case provides evidence of the various types of flow abnormalities that characterize myocardial hibernation. They include resting hypoperfusion, impaired vasodilator capacity, and coronary steal. These flow abnormalities, either individually or collectively, can result in myocardial ischemia. However, their intermittent nature will lead to myocardial stunning (normal resting perfusion with abnormal resting wall motion). The finding of variable resting flow values based on the differences in the relative SPECT and PET/MR MPI studies is particularly noteworthy as it may impact the accuracy of SPECT and PET viability studies that are based on relative flow assessment.

An alternative isovelocity surface model for quantitation of effective regurgitant orifice area in mitral regurgitation with an elongated orifice application to functional mitral regurgitation.

OBJECTIVES The purpose of this study was to develop and test a simple, clinically practical alternative isovelocity surface (ISVS) model for calculating effective regurgitant orifice area (EROA) in mitral regurgitation (MR) when the regurgitant orifice is elongated, such as in functional MR. BACKGROUND Clinical experience and 3-dimensional imaging suggest that the traditional hemispheric ISVS model used in the conventional proximal isovelocity surface area (PISA) calculation is invalid in certain MR cases and can cause erroneous EROA values. METHODS Our ISVS model consisted of 3 sections of equal radius (R): a cylindrical midsection of length (L) positioned between 2 hemispheroidal end sections. Total ISVS area (T(S)) is equal to 2πR(2) + πLR and EROA is equal to (V(N/)V(CW))T(S), where V(N) is the flow velocity crossing perpendicular to the ISVS, and V(CW) is the peak MR jet velocity by continuous-wave Doppler. This EROA was corrected for any obtuse angle, θ formed by tented leaflets, by multiplying T(S) by a planar factor, (θ/180) or a combination of this planar factor for the cylindrical midsection and the solid-angle factor, 1-cos(θ/2), for the 2 spheroidal end sections. In 24 cases of severe or 3+ functional MR, we calculated EROA using 3 traditional hemispheric surfaces and 3 alternative ISVS models that differed in the leaflet angle correction applied. Results were compared with continuity-based EROA using the standard mitral valve - aortic valve stroke volume method and with predictions based upon theoretical geometric considerations. RESULTS The mean differences between continuity EROA and ISVS area-based EROA for no angle correction, planar correction, or combined angle correction were, respectively, 0.38, 0.32, and 0.28 cm(2) for the 3 spherical surface models and 0.17, 0.018, and -0.012 cm(2) for the 3 alternative 3-section ISVS models. The empiric EROA results with both the traditional spherical and alternative ISVS models agreed well with theoretical geometric predictions. CONCLUSIONS The traditional spherical PISA model underestimates EROA in functional MR. For elongated MR orifices, an ISVS model that mirrors orifice shape yields more accurate EROA values. Correction to the ISVS area for obtuse leaflet angulation improves accuracy of EROA estimation.