Early Use of N-acetylcysteine With Nitrate Therapy in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Segment-Elevation Myocardial Infarction Reduces Myocardial Infarct Size (the NACIAM Trial [N-acetylcysteine in Acute Myocardial Infarction]).

BACKGROUND: Contemporary ST-segment-elevation myocardial infarction management involves primary percutaneous coronary intervention, with ongoing studies focusing on infarct size reduction using ancillary therapies. N-acetylcysteine (NAC) is an antioxidant with reactive oxygen species scavenging properties that also potentiates the effects of nitroglycerin and thus represents a potentially beneficial ancillary therapy in primary percutaneous coronary intervention. The NACIAM trial (N-acetylcysteine in Acute Myocardial Infarction) examined the effects of NAC on infarct size in patients with ST-segment-elevation myocardial infarction undergoing percutaneous coronary intervention. METHODS: This randomized, double-blind, placebo-controlled, multicenter study evaluated the effects of intravenous high-dose NAC (29 g over 2 days) with background low-dose nitroglycerin (7.2 mg over 2 days) on early cardiac magnetic resonance imaging-assessed infarct size. Secondary end points included cardiac magnetic resonance-determined myocardial salvage and creatine kinase kinetics. RESULTS: Of 112 randomized patients with ST-segment-elevation myocardial infarction, 75 (37 in NAC group, 38 in placebo group) underwent early cardiac magnetic resonance imaging. Median duration of ischemia pretreatment was 2.4 hours. With background nitroglycerin infusion administered to all patients, those randomized to NAC exhibited an absolute 5.5% reduction in cardiac magnetic resonance-assessed infarct size relative to placebo (median, 11.0%; [interquartile range 4.1, 16.3] versus 16.5%; [interquartile range 10.7, 24.2]; P=0.02). Myocardial salvage was approximately doubled in the NAC group (60%; interquartile range, 37-79) compared with placebo (27%; interquartile range, 14-42; P<0.01) and median creatine kinase areas under the curve were 22 000 and 38 000 IU·h in the NAC and placebo groups, respectively (P=0.08). CONCLUSIONS: High-dose intravenous NAC administered with low-dose intravenous nitroglycerin is associated with reduced infarct size in patients with ST-segment-elevation myocardial infarction undergoing percutaneous coronary intervention. A larger study is required to assess the impact of this therapy on clinical cardiac outcomes. CLINICAL TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry. URL: http://www.anzctr.org.au/. Unique identifier: 12610000280000.

Cardiovascular magnetic resonance-GUIDEd management of mild to moderate left ventricular systolic dysfunction (CMR GUIDE): Study protocol for a randomized controlled trial.

BACKGROUND: The majority of sudden cardiac death (SCD) in patients with heart failure occurs in those with mild-moderate left ventricular (LV) systolic dysfunction (LVEF 36-50%) who under current guidelines are ineligible for primary prevention implantable cardiac defibrillator (ICD) therapy. Recent data suggest that cardiac magnetic resonance (CMR) evidence of replacement fibrosis forms a substrate for malignant arrhythmia and therefore potentially identifies a subgroup at increased risk of SCD. Our hypothesis is that among patients with mild-moderate LV systolic dysfunction, a CMR-guided management strategy for ICD insertion based on the presence of scar or fibrosis is superior to a current strategy of standard care. METHODS/DESIGN: CMR GUIDE is a prospective, multicenter randomized control trial enrolling patients with mild-moderate LV systolic dysfunction and CMR evidence of fibrosis on optimal heart failure therapy. Participants will be randomized to receive either a primary prevention ICD or an implantable loop recorder (ILR). The primary endpoint is the time to SCD or hemodynamically significant ventricular arrhythmia (VF or VT) during an average 4-year follow-up. Secondary endpoints include quality of life assessed by Minnesota Living with Heart Failure Questionnaire, heart failure related hospitalizations, and a cost-utility analysis. Clinical trials.gov identifier NCT01918215. DISCUSSION: CMR GUIDE trial will add substantially to our understanding of the role of myocardial fibrosis and the risk of developing life-threatening ventricular arrhythmias. If the superiority of a CMR-guided approach over standard care is proven, it may change international clinical guidelines, with the potential to considerably increase survival in this growing patient population.

Myocardial perfusion is impaired in asymptomatic renal and liver transplant recipients: a cardiovascular magnetic resonance study.

BACKGROUND: Myocardial ischemia is a major cause of death in chronic kidney disease (CKD) patients, which can be caused by either epicardial or microvascular coronary artery disease (CAD). Although renal transplantation improves survival, cardiovascular disease remains a major cause of mortality in post renal transplant recipients, including those with no significant epicardial CAD pre-transplant. We aim to utilize stress cardiovascular magnetic resonance (CMR) and MR coronary angiography (MRCA) to assess silent myocardial ischemia and epicardial CAD in renal transplant recipients. METHODS: Forty-five subjects: twenty renal transplant (RT) with no known CAD, fifteen liver transplant (LT) controls without prior CKD and no known CAD, and ten hypertensive (HT) controls underwent stress perfusion CMR and MRCA. RESULTS: A total of 1308 myocardial segments (576 of RT, 468 of LT, and 264 of HT) were compared using mixed linear modeling. Left ventricular mass index, septal diameter and presence of diabetes mellitus were similar between the groups. The mean transmural MPRI was significantly lower in the RT and LT groups compared to HT controls (1.19 ± 0.50 in RT versus 1.23 ± 0.36 in LT versus 2.04 ± 0.32 in HT controls, p < 0.0001), in the subepicardium (1.33 ± 0.57 in RT versus 1.30 ± 0.33 in LT versus 2.01 ± 0.30 in HT controls, p < 0.001), and in the subendocardium (1.19 ± 0.54 in RT versus 1.11 ± 0.31 in LT versus 1.85 ± 0.34 in HT controls, p < 0.0001). Seven (35%) RT and five (33%) LT had significant epicardial CAD compared to none in HT controls, p = 0.12. One RT and one LT had LGE suggesting sub-endocardial infarction. CONCLUSIONS: RT recipients have impaired myocardial perfusion independent of LVH or diabetes mellitus. The impaired myocardial perfusion in RT is similar to LT without prior renal disease, thus unlikely related to previous CKD. It is not fully explained by the presence of significant epicardial CAD, and therefore most likely represents microvascular CAD.

Utility of CMR Markers of Myocardial Injury in Predicting LV Functional Recovery: Results from PROTECTION AMI CMR Sub-study.

BACKGROUND: Adverse left ventricular (LV) remodelling following acute ST-segment elevation myocardial infarction (STEMI) has prognostic importance. We aimed to predict 90-day left ventricular (LV) function following acute STEMI using variables from clinical presentation, biomarkers, and cardiovascular magnetic resonance imaging (CMR). METHODS: Consecutive patients undergoing primary percutaneous coronary intervention for anterior STEMI as part of the Selective Inhibition of Delta-protein Kinase C for the Reduction of Infarct Size in Acute Myocardial Infarction (PROTECTION-AMI) trial were enrolled into the CMR sub-study at selected sites. CMR was performed at baseline (days 3 to 5) and 90 days and used to evaluate infarct size, myocardial salvage index, infarct heterogeneity, microvascular obstruction and global LV function. Biochemical markers including creatinine kinase area under the curve (CK AUC), peak CK, peak CK-myocardial band (CK-MB) and AUC, and troponin I were collected at specific time-points. RESULTS: Ninety-six patients were enrolled in the CMR sub study and 85 completed the 90-day follow-up, across 24 centres worldwide. LV ejection fraction (EF) was 56% (46-63%) at baseline and 60% (49-67%) at 90 days (p<0.001). Infarct size had moderate inverse correlation with 90-day EF (Spearman's rho=-0.7, p < 0.001) and had the strongest correlation when compared to myocardial salvage index (Spearman's rho=0.5, p=0.001), infarct heterogeneity (Spearman's rho=-0.4, p=0.02 or microvascular obstruction (Spearman's rho=-0.4, p<0.001). All biochemical markers had similar moderate relationship to LVEF at 90 days (Spearman's rho -0.6 to -0.8, p=0.001). In a multivariable model, only baseline LVEF, CMR infarct size and infarct heterogeneity independently predicted 90-day LVEF. CONCLUSION: This study reports findings of a combined CMR protocol (including myocardial oedema imaging) in a multi-centre, multi-vendor setting. We found infarct size, infarct heterogeneity and myocardial salvage index correlated favourably with 90-day LVEF, however only the former two were independently predictive.

A rare case report of type 1 congenital disorders of glycosylation with acute decompensated heart failure and the incidental discovery of congenital disorders of glycosylation associated dilated cardiomyopathy and acute myocarditis.

Background: Congenital disorders of glycosylation (CDG) are rare genetically inherited defects leading to enzyme deficiency or malfunction in the glycosylation pathway. Normal glycosylation is essential to the development of normal cardiac anatomy and function. Congenital disorders of glycosylation-related cardiomyopathy are often the first manifestation detected in early life and may lead to sudden cardiac death. Approximately one-fifth of CDG types are related to cardiac diseases that include cardiomyopathy, rhythm disturbances, pericardial effusions, and structural heart disease. Case summary: We report a rare case of a 26-year-old lady with CDG-1 who presented with acute-onset dyspnoea. She had respiratory tract symptoms for the past 2 weeks. With the relevant clinical and biochemical findings, including supportive findings on echocardiogram and cardiac magnetic resonance imaging, we have managed to arrive at a diagnosis of severe pneumonia leading to acute decompensated heart failure, as well as the discovery of an underlying CDG-associated dilated cardiomyopathy (DCM) and acute myocarditis. Anti-failure medications and i.v. methylprednisolone were commenced, and she showed gradual clinical improvement with an increase of her left ventricular function. She was discharged home well with anti-failure therapy, prednisolone, and a follow-up echocardiogram with further review in the heart failure clinic. Discussion: In conclusion, this case report highlights the need for accurate diagnosis and prompt management of CDG-associated DCM, leading to a successful recovery and discharge from hospital care. With this, we hope to add to the increasing number of reported cases of CDG-related cardiac disease in the medical literature to emphasize the importance of screening and follow-up for any underlying cardiac diseases in patients with CDG.

Cardiovascular magnetic resonance of total and atrial pericardial adipose tissue: a validation study and development of a 3 dimensional pericardial adipose tissue model.

BACKGROUND: Recently pericardial adipose tissue (PAT) has been shown to be an independent predictor of atrial fibrillation (AF). Atrial PAT may influence underlying atrial musculature creating a substrate for AF. This study sought to validate the assessment of total and atrial PAT by standard cardiovascular magnetic resonance (CMR) measures and describe and validate a three dimensional atrial PAT model. METHODS: 10 merino cross sheep underwent CMR using a 1.5 Tesla system (Siemens, Sonata, Erlangen, Germany). Atrial and ventricular short axis (SA) images were acquired, using ECG -gated steady state free precession sequences. In order to quantify total volume of adipose tissue, a three dimensional model was constructed from consecutive end-diastolic images using semi-automated software. Regions of adipose tissue were marked in each slice followed by linear interpolation of pixel intensities in spaces between consecutive image slices. Total volume of adipose tissue was calculated as a total volume of the three dimensional model and the mass estimated from volume measurements. The sheep were euthanized and pericardial adipose tissue was removed and weighed for comparison to the corresponding CMR measurements. RESULTS: All CMR adipose tissue estimates significantly correlated with autopsy measurements (ICC > 0.80; p < 0.03). Intra- observer reliability in CMR measures was high, with 95% levels of agreement within 5.5% (ICC = 0.995) for total fat mass and its individual atrial (95% CI ± 8.3%, ICC = 0.993) and ventricular components (95% CI ± 6.6%, ICC = 0.989). Inter- observer 95% limits of agreement were within ± 10.7% (ICC = 0.979), 7.4% (ICC = 0.991) and 7.2% (ICC = 0.991) for atrial, ventricular and total pericardial adipose tissue, respectively. CONCLUSION: This study validates the use of a semi-automated three dimensional atrial PAT model utilizing standard (clinical) CMR sequences for accurate and reproducible assessment of atrial PAT. The measurement of local cardiac fat stores via this methodology could provide a sensitive tool to examine the regional effect of fat deposition on atrial substrate which potentially may influence AF ablation strategies in obese patients.

Nonvolumetric echocardiographic indices of right ventricular systolic function: validation with cardiovascular magnetic resonance and relationship with functional capacity.

PURPOSE: Right ventricular (RV) systolic function as measured by right ventricular ejection fraction (RVEF) has long been recognized as an important predictor of outcome in heart failure patients. The echocardiographic measurement of RV volumes and RVEF is challenging, however, owing to the unique geometry of the right ventricle. Several nonvolumetric echocardiographic indices of RV function have demonstrated prognostic value in heart failure. Comparison studies of these techniques with each other using RVEF as a benchmark are limited, however. Furthermore, the contribution of these various elements of RV function to patient functional status is uncertain. We therefore aimed to: (1) Determine which nonvolumetric echocardiographic index correlates best with RVEF as determined by cardiac magnetic resonance (CMR) imaging (the accepted gold standard measure of RV systolic function) and (2) Ascertain which echocardiographic index best predicts functional capacity. METHODS: Eighty-three subjects (66 with systolic heart failure and 17 healthy controls) underwent CMR, 2D echocardiography, and cardiopulmonary exercise testing for comparison of echocardiographic indices of RV function with CMR RVEF, 6-minute walk distance and VO(2 PEAK). RESULTS: Speckle tracking strain RV strain exhibited the closest association with CMR RV ejection fraction. Indices of RV function demonstrated weak correlation with 6-minute walk distance, but basal RV strain rate by tissue velocity imaging had good correlation with VO(2 PEAK). CONCLUSION: Strain by speckle tracking echocardiography and strain rate by tissue velocity imaging may offer complementary information in the evaluation of RV contractility and its functional effects.

Myocardial viability imaging: does it still have a role in patient selection prior to coronary revascularisation?

Patients with severe left ventricular (LV) dysfunction and multi-vessel coronary artery disease (CAD) are at high risk during revascularisation, however they are also likely to derive the most benefit. Historically, the detection of dysfunctional but potentially viable myocardium ('stunned or hibernating myocardium') has been central to the decision-making regarding revascularisation. A number of recent studies have challenged this paradigm, questioning the role of viability testing in this population. In this review, we will examine the position of viability testing and how it is best incorporated in the modern era of coronary revascularisation. We will outline the role of currently available imaging modalities in viability assessment. Myocardial viability testing will continue to play a role in revascularisation decisions, although larger randomised trials with clinical outcome end-points are needed to further define its role.

Long-term clinical outcomes in patients with a working diagnosis of myocardial infarction with non-obstructed coronary arteries (MINOCA) assessed by cardiovascular magnetic resonance imaging.

BACKGROUND: Myocardial infarction with non-obstructed coronary arteries (MINOCA) is a distinct entity among patients presenting with troponin-positive acute chest pain. We have previously reported on the incremental diagnostic capability of cardiovascular magnetic resonance (CMR) in this cohort. There is paucity of evidence on the long-term (> 5 years) clinical outcomes of these patients as graded by their acute CMR diagnosis. METHODS AND RESULTS: A total of 229 patients with a working diagnosis of MINOCA who underwent CMR assessment during the acute admission (2010-2017) were prospectively studied. The primary endpoint was major adverse cardiac events (MACE) defined as a composite of all-cause mortality and cardiovascular readmissions, identified from hospital and primary care records. CMR performed at a median of 6 days (IQR 2, 8) from presentation provided a diagnosis in 85% of the patients (38% myocarditis, 28% acute myocardial infarction and 19% Takotsubo cardiomyopathy). Over a median follow-up of 7.1 years (IQR 3.7, 8.2), 56 (24%) patients experienced a MACE. We found a strong association between CMR diagnosis and MACE (log rank 30.47, p < 0.001). In multivariate analysis, age (hazard ratio = 1.07; 95% confidence interval = 1.05, 1.10; p < 0.001) and CMR diagnosis of acute myocardial infarction (hazard ratio = 8.87; 95% confidence interval = 2.58, 30.4; p = 0.001) were independent predictors of MACE. CONCLUSIONS: In a large cohort of patients with a working diagnosis of MINOCA, one in four suffer a MACE during long-term clinical follow-up. CMR diagnosis of acute myocardial infarction and age were significant predictors of MACE even in the absence of significant coronary artery obstruction.

Cardiotoxicity after cancer treatment: a process map of the patient treatment journey.

BACKGROUND/AIM: Cardiotoxicity is a potential complication of anticancer therapy. While guidelines have been developed to assist practitioners, an effective, evidence based clinical pathway for the treatment of cardiotoxicity has not yet been developed. The aim of this study was to describe the journey of patients who developed cardiotoxicity through the healthcare system in order to establish baseline data to inform the development and implementation of a patient-centred, evidence-based clinical pathway. METHODS: Mixed-methods design with quantitative and qualitative components using process mapping at 3 large medical centres in 2 states between 2010 and 2015. RESULTS: Fifty (50) confirmed cases of cardiotoxicity were reviewed (39 medical record reviews, 7 medical record review and interviews and 4 internview only). The mean age at cancer diagnosis of this group was 53.3 years (range 6-89 years); 50% female; 30% breast cancer, 23% non-Hodgkin's lymphoma; mean chemotherapy cycles 5.2 (median 6; range 1-18); 49 (89%) presented to chemotherapy with pre-existing cardiovascular risk factors; 39 (85%) had at least one modifiable risk factor and 11 (24%) had more than 4; 44 (96%) were diagnosed by echocardiogram and 27 (57%) were referred to a cardiologist (only 7 (15%) before chemotherapy). Post chemotherapy, 22 (48%) patients were referred to a multidisciplinary heart failure clinic; 8 (17%) to cardiac rehabilitation; 1 (2%) to cancer survivorship clinic and 10 (22%) to a palliative care service. There were 16 (34%) deaths during the timeframe of the study; 4 (25%) cardiac-related, 6 (38%) cancer-related, 4 (25%) due to sepsis and 2 (12%) other causes not recorded. The main concerns participants raised during the interviews were cancer professionals not discussing the potential for cardiotoxicity with them prior to treatment, nor risk modification strategies; a need for health education, particularly regarding risks for developing heart failure related to cancer treatment; and a lack of collaboration between oncologists and cardiologists. CONCLUSIONS: Our results demonstrate that the clinical management of cancer patients with cardiotoxicity was variable and fragmented and not patient centered. This audit establishes practice gaps that can be addressed through the design of an evidence-based clinical pathway for cancer patients with, or at risk, of cardiotoxicity.

Assessment of myocardial oxygenation, strain, and diastology in MYBPC3-related hypertrophic cardiomyopathy: a cardiovascular magnetic resonance and echocardiography study.

AIMS: Myocardial oxygenation is impaired in hypertrophic cardiomyopathy (HCM) patients with left ventricular hypertrophy (LVH), and possibly also in HCM gene carriers without LVH. Whether these oxygenation changes are also associated with abnormalities in diastolic function or left ventricular (LV) strain are unknown. METHODS AND RESULTS: We evaluated 60 subjects: 20 MYBPC3 gene positive patients with LVH (G+LVH+), 18 MYBPC3 gene positive without LVH (G+LVH-), 11 gene negative siblings (G-), and 11 normal controls (NC). All subjects underwent 2D transthoracic echocardiography and cardiovascular magnetic resonance imaging for assessment of ventricular volumes, mass, and myocardial oxygenation at rest and adenosine stress using the blood oxygen level dependent (BOLD) technique. Maximal septal thickness was 20 mm in the G+LVH+ group, vs. 9 mm for the G+LVH- group. As expected, the G+LVH+ group had a more blunted myocardial oxygenation response to stress when compared with the G+LVH- group (-5% ± 3% vs. 2% ± 4%, P < 0.05), G- siblings (-5% ± 3% vs. 11% ± 4%, P < 0.0001) and NC (-5% ± 3% vs. 15% ± 4%, P < 0.0001). A blunted BOLD response to stress was also seen in G+LVH- subjects when compared with gene negative siblings (2% ± 4% vs. 11% ± 4%, P < 0.05) and NC (15% ± 4%, P < 0.050). G+LVH+ patients exhibited abnormal diastolic function including lower E', higher E to E' ratio and greater left atrial area compared with the G+LVH- subjects who all had normal values for these indices. CONCLUSION: Myocardial deoxygenation during stress is observed in MYBPC3 HCM patients, even in the presence of normal LV diastolic function, LV global longitudinal strain, and LV wall thickness.

Late characterisation of cardiac effects following anthracycline and trastuzumab treatment in breast cancer patients.

BACKGROUND: Anthracycline (A) and trastuzumab (T) chemotherapy have well-recognized cardiac toxicity, potentially leading to significant morbidity and mortality. Our previous work in 46 prospectively enrolled breast cancer patients showed early left ventricular (LV) and right ventricular (RV) function decline at 1 and 3 months, but only persistent RV dysfunction at 12 months which correlated with myocardial oedema observed early (1 and 3 months) after administration of chemotherapy regimes. METHOD: To investigate late cardiac effects, the same cohort were re-imaged with advanced Cardiovascular Magnetic Resonance (CMR) imaging including T1 mapping 5 ±â€¯1 year post chemotherapy. RESULTS: Twenty-six out of 46 (50%) patients underwent follow-up imaging. A statistical but non-clinically significant decrease was observed in LV ejection fraction (EF) from baseline to 5 years (72.2 ±â€¯6.6 to 65.4 ±â€¯9.3, p < 0.005). Subjects with initial drop of LVEF by >10% at 3 months (n = 5) or at 12 months (n = 3) did not demonstrate any difference in LV or RVEF at 5 years. No correlation was observed between myocardial oedema and LV or RVEF at 5 years. At 5 years, T1 values were within normal limits overall (935 ±â€¯48 ms). One patients had significantly elevated (>1000 ms) T1 values with no correlation to LV or RVEF. No subjects demonstrated replacement myocardial fibrosis at 5 years. CONCLUSION: Using advanced CMR, contemporary chemotherapy regimes demonstrate minimal long-term cardiac toxicity. There is minimal diffuse and no replacement fibrosis as demonstrated by LGE, following chemotherapy. This study suggests limiting serial imaging in these patients at 12 months post chemotherapy.

Troponin-positive chest pain with unobstructed coronary arteries: incremental diagnostic value of cardiovascular magnetic resonance imaging.

AIMS: Troponin-positive chest pain patients with unobstructed coronaries represent a clinical dilemma. Cardiovascular magnetic resonance (CMR) imaging has an increasingly prominent role in the assessment of these patients; however, its utility in addition to expert clinical judgement is unclear. We sought to determine the incremental diagnostic value of CMR and the heterogeneity in diagnoses by experienced cardiologists when presented with blinded clinical and investigative data in this population. METHODS AND RESULTS: A total of 125 consecutive patients presenting to a tertiary centre between 2010 and 2014 with cardiac chest pain, elevated troponin (>29 ng/L), and unobstructed coronaries were enrolled and underwent CMR. A panel of three experienced cardiologists unaware of the CMR diagnosis and blinded to each other's assessment provided a diagnosis based on clinical and investigative findings. A consensus panel diagnosis was defined as two or more cardiologists sharing the same clinical diagnosis. Findings were classified into acute myocarditis, Takotsubo cardiomyopathy, acute myocardial infarction (AMI), or indeterminate. CMR provided a diagnosis in 87% of patients. Consensus panel diagnosis and CMR were concordant in 65/125 (52%) patients. There was an only moderate level of agreement between the three cardiologists (k = 0.47, P < 0.05) and a poor level of agreement between the consensus panel and CMR (k = 0.38, P < 0.05) with the most disagreement seen in patients with AMI diagnosed on CMR. CONCLUSION: The clinical diagnosis of patients with non-obstructive coronaries and positive troponin remains a challenge. The concordance between CMR and clinical diagnosis is poor. CMR provides a diagnosis in majority of these patients.

Impaired Myocardial Oxygenation Response to Stress in Patients With Chronic Kidney Disease.

BACKGROUND: Coronary artery disease and left ventricular hypertrophy are prevalent in the chronic kidney disease (CKD) and renal transplant (RT) population. Advances in cardiovascular magnetic resonance (CMR) with blood oxygen level-dependent (BOLD) technique provides capability to assess myocardial oxygenation as a measure of ischemia. We hypothesized that the myocardial oxygenation response to stress would be impaired in CKD and RT patients. METHODS AND RESULTS: Fifty-three subjects (23 subjects with CKD, 10 RT recipients, 10 hypertensive (HT) controls, and 10 normal controls without known coronary artery disease) underwent CMR scanning. All groups had cine and BOLD CMR at 3 T. The RT and HT groups also had late gadolinium CMR to assess infarction/replacement fibrosis. The CKD group underwent 2-dimensional echocardiography strain to assess fibrosis. Myocardial oxygenation was measured at rest and under stress with adenosine (140 µg/kg per minute) using BOLD signal intensity. A total of 2898 myocardial segments (1200 segments in CKD patients, 552 segments in RT, 480 segments in HT, and 666 segments in normal controls) were compared using linear mixed modeling. Diabetes mellitus (P=0.47) and hypertension (P=0.57) were similar between CKD, RT, and HT groups. The mean BOLD signal intensity change was significantly lower in the CKD and RT groups compared to HT controls and normal controls (-0.89±10.63% in CKD versus 5.66±7.87% in RT versus 15.54±9.58% in HT controls versus 16.19±11.11% in normal controls, P<0.0001). BOLD signal intensity change was associated with estimated glomerular filtration rate (ß=0.16, 95% CI=0.10 to 0.22, P<0.0001). Left ventricular mass index and left ventricular septal wall diameter were similar between the CKD predialysis, RT, and HT groups. None of the CKD patients had impaired global longitudinal strain and none of the RT group had late gadolinium hyperenhancement. CONCLUSIONS: Myocardial oxygenation response to stress is impaired in CKD patients and RT recipients without known coronary artery disease, and unlikely to be solely accounted for by the presence of diabetes mellitus, left ventricular hypertrophy, or myocardial scarring. The impaired myocardial oxygenation in CKD patients may be associated with declining renal function. Noncontrast BOLD CMR is a promising tool for detecting myocardial ischemia in the CKD population.

Mapping and ablation of the pulmonary veins and cavo-tricuspid isthmus with a magnetic resonance imaging-compatible externally irrigated ablation catheter and integrated electrophysiology system.

BACKGROUND: Magnetic resonance imaging (MRI)-guided interventional electrophysiology (EP) has rapidly emerged as a promising alternative to x-ray-guided ablation. We aimed to evaluate an externally irrigated MRI-compatible ablation catheter and integrated EP pacing and recording system, testing the feasibility of pulmonary vein and cavo-tricuspid isthmus ablation. METHODS AND RESULTS: Externally irrigated MRI-compatible ablation and diagnostic EP catheters and an integrated EP recording system (Imricor Medical Systems, Burnsville, MN) were tested in n=11 sheep in a 1.5-T MRI scanner. Power-controlled (40 W, 120-second duration) lesions were formed at the pulmonary vein and cavo-tricuspid isthmus. Real-time intracardiac electrograms were recorded during MRI. Steady-state free precession non-breath-hold images were repeatedly acquired to guide catheter navigation. Lesion visualization was performed using noncontrast (T2-weighted turbo spin echo pulse sequence) and gadolinium-diethylene triamine pentaacetic acid-enhanced T1-weighted imaging (inversion-recovery gradient echo pulse sequence). Catheters were able to be visualized and navigated under cardiovascular magnetic resonance guidance. In total, 8±2.5 lesions (radiofrequency time, 16±4.2 minutes) were formed at the pulmonary vein ostia, and 6.5±1.3 lesions (radiofrequency time, 13±2.2 minutes) were formed at the cavo-tricuspid isthmus, with the end point of bidirectional block. The mean procedure time was 150±55 minutes. Lesion visualization with both T2W imaging and contrast-enhanced imaging correlated with sites of injury at autopsy. CONCLUSIONS: These data demonstrate the feasibility of using multiple catheters, an integrated EP pacing and recording system, and externally irrigated ablation with cardiovascular magnetic resonance guidance to undertake clinically relevant biatrial mapping and ablation.

Evaluation of myocardial viability with cardiac magnetic resonance imaging.

Assessment of myocardial viability is of clinical and scientific significance. Traditionally, the detection of myocardial viability (either stunning or hibernation) has been used in aiding diagnosis before revascularization, especially in high-risk patients. There is a considerable body of observational evidence showing substantial improvement after revascularization in patients with significant left ventricular dysfunction and myocardial viability. Recent randomized evidence has questioned the benefit of viability testing but must be interpreted with caution. Dobutamine stress echocardiography, nuclear imaging, and cardiovascular magnetic resonance are the mainstays of viability testing and provide information on contractile function, cellular metabolism, and myocardial fibrosis, respectively. Larger, multicenter trials with outcome data are needed to define the nature of viability testing and, particularly, cardiovascular magnetic resonance in moderate-to-severe ischemic cardiomyopathy.