Cardio-hepatic risk assessment by CMR imaging in liver transplant candidates.

BACKGROUND: The preoperative workup of orthotopic liver transplantation (OLT) patients is practically complex given the need for multiple imaging modalities. We recently demonstrated in our proof-of-concept study the value of a one-stop-shop approach using cardiovascular MRI (CMR) to address this complex problem. However, this approach requires further validation in a larger cohort, as detection of hepatocellular carcinoma (HCC) as well as cardiovascular risk assessment is critically important in these patients. We hypothesized that coronary risk assessment and HCC detectability is acceptable using the one-stop-shop CMR approach. METHODS: In this observational study, patients underwent CMRI evaluation including cardiac function, stress CMR, thoracoabdominal MRA, and abdominal MRI on a standard MRI scanner in one examination. RESULTS: Over 8 years, 252 OLT candidates underwent evaluation in the cardiac MRI suit. The completion rates for each segment of the CMR examination were 99% for function, 95% completed stress CMR, 93% completed LGE for viability, 85% for liver MRI, and 87% for MRA. A negative CMR stress examination had 100% CAD event-free survival at 12 months. A total of 63 (29%) patients proceeded to OLT. Explant pathology confirmed detection/exclusion of HCC. CONCLUSIONS: This study further defines the population suitable for the one-stop-shop CMR concept for preop evaluation of OLT candidates providing a road map for integrated testing in this complex patient population for evaluation of cardiac risk and detection of HCC lesions.

A Benign Cardiac Growth but Not So Indolent.

Cardiac lipomatous hypertrophy is a rare benign condition that usually involves the interatrial septum. Due to its benign nature it rarely requires intervention. Its presence outside the interatrial septum is reported infrequently. We present a case of lipomatous hypertrophy in the intraventricular septum that was complicated by a severe, symptomatic, and disabling dynamic left ventricular outflow tract obstruction. The symptoms significantly improved following the excision of the mass. In our case transthoracic echocardiogram was used to visualize the mass and measure the severity of the obstruction; Cardiac Magnetic Resonance Imaging was used to characterize the mass and histopathology confirmed the diagnosis.

Ex vivo cardiovascular magnetic resonance measurements of right and left ventricular mass compared with direct mass measurement in excised hearts after transplantation: a first human SSFP comparison.

BACKGROUND: CMR is considered the 'gold standard' for non-invasive LV and RV mass quantitation. This information is solely based on gradient-recalled echo (GRE) sequences while contrast dependent on intrinsic T1/T2 characteristics potentially offers superior image contrast between blood and myocardium. This study aims, for the first time in humans, to validate the SSFP approach using explanted hearts obtained from heart transplant recipients. Our objective is establish the correlation between and to validate steady-state free precession (SSFP) derived LV and RV mass vs. autopsy mass of hearts from cardiac transplants patients. METHODS: Over three-years, 58 explanted cardiomyopathy hearts were obtained immediately upon orthotopic heart transplantation from the OR. They were quickly cleaned, prepared and suspended in a saline-filled container and scanned ex vivo via SSFP-SA slices to define LV/RV mass. Using an automatic thresholding program, segmentation was achieved in combination with manual trimming (ATMT) of extraneous tissue incorporating 3D cardiac modeling performed by independent and blinded readers. The explanted hearts were then dissected with the ventricles surgically separated at the interventricular septum. Weights of the total heart not excluding papillary and trabecular myocardium, LV and RV were measured via high-fidelity scale. Linear regression and Bland-Altman plots were used to analyze the data. The intra-class correlation coefficient was used to assess intra-observer reliability. RESULTS: Of the total of 58 explanted hearts, 3 (6%) were excluded due to poor image quality leaving 55 patients (94%) for the final analysis. Significant positive correlations were found between total 3D CMR mass (450 ± 111 g) and total pathology mass (445 ± 116 g; r = 0.99, p < 0.001) as well as 3D CMR measured LV mass (301 ± 93 g) and the pathology measured LV mass (313 ± 96 g; r = 0.95, p < 0.001). Strong positive correlations were demonstrated between the 3D CMR measured RV mass (149 ± 46 g) and the pathology measured RV mass (128 ± 40 g; r = 0.76, p < 0.001). The mean bias between 3D-CMR and pathology measures for total mass, LV mass and RV mass were: 3.0 g, -16 g and 19 g, respectively. CONCLUSIONS: SSFP-CMR accurately determines total myocardial, LV and RV mass as compared to pathology weighed explanted hearts despite variable surgical removal of instrumentation (left and right ventricular assist devices, AICD and often apical core removals). Thus, this becomes the first-ever human CMR confirmation for SSFP now validating the distinction of 'gold standard'.

Evaluation of cardiac valvular regurgitant lesions by cardiac MRI sequences: comparison of a four-valve semi-quantitative versus quantitative approach.

BACKGROUND AND AIM OF THE STUDY: Cardiac magnetic resonance (CMR) imaging generally allows a more accurate and valid quantification of cardiac function, mass and regurgitant volumes than echocardiography. Although recent technological advancements in CMR have made the evaluation of cardiac valves more reliable, no studies have yet been conducted to compare semi-quantitative grading (SQG) using CMR steady-state free precession (SSFP) sequences with quantitative grading (QG) based on stroke volumes and phase-velocity mapping (PVM). It is proposed that the SQG of cardiac valvular regurgitations based on CMR SSFP sequences is feasible, and highly correlative with standard CMR QG methods. METHODS: CMR data obtained between January 2007 and December 2011 was evaluated prospectively for valvular regurgitant lesions. Patients were included if they had right and left ventricular volumetrics based on CMR SSFP sequences and PVM across the aortic and pulmonic valves with reported regurgitant volumes and fractions. Patients were excluded if they had prosthetic valves, cardiac arrhythmias and intra-cardiac shunts. Regurgitant lesions were semi-quantitatively (visually) graded on a standard scale of 0 to 4 (trace, mild, moderate, moderate to severe, and severe) and compared with quantitative regurgitant fractions. Correlations were evaluated by Spearman's rho formula, and kappa for intra- and inter-observer variabilities were obtained on 30% of the study sample. RESULTS: A total of 97 patients (58 males, 39 females; average age 55 +/- 18 years) representing 134 valvular regurgitations [mitral (MR), aortic (AR), tricuspid (TR), and pulmonary (PR)] were analyzed by semiquantitative and quantitative methods. The regurgitant lesions included 44 mitral, 50 aortic, 29 tricuspid, and 11 pulmonary. The correlation between SQR versus QG yielded the following results: 0.67, p < 0.001 (MR, r = 0.66, p < 0.001; AR, r = 0.68, p < 0.002; TR, r = 0.68, p = 0.001; PR, r = 0.70, p = 0.017). The results for QG versus SQG accounting for clinically significant differences of +/- 1 grade for the group were as follows: 0.95, p < 0.001 (MR, r = 0.91, p < 0.001; AR, r = 0.96, p < 0.001; TR, r = 0.99, p < 0.001; PR, r = 0.93, p < 0.001). No discrepancy between surgical regurgitation was present (3+ versus 4+). Weighted kappa results were 0.67 and 0.61 for intra- and inter-observer variabilities. CONCLUSION: The visual assessment of cardiac regurgitant lesions is reliable, accurate and reproducible when compared to formal quantitative analysis via CMR. This confirms a robust role for CMR in assessing regurgitant lesions, particularly for surgical decision-making. These results were applicable to patients in sinus rhythm at the time of scanning.

Exploratory use of cardiovascular magnetic resonance imaging in liver transplantation: a one-stop shop for preoperative cardiohepatic evaluation.

BACKGROUND: Preoperative cardiovascular risk stratification in orthotopic liver transplantation candidates has proven challenging due to limitations of current noninvasive modalities. Additionally, the preoperative workup is logistically cumbersome and expensive given the need for separate cardiac, vascular, and abdominal imaging. We evaluated the feasibility of a "one-stop shop" in a magnetic resonance suite, performing assessment of cardiac structure, function, and viability, along with simultaneous evaluation of thoracoabdominal vasculature and liver anatomy. METHODS: In this pilot study, patients underwent steady-state free precession sequences and stress cardiac magnetic resonance (CMR), thoracoabdominal magnetic resonance angiography, and abdominal magnetic resonance imaging (MRI) on a standard MRI scanner. Pharmacologic stress was performed using regadenoson, adenosine, or dobutamine. Viability was assessed using late gadolinium enhancement. RESULTS: Over 2 years, 51 of 77 liver transplant candidates (mean age, 56 years; 35% female; mean Model for End-stage Liver Disease score, 10.8; range, 6-40) underwent MRI. All referred patients completed standard dynamic CMR, 98% completed stress CMR, 82% completed late gadolinium enhancement for viability, 94% completed liver MRI, and 88% completed magnetic resonance angiography. The mean duration of the entire study was 72 min, and 45 patients were able to complete the entire examination. Among all 51 patients, 4 required follow-up coronary angiography (3 for evidence of ischemia on perfusion CMR and 1 for postoperative ischemia), and none had flow-limiting coronary disease. Nine proceeded to orthotopic liver transplantation (mean 74 days to transplantation after MRI). There were six ascertained mortalities in the nontransplant group and one death in the transplanted group. Explant pathology confirmed 100% detection/exclusion of hepatocellular carcinoma. No complications during CMR examination were encountered. CONCLUSIONS: In this proof-of-concept study, it appears feasible to perform a comprehensive, efficient, and safe preoperative liver transplant imaging in a CMR suite-a one-stop shop, even in seriously ill patients.

Mitral regurgitation recovery and atrial reverse remodeling following pulmonary vein isolation procedure in patients with atrial fibrillation: a clinical observation proof-of-concept cardiac MRI study.

BACKGROUND: Reverse remodeling of the left atrium (LA) following successful pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) has been well documented. However, mitral regurgitation (MR) recovery after successful PVI has never been demonstrated systematically. The objective of our study was to retrospectively analyze the effectiveness of PVI in patients with AF on recovery of MR using cardiac magnetic resonance (CMR) imaging. METHODS: Prior to PVI, patients underwent a clinically indicated CMR imaging. Post-PVI (6 ± 2 months), patients underwent a follow-up MRI and were classified into two groups-responders (R) and non-responders (NR) to PVI-as assessed by cessation of AF at the end of the prespecified 6-month (14-day "P" sensitive event monitor defined) follow-up period. Furthermore, CMR was used to evaluate the severity of MR (0 to 4+) and to relate changes in MR to LA volumes as well as mitral apparatus geometry. Patients who had mild and higher MR (2+) on baseline CMR and had a post-PVI CMR were selected for final analysis. RESULTS: Out of the consecutive 122 patients with AF who underwent PVI, 74 patients that had mitral regurgitation on initial CMR were included in the study. Of these74 patients with AF with MR, 52 (70 %) were classified as R and 22 (30 %) were classified as NR. Baseline demographics were similar between the groups. In the subgroup with mild to severe MR, pre vs. post in the R group MR severity significantly improved (mean = 2.3, median = 2.0 vs. mean = 1.0, median = 1.0, p < 0.0001) and was matched by favorable reverse remodeling of the mitral apparatus geometry (annulus = 35 ± 4 vs. 33 ± 3 mm, p < 0.002; tenting area = 175 ± 56 vs.137 ± 37 mm(2), p < 0.003; tenting height = 8 ± 2 vs.7 ± 2 mm, p < 0.02; and tenting angle = 129 ± 10° vs. 131 ± 11°, p = 0.1). However, in the NR subgroup, MR failed to improve (mean = 2.2, median = 2.0 vs. mean = 1.5, median = 1.0, p = NS) and paralleled general failure of mitral geometry reverse remodeling (annulus = 35 ± 4 vs. 35 ± 4 mm, p = 0.2; tenting area = 153 ± 39 vs. 152 ± 34 mm(2), p = NS; tenting height = 7 ± 1 vs. 7.0 ± 2, p = 0.1; and tenting angle = 131 ± 11° vs. 133 ± 10°, p = NS). In those with lesser degrees of MR, favorable remodeling was predicated on responder status to PVI. Similarly, other cardiac dimensions pre- to post-PVI favorably improved in the R group, but not in the NR group. CONCLUSION: In those with durable maintenance of normal sinus rhythm (NSR), cardiac reverse remodeling demonstrated by 3D CMR occurs and is matched by marked improvements in MR and mitral apparatus, likely contributing to continued maintenance of NSR.

Contrast-enhanced CMR is equally effective as TEE in the evaluation of left atrial appendage thrombus in patients with atrial fibrillation undergoing pulmonary vein isolation procedure.

BACKGROUND: Patients with atrial fibrillation (AF) routinely undergo transesophageal echocardiography (TEE) for the evaluation of the left atrial appendage (LAA) to rule out thrombus prior to undergoing pulmonary vein isolation (PVI). Cardiac magnetic resonance (CMR) is now increasingly used for the evaluation of patients with AF to define pulmonary vein (PV) anatomy prior to PVI. OBJECTIVE: To hypothesize that a retrospective comparison of 2-dimensional/3-dimensional (2D/3D) contrast-enhanced CMR sequences with TEE for the evaluation of LAA thrombus in patients with AF selected for PVI will demonstrate equivalence. METHODS: Ninety-seven (N = 97) consecutive patients with AF underwent near-simultaneous TEE and noncontrast and contrast CMR prior to undergoing an initial PVI procedure. The CMR images were analyzed in 2 categories: (1) the 2D noncontrast cine images and early gadolinium enhancement images showing LAA and (2) 3D contrast source images acquired during PV magnetic resonance angiography. CMR variables evaluated were the presence or absence of LAA thrombus and the quality of images, and they were compared with the results of TEE in a blinded fashion. RESULTS: All subjects were analyzed for the presence or absence of LAA thrombus. Thrombus was absent in 98% of the patients on both TEE and CMR and present in 2% on both studies (100% correlation). In 6 subjects, 2D cine CMR images were indeterminate whereas all 2D early gadolinium enhancement images and 3D contrast images were successful in excluding LAA thrombus. There was 100% concordance between CMR and TEE for the final diagnosis of LAA thrombus. CONCLUSIONS: In one single examination, CMR offers a comparable alternative to TEE for the complete noninvasive evaluation of LAA thrombus and PV anatomy in patients with AF referred for PVI without obligate need for TEE.

Simultaneous hypertrophic cardiomyopathy and muscular ventricular septal defect in an adult patient.

BACKGROUND: The incidence of muscular ventricular septal defect (VSD) in children is rare, but its prevalence among hypertrophic cardiomyopathy (HCM) patients is surprisingly high. METHODS: We present a 24-year-old female with HCM associated with muscular VSD without significant symptoms or hemodynamic implications. CONCLUSION: Cardiac magnetic resonance imaging plays an important role in anatomic and functional noninvasive evaluation of these patients.