Objectives To assess the prognostic value of global magnetic resonance (MR) myocardial perfusion imaging (MPI) in women with suspected myocardial ischemia and no obstructive (stenosis <50%) coronary artery disease (CAD). Background The prognostic value of global MR-MPI in women without obstructive CAD remains unknown. Methods Women (n=100, mean age 57±11 years, range 31–76), with symptoms of myocardial ischemia and with no obstructive CAD as assessed by coronary angiography, underwent MR-MPI and standard functional assessment. During follow-up (34±16 months), time to first adverse event (death, myocardial infarction or hospitalization for worsening anginal symptoms) was analyzed using global MPI and left ventricular ejection fraction (EF) data. Results Adverse events occurred in 23 (23%). By univariable Cox proportional hazards regression modeling, variables found to be predictive of adverse events were global MR-MPI average uptake slope (p<0.05), the ratio of MR-MPI peak signal amplitude to uptake slope (p<0.05), and ejection fraction (EF) (p<0.05). Two multivariable Cox models were formed, one using variables that are performance-site dependent: ratio of MR-MPI peak amplitude to uptake slope together with EF (Chi-squared 13, p<0.005), and a model using variables that are performance-site independent: MR-MPI slope and EF (Chi-squared 12, p<0.005). Each of the two multivariable models remained predictive of adverse events after adjustment for age, disease history and Framingham risk score. For each of the Cox models, patients were categorized as high-risk if they were in the upper quartile of the model and not high-risk otherwise. Kaplan-Meier analysis of time to event was performed for high-risk vs. not high-risk for site-dependent (log rank 15.2, p<0.001) and site-independent (log rank 13.0, p<001) models. Conclusions Among women with suspected myocardial ischemia and no obstructive CAD, MR-MPI determined global measurements of normalized uptake slope and peak signal uptake, together with global functional assessment of EF appear to predict prognosis.
BackgroundCMR 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.MethodsOver 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.ResultsOf 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.ConclusionsSSFP-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’.
BackgroundIn patients with severe aortic stenosis (AS), long-term data tracking surgically induced effects of afterload reduction on reverse LV remodeling are not available. Echocardiographic data is available short term, but in limited fashion beyond one year. Cardiovascular MRI (CMR) offers the ability to serially track changes in LV metrics with small numbers due to its inherent high spatial resolution and low variability.HypothesisWe hypothesize that changes in LV structure and function following aortic valve replacement (AVR) are detectable by CMR and once triggered by AVR, continue for an extended period.MethodsTweny-four patients of which ten (67 ± 12 years, 6 female) with severe, but compensated AS underwent CMR pre-AVR, 6 months, 1 year and up to 4 years post-AVR. 3D LV mass index, volumetrics, LV geometry, and EF were measured.ResultsAll patients survived AVR and underwent CMR 4 serial CMR's. LVMI markedly decreased by 6 months (157 ± 42 to 134 ± 32 g/m2, p < 0.005) and continued trending downwards through 4 years (127 ± 32 g/m2). Similarly, EF increased pre to post-AVR (55 ± 22 to 65 ± 11%,(p < 0.05)) and continued trending upwards, remaining stable through years 1-4 (66 ± 11 vs. 65 ± 9%). LVEDVI, initially high pre-AVR, decreased post-AVR (83 ± 30 to 68 ± 11 ml/m2, p < 0.05) trending even lower by year 4 (66 ± 10 ml/m2). LV stroke volume increased rapidly from pre to post-AVR (40 ± 11 to 44 ± 7 ml, p < 0.05) continuing to increase non-significantly through 4 years (49 ± 14 ml) with these LV metrics paralleling improvements in NYHA. However, LVmass/volume, a 3D measure of LV geometry, remained unchanged over 4 years.ConclusionAfter initial beneficial effects imparted by AVR in severe AS patients, there are, as expected, marked improvements in LV reverse remodeling. Via CMR, surgically induced benefits to LV structure and function are durable and, unexpectedly express continued, albeit markedly incomplete improvement through 4 years post-AVR concordant with sustained improved clinical status. This supports down-regulation of both mRNA and MMP activity acutely with robust suppression long term.
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