Cardiovascular Magnetic Resonance, Fibrosis, and Prognosis in Dilated Cardiomyopathy

Comparison of cardiovascular magnetic resonance of late gadolinium enhancement and diastolic wall thickness to predict recovery of left ventricular function after coronary artery bypass surgery

BACKGROUND

The objective was to compare the value of late gadolinium enhancement (LGE) and end-diastolic wall thickness (EDWT) assessed by cardiovascular magnetic resonance (CMR) in predicting recovery of left ventricular function after coronary artery bypass surgery (CABG).

METHODS

We enrolled patients with coronary artery disease and left ventricular ejection fraction < 45% who were scheduled for CABG. Regional contractility was assessed by cine CMR at baseline and 4 months after CABG. EDWT and LGE were assessed at baseline. Predictors for improvement of regional contractility were analyzed.

RESULTS

We studied 46 men and 4 women with an average age of 61 years. Baseline left ventricular ejection fraction was 37 +/- 13%. A total of 2,020 myocardial segments were analyzed. Abnormal wall motion and the LGE area were detected in 1,446 segments (71.6%) and 1,196 segments (59.2%) respectively. Wall motion improvement was demonstrated in 481 of 1,227 segments (39.2%) that initially had wall motion abnormalities at baseline. Logistic regression analysis showed that the LGE area, EDWT and resting wall motion grade predicted wall motion improvement. Comparison of Receiver-Operator-Characteristic (ROC) curves demonstrated that the LGE area was the most important predictor (p < 0.001). Adding information from LGE to the EDWT can decrease the number of false predictions by EDWT alone from 483 to 127 segments.

CONCLUSION

LGE and EDWT are independent predictors for functional recovery after revascularization. However, LGE appears to be a more important factor and independent of EDWT.

Magnetic resonance reveals long-term sequelae of apical ballooning syndrome

BACKGROUND

The presence of small areas of necrosis has been occasionally reported immediately following apical ballooning syndrome (ABS). However, their persistence at later stages and impact on long-term prognosis are currently unknown.

METHODS

Twenty consecutive patients admitted for ABS between 2004 and 2007 were prospectively evaluated. Demographic, clinical, angiographic, and echocardiographic data were collected during hospital admission. At a mean of 11+/-9 months follow-up, a contrast enhanced cardiac magnetic resonance (ce-CMR) study was performed in 17 cases. The presence of hyperenhancement on ce-CMR images, reflecting irreversible myocardial damage, was recorded by two independent observers.

RESULTS

Two of 3 patients with hyperenhancement on ce-CMR images presented in worse condition, including pulmonary edema or cardiogenic shock, compared to just 2 of 14 patients without hyperenhancement (p=0.052). Segmental wall motion substantially improved in both of those cases; the third patient continued to have hypokinesis in a segment showing hyperenhancement. Segmental wall motion also significantly improved in all patients with no hyperenhancement. At a mean of 20+/-12 months follow-up, no deaths or major adverse cardiac events were documented among patients with or without hyperenhancement.

CONCLUSIONS

Despite segmental wall motion recovery, an area of irreversible myocardial damage can sometimes be identified long after ABS. However, in this limited series of patients, the presence of scar, even when presenting with heart failure and a higher troponin release, was not associated with adverse long-term outcomes as compared to patients with intact myocardium.

Extensive venous thrombosis and cardiomyopathy demonstrated with cardiovascular magnetic resonance

We describe a patient who presented with typical symptoms of submassive pulmonary embolism associated with newly diagnosed cardiomyopathy. Contrast enhanced computed tomography demonstrated extensive venous thrombosis, and late enhancement cardiovascular magnetic resonance imaging was consistent with dilated cardiomyopathy with midwall fibrosis. We discuss the images and aetiology of the cardiomyopathy.

Cardiac MR imaging of nonischemic cardiomyopathies

Cardiomyopathies, diseases of the myocardium associated with cardiac dysfunction, include hypertrophic, restrictive, and dilated forms and rare entities, such as arrhythmogenic right ventricular dysplasia, ventricular noncompaction, and apical ballooning syndrome. Many have similar presentations, but the underlying condition determines prognoses and treatment. Cardiac MR imaging plays a role in characterizing the range of entities and is crucial for evaluation and management. In addition, delayed enhanced imaging can allow differentiation among the forms of cardiomyopathy and offer prognostic information. As the speed and technical ease of cardiac imaging improve, MR imaging will assume an increasing role in the care of patients who have cardiomyopathy.

Combined coronary and late-enhanced multidetector-computed tomography for delineation of the etiology of left ventricular dysfunction: comparison with coronary angiography and contrast-enhanced cardiac magnetic resonance imaging

Aims

To evaluate whether comprehensive evaluation of coronary anatomy and delayed enhancement (DE) by multidetector-computed tomography (MDCT) would allow determination of etiology of left ventricular dysfunction (LVD) as compared with coronary angiography (CA) and DE-magnetic resonance (CMR).

Methods and results

Seventy-one consecutive patients (50 males, 59 ± 16 years) with LVD (ejection fraction: 26 ± 11%) of unknown etiology underwent MDCT, LGE (late Gd-DTPA-enhanced)-CMR and CA. Patients were classified into four groups according to coronary artery disease (CAD) by CA and LGE-CMR patterns. Patients (n = 24) with CAD and transmural or sub-endocardial DE by CMR were considered having definite ischaemic LVD (group 1). Patients (n = 36) without CAD by CA and with no/atypical LGE-CMR were considered non-ischaemic LVD (group 2). Further we identified four patients with transmural DE but no CAD (group 3) and seven patients with CAD but no DE (group 4). On per-patient basis, combined coronary and DE-MDCT had excellent agreement (κ = 0.89; P < 0.001) with CA/LGE-CMR to classify patients into the same four groups. Sensitivity, specificity and accuracy of MDCT were 97, 92 and 94%, respectively for detecting patients with definite (group 1) or likely (groups 3 and 4) ischaemic LVD.

Conclusion

Combined coronary and DE-MDCT can accurately differentiate ischaemic vs. non-ischaemic etiology of LVD.

Cardiac magnetic resonance imaging of myocardial contrast uptake and blood flow in patients affected with idiopathic or familial dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) is characterized by left ventricular (LV) enlargement with systolic dysfunction, other causes excluded. When inherited, it represents familial dilated cardiomyopathy (FDC). We hypothesized that IDC or FDC would show with cardiac magnetic resonance (CMR) increased myocardial accumulation of gadolinium contrast at steady state and decreased baseline myocardial blood flow (MBF) due to structural alterations of the extracellular matrix compared with normal myocardium. CMR was performed in nine persons affected with IDC/FDC. Healthy controls came from the general population (n = 6) or were unaffected family members of FDC patients (n = 3) without signs or symptoms of IDC/FDC or any structural cardiac abnormalities. The myocardial partition coefficient for gadolinium contrast (lambda(Gd)) was determined by T1 measurements. LV shape and function and MBF were assessed by standard CMR methods. lambda(Gd) was elevated in IDC/FDC patients vs. healthy controls (lambda(Gd) = 0.56 +/- 0.15 vs. 0.41 +/- 0.06; P = 0.002), and correlated with LV enlargement (r = 0.61 for lambda(Gd) vs. end-diastolic volume indexed by height; P < 0.01) and with ejection fraction (r = -0.80; P < 0.001). The extracellular volume fraction was higher in IDC patients than in healthy controls (0.31 +/- 0.05 vs. 0.24 +/- 0.03; P = 0.002). Resting MBF was lower in IDC patients (0.64 +/- 0.13 vs. 0.91 +/- 0.22; P = 0.01) than unaffected controls and correlated with both the partition coefficient (r = -0.57; P = 0.012) and the extracellular volume fraction (r = -0.56; P = 0.019). The expansion of the extracellular space correlated with reduced MBF and ventricular dilation. Expansion of the extracellular matrix may be a key contributor to contractile dysfunction in IDC patients.

Late gadolinium enhancement by cardiovascular magnetic resonance heralds an adverse prognosis in nonischemic cardiomyopathy

OBJECTIVES

We examined whether the presence and extent of late gadolinium enhancement (LGE) by cardiovascular magnetic resonance (CMR) predict adverse outcomes in nonischemic cardiomyopathy (NICM) patients.

BACKGROUND

Morbidity and mortality is high in NICM patients. However, the clinical course of an individual patient is unpredictable and current risk stratification approaches are limited. Cardiovascular magnetic resonance detects myocardial fibrosis, which appears as LGE after contrast administration and may convey prognostic importance.

METHODS

In a prospective cohort study, 65 NICM patients with left ventricular (LV) ejection fraction < or =35% underwent CMR before placement of an implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death. The CMR images were analyzed for the presence and extent of LGE and for LV function, volumes, and mass. Patients were followed for an index composite end point of 3 cardiac events: hospitalization for heart failure, appropriate ICD firing, and cardiac death.

RESULTS

A total of 42% (n = 27) of patients had CMR LGE, averaging 10 +/- 13% of LV mass. During a 17-month median follow-up, 44% (n = 12) of patients with LGE had an index composite outcome event versus only 8% (n = 3) of those without LGE (p < 0.001 for Kaplan-Meier survival curves). After adjustment for LV volume index and functional class, patients with LGE had an 8-fold higher risk of experiencing the primary outcome (hazard ratio 8.2, 95% confidence interval 2.2 to 30.9; p = 0.002).

CONCLUSIONS

A CMR LGE in NICM patients strongly predicts adverse cardiac outcomes. The CMR LGE may represent the end-organ consequences of sustained adrenergic activation and adverse LV remodeling, and its identification may significantly improve risk stratification strategies in this high risk population. (Imaging Techniques for Identifying Factors of Sudden Cardiac Death Risk; NCT00181233).

Characterisation of peripartum cardiomyopathy by cardiac magnetic resonance imaging

Peripartum cardiomyopathy (PPCM) is a rare cause of heart failure. Only half of the patients recover normal cardiac function. We assessed the usefulness of magnetic resonance imaging (MRI) and late enhancement imaging to detect myocardial fibrosis in order to predict cardiac function recovery in patients with peripartum cardiomyopathy. Among a consecutive series of 1,037 patients referred for heart failure treatment or prognostic evaluation between 1999 and 2006, eight women had confirmed PPCM. They all underwent echocardiography and cardiac MRI for assessment of left ventricular anatomy, systolic function and detection of myocardial fibrosis through late enhancement imaging. Mean (+/- SD) baseline left ventricular ejection fraction (LVEF) was 28 +/- 4%. After a follow-up of 50 +/- 9 months, half the patients recovered normal cardiac function (LVEF = 58 +/- 4%) and four did not (LVEF = 35 +/- 6%). None of the eight patients exhibited abnormal myocardial late enhancement. No difference in MRI characteristics was observed between the two groups. Patients with PPCM do not exhibit a specific cardiac MRI pattern and particularly no myocardial late enhancement. It suggests that myocardial fibrosis does not play a major role in the limitation of cardiac function recovery after PPCM.

Cardiac assessment of limb-girdle muscular dystrophy 2I patients: an echography, Holter ECG and magnetic resonance imaging study

Mutations in the FKRP gene may be associated with cardiac involvement. The aim of our study was to assess myocardial involvement in patients with LGMD2I, using physical examination, echocardiography, resting and 24-h ambulatory electrocardiogram and cardiac magnetic resonance imaging, with particular attention to the detection of myocardial morphologic abnormalities. Patients were compared to matched controls. Twenty-three patients were enrolled (men 10--women 13; 32.3+/-9.5 years). Twenty-two had the C826A gene mutation (homozygous 12, heterozygous 10). Nine patients had severe muscle alterations, 10 had milder muscle involvement and 4 had isolated exertional myoglobinuria. When compared to controls, LGMD2I patients had reduced left ventricular ejection fraction (50.8+/-13.9 versus 66.6+/-3.8%, p<0.0001). Sixty percent of patients had reduced left ventricular ejection fraction, including 8% with severe reduced left ventricular ejection fraction <30%. None had significant arrhythmia. Gene mutation and the severity of the muscle disease were not predictive of cardiac involvement. Cardiac magnetic resonance imaging displayed a high prevalence of myocardial functional abnormalities, fatty replacement and fibrosis, among the 13 patients investigated. Reduced contractility and cardiac magnetic resonance imaging morphological abnormalities are highly prevalent in LGMD2I patients suggesting that all patients should be referred for cardiac evaluation.

Clinical profile and significance of delayed enhancement in hypertrophic cardiomyopathy

BACKGROUND

Contrast-enhanced cardiovascular magnetic resonance with delayed enhancement (DE) can provide in vivo assessment of myocardial fibrosis. However, the clinical significance of DE in hypertrophic cardiomyopathy (HCM) remains unresolved.

METHODS AND RESULTS

Cine and cardiovascular magnetic resonance with DE were performed in 202 HCM patients (mean age, 42+/-17 years; 71% male), DE was compared with clinical and demographic variables, and patients were followed up for 681+/-249 days for adverse disease events. DE was identified in 111 (55%) HCM patients, occupying 9%+/-11% of left ventricular myocardial volume, including >25% DE in 10% of patients. The presence of DE was related to occurrence of heart failure symptoms (P=0.05) and left ventricular systolic dysfunction (P=0.001). DE was present in all patients with ejection fraction < or =50% but also in 53% (102/192) of patients with preserved ejection fraction (P<0.001); %DE was both inversely related to (r=-0.3; P<0.001) and an independent predictor of ejection fraction (r=-0.4; P<0.001). DE (7%+/-7% of left ventricle) was present in 54 patients who were asymptomatic (and with normal ejection fraction). Over the follow-up period, the annualized adverse cardiovascular event rate in patients with DE exceeded that in patients without DE but did not achieve statistical significance (5.5% versus 3.3%; P=0.5).

CONCLUSIONS

In a large HCM cohort, DE was an independent predictor of systolic dysfunction but with only a modest relationship to heart failure symptoms. These data suggest an important role for myocardial fibrosis in the clinical course of HCM patients but are not sufficient at this time to consider DE as an independent risk factor for adverse prognosis.

A comprehensive approach to management of ventricular arrhythmias

This review presents five cases that highlight the complexity of taking care of patients with ventricular arrhythmias. Three of the cases discuss management of patients with nonsustained ventricular tachycardia in the setting of structural heart disease: dilated cardiomyopathy, hypertrophic cardiomyopathy, and after myocardial infarction. A fourth case asks whether data from implantable cardioverter defibrillator (ICD) trials can be extrapolated to older patients, and the fifth case discusses management of recurrent ventricular arrhythmias in a patient with an ICD.

Occurrence and frequency of arrhythmias in hypertrophic cardiomyopathy in relation to delayed enhancement on cardiovascular magnetic resonance

OBJECTIVES

Our aim was to determine whether myocardial fibrosis, detected by cardiovascular magnetic resonance (CMR), represents an arrhythmogenic substrate in hypertrophic cardiomyopathy (HCM).

BACKGROUND

Myocardial fibrosis is identified frequently in HCM; however, the clinical significance of this finding is uncertain.

METHODS

We studied prevalence and frequency of tachyarrhythmias on 24-h ambulatory Holter electrocardiogram (ECG) with regard to delayed enhancement (DE) on contrast-enhanced CMR in 177 HCM patients (age 41 +/- 16 yrs; 95% asymptomatic or mildly symptomatic).

RESULTS

Premature ventricular contractions (PVCs), couplets, and nonsustained ventricular tachycardia (NSVT) were more common in patients with DE than those without DE (PVCs: 89% vs. 72%; couplets: 40% vs. 17%; NSVT: 28% vs. 4%; p < 0.0001 to 0.007). Patients with DE also had greater numbers of PVCs (202 +/- 655 vs. 116 +/- 435), couplets (1.9 +/- 5 vs. 1.2 +/- 10), and NSVT runs (0.4 +/- 0.8 vs. 0.06 +/- 0.4) than non-DE patients (all p < 0.0001); DE was an independent predictor of NSVT (relative risk 7.3, 95% confidence interval 2.6 to 20.4; p < 0.0001). However, extent (%) of DE was similar in patients with and without PVCs (8.2% vs. 9.1%; p = 0.93), couplets (8.5% vs. 8.4%; p = 0.99), or NSVT (8.3% vs. 8.5%; p = 0.35).

CONCLUSIONS

In this large HCM cohort with no or only mild symptoms, myocardial fibrosis detected by CMR was associated with greater likelihood and increased frequency of ventricular tachyarrhythmias (including NSVT) on ambulatory Holter ECG. Therefore, contrast-enhanced CMR identifies HCM patients with increased susceptibility to ventricular tachyarrhythmias.

Real-time imaging in left atrial mapping and ablation

The catheter-based ablation of atrial fibrillation has been transformed greatly by the introduction of new technologies and techniques. This article describes the major advancements in real-time navigation systems, including both 3D mapping systems and 2D echocardiography. The relative strengths and weakness of these systems and their accuracy on clinical outcome is also discussed. Finally, we explore current and emerging MRI technologies that will allow the assessment of disease progression and enable procedural planning.

Influence of diffuse fibrosis on wave propagation in human ventricular tissue

AIMS

During ageing, after infarction, in cardiomyopathies and other cardiac diseases, the percentage of fibrotic (connective) tissue may increase from 6% up to 10-35%. The presence of increased amounts of connective tissue is strongly correlated with the occurrence of arrhythmias and sudden cardiac death.

METHODS AND RESULTS

In this article, we investigate the role of diffuse fibrosis on wave propagation, arrhythmogenesis, and arrhythmia mechanism in human ventricular tissue using computer modelling. We show that diffuse fibrosis slows down wave propagation and increases tissue vulnerability to wave break and spiral wave formation. We also demonstrate that diffuse fibrosis increases the period of re-entrant arrhythmias and can suppress the restitution-induced transition from tachycardia to fibrillation.

CONCLUSION

The latter suggests that mechanisms different from restitution-induced spiral break-up might be more likely to account for the onset of fibrillation in the presence of large amounts of diffuse fibrotic tissue.

Delayed enhancement cardiac magnetic resonance imaging reveals typical patterns of myocardial injury in patients with various forms of non-ischemic heart disease

BACKGROUND

Late gadolinium-hyperenhancement (LHE) on cardiac magnetic resonance imaging (CMR) has been linked to cardiovascular risk in ischemic and non-ischemic heart disease. We aimed to systematically categorize LHE-patterns in a variety of non-ischemic heart diseases (NIHD) and to explore their relationship with left ventricular (LV) function.

METHODS

In a retrospective database search, 156 patients with NIHD who exhibited LHE on CMR were identified. All images were re-analyzed stepwise. LHE was correlated to LV functional parameters. Cardiac magnetic resonance (CMR) was conducted on 1.5 T scanners.

RESULTS

Typically, LHE spared the subendocardium. Consistent LHE-patterns were observed in myocarditis, hypertrophic and dilated cardiomyopathy and systemic vasculitis. No conclusive LHE-patterns were observed in patients with aortic stenosis, arterial hypertension, lupus erythematosus, sarcoidosis, ventricular arrhythmia and in a mixed subgroup of rare NIHDs. There was no significant relationship between LHE and ejection fraction. There was no correlation between enddiastolic volume and LHE in either myocarditis (P = 0.13) or dilated cardiomyopathy (P = 0.62). LHE was unrelated to LV-mass in aortic stenosis (P = 0.13) and hypertrophic cardiomyopathy (P = 0.38).

CONCLUSIONS

Distinct LHE patterns exist in various NIHDs and their visualization may ultimately aid diagnosis. Unlike in ischemic heart disease, the structure-function relationship does not appear to be strong.

Advances in clinical applications of cardiovascular magnetic resonance imaging

Cardiovascular magnetic resonance (CMR) is an evolving technology with growing indications within the clinical cardiology setting. This review article summarises the current clinical applications of CMR. The focus is on the use of CMR in the diagnosis of coronary artery disease with summaries of validation literature in CMR viability, myocardial perfusion, and dobutamine CMR. Practical uses of CMR in non-coronary diseases are also discussed.

Pattern and distribution of myocardial fibrosis in systemic sclerosis: a delayed enhanced magnetic resonance imaging study

OBJECTIVE

To assess the prevalence and pattern of myocardial fibrosis as detected by delayed enhanced magnetic resonance imaging (DE-MRI) in patients with systemic sclerosis (SSc), and to evaluate a possible association between myocardial fibrosis and cardiac arrhythmias.

METHODS

Forty-one patients with SSc underwent 24-hour Holter monitoring, Doppler echocardiography, and DE-MRI following gadolinium administration.

RESULTS

Technically acceptable DE-MRIs were obtained in 36 patients with SSc. Enhancement on DE-MRI, consistent with myocardial fibrosis, was observed in 24 of these patients (66%), and it was invariably midwall with a linear pattern, mostly involving basal and midcavity segments of the left ventricle. The volume of enhancement (total volume percentage index [TVPI]) did not differ between patients with diffuse SSc and those with limited SSc (mean +/- SD 1.46 +/- 1.73% versus 1.44 +/- 1.77%; P = 0.98). Patients with a long duration (> or = 15 years) of Raynaud's phenomenon had a greater number of enhancing segments (mean +/- SD 6.55 +/- 4.93 versus 2.96 +/- 3.46; P = 0.017) and a greater TVPI (mean +/- SD 2.44 +/- 1.97% versus 1.02 +/- 1.43%; P = 0.02) than those with a duration of Raynaud's phenomenon <15 years. Nineteen patients with SSc (53%) had abnormal Holter study results. Compared with patients with normal Holter study results, those with abnormal results had a greater number of enhancing segments (mean +/- SD 5.4 +/- 4.8 versus 2.5 +/- 2.9; P < 0.05) and a greater TVPI (mean +/- SD 2.1 +/- 1.9% versus 0.8 +/- 1.2%; P < 0.05).

CONCLUSION

DE-MRI can identify myocardial fibrosis in a significant percentage of patients with SSc and may be a useful noninvasive tool for determining cardiac involvement.

Enhanced infarct border zone function and altered mechanical activation predict inducibility of monomorphic ventricular tachycardia in patients with ischemic cardiomyopathy

PURPOSE

To prospectively determine whether mechanical behavior of left ventricular wall segments that contain different degrees of scar tissue and are located at different distances from the interface between infarcted and noninfarcted myocardial tissue can help predict inducibility of monomorphic ventricular tachycardia (VT) in patients with ischemic cardiomyopathy.

MATERIALS AND METHODS

This HIPAA-compliant study was institutional review board approved; written informed consent was obtained from all patients. Forty-six patients (36 men, 10 women; mean age +/- standard deviation, 61.6 years +/- 11.9) with prior myocardial infarction (MI) and left ventricular dysfunction were referred for defibrillator implantation and underwent an electrophysiologic examination and tagged contrast-enhanced magnetic resonance (MR) imaging. Peak circumferential shortening strain (Ecc) and time to peak Ecc were measured in 12 segments from short-axis sections. Remote, adjacent, and border zones were defined according to increasing proximity to the MI. Patients in whom monomorphic VT could be induced (ie, inducible patients) were considered positive for inducibility. Relationships between inducibility of monomorphic VT, peak Ecc, and time to peak Ecc were analyzed with one-way analysis of variance and Bonferroni test.

RESULTS

Inducible patients had more infarcted and border zone sectors and a shorter time to peak Ecc than did noninducible patients in the border zone and adjacent and infarcted regions (P < .001). Peak Ecc in the border zone of inducible patients (-11.42% +/- 0.46 [standard error]) was greater than that in noninducible patients (-10.18% +/- 0.38; P < .05). Ratio of Ecc in border zone and in remote regions was greater (P < .05) in inducible patients than in noninducible patients (1.31 +/- 0.27 vs 0.64 +/- 0.13, respectively).

CONCLUSION

Enhanced border zone function defined as greater Ecc and earlier time to peak Ecc showed positive correlation to VT inducibility in patients with prior MI and left ventricular dysfunction.

[Cardiac MR imaging in arrhythmogenic heart diseases]

INTRODUCTION

Cardiac arrhythmias are assessed with a combination of history, clinical examination, electrocardiogram, Holter monitor, if necessary supplemented by invasive cardiac electrophysiology. In ischemic heart disease (IHD) coronary angiography is performed in addition.

METHODS

Echocardiography is usually the primary imaging modality. MRI is increasingly recognized as an important investigation allowing more accurate cardiac morphological and functional assessment.

RESULTS

Approximately one-fifth of deaths in Western countries are due to sudden cardiac death, 80% of which are caused by arrhythmias. Typical causes range from diseases with high prevalence (IHD in men 30%) to myocarditis (prevalence 1-9%) and rare cardiomyopathies (prevalence HCM 0.2%, ARVC 0.02%, Brugada syndrome approx. 0.5%). The characteristic MRI features of arrhythmogenic diseases and the new aspects of characteristic distribution of late enhancement allow etiologic classification and differential diagnosis.

CONCLUSION

MRI represents an important tool for detection of the underlying cause and for risk stratification in many diseases associated with arrhythmias.

Low-dose carvedilol reduces transmural heterogeneity of ventricular repolarization in congestive heart failure

AIM

To study the effects of carvedilol on the transmural heterogeneity of ventricular repolarization in rabbits with congestive heart failure (CHF).

METHODS

Rabbits were randomly divided into 3 groups: control, CHF and carvedilol treated CHF group. Monophasic action potential duration (MAPD) in the 3 myocardial layers was simultaneously recorded.

RESULTS

All the rabbits in the CHF group had signs of severe CHF. Compared with the control group, the mean blood pressure and cardiac output were significantly decreased, while peripheral resistance was significantly increased in the CHF group. This proved that the CHF model was successful created with adriamycin in this study. Compared to the control group, the ventricular fibrillation threshold (VFT) was remarkably decreased and all MAPD of the 3 myocardial layers were extended in rabbits with CHF. However, the extension of MAPD in the midmyocardium was more obvious. The transmural dispersion of repolarization (TDR) was significantly increased in CHF. Low-dose carvedilol (0.25 mg/kg, twice daily) had no effects on ventricular remodeling. Treatment with low-dose carvedilol significantly increased VFT. Although the MAPD of the 3 myocardial layers were further prolonged in the carvedilol treated CHF group, the prolongation of MAPD in the midmyocardium was shorter than those in the epicardium and endocardium. Treatment with low-dose carvedilol significantly decreased TDR in CHF.

CONCLUSION

In the present study, the transmural heterogeneity of ventricular repolarization increased in the rabbits with CHF. Low-dose carvedilol decreased the transmural heterogeneity of ventricular repolarization in CHF, which may be related to its direct electrophysiological property rather than its effect on ventricular remodeling.

A clinical cardiovascular magnetic resonance service: operational considerations and the basic examination

Cardiovascular magnetic resonance (CMR) is now considered the "gold standard" for the assessment of regional and global systolic function, myocardial infarction and viability, and congenital heart disease. At specialized centers, CMR has become a clinical workhorse for the evaluation of ischemic heart disease and for heart failure and cardiomyopathies. Despite this versatility, general acceptance of CMR in cardiovascular medicine has progressed slowly. This article provides a basic understanding of important operational considerations when starting a CMR service and describes a conceptual framework of the components of a CMR examination.

The Role of Cardiovascular MRI in Heart Failure and the Cardiomyopathies

Heart failure (HF) is a common syndrome related to varied pathophysiologic processes. Individualization of care according to the patient's pathologic and modifiable substrate is of increasing importance. The use of modern cardiovascular MRI (CMR) provides for the centralization of diagnostic testing with the ability to assess cardiac morphology, function, flow, perfusion, acute tissue injury, and fibrosis in a single setting. This offers the potential for a paradigm shift in the noninvasive diagnosis and monitoring of patients with HF. This article outlines a diagnostic approach for the primary use of CMR in the phenotypic characterization, risk stratification, and therapeutic management of patients with HF.