MRI of acute myocarditis: a comprehensive approach based on various imaging sequences

Relation between myocardial edema and myocardial mass during the acute and convalescent phase of myocarditis--a CMR study

BACKGROUND

Myocardial edema is a substantial feature of the inflammatory response in human myocarditis. The relation between myocardial edema and myocardial mass in the course of healing myocarditis has not been systematically investigated. We hypothesised that the resolution of myocardial edema as visualised by T2-weighted cardiovascular magnetic resonance (CMR) is associated with a decrease of myocardial mass in steady state free precession (SSFP)-cine imaging.

METHODS

21 patients with acute myocarditis underwent CMR shortly after onset of symptoms and 1 year later. For visualization of edema, a T2-weighted breath-hold black-blood triple-inversion fast spin echo technique was applied and the ratio of signal intensity of myocardium/skeletal muscle was assessed. Left ventricular (LV) mass, volumes and function were quantified from biplane cine steady state free precession images. 11 healthy volunteers served as a control group for interstudy reproducibility of LV mass.

RESULTS

In patients with myocarditis, a significant decrease in LV mass was observed during follow-up compared to the acute phase (156.7 +/- 30.6 g vs. 140.3 +/- 28.3 g, p < 0.0001). The reduction of LV mass paralleled the normalization of initially increased myocardial signal intensity on T2-weighted images (2.4 +/- 0.4 vs. 1.68 +/- 0.3, p < 0.0001). In controls, the interstudy difference of LV mass was lower than in patients (5.1 +/- 2.9 g vs. 16.3 +/- 14.2 g, p = 0.02) resulting in a lower coefficient of variability (2.1 vs 8.9%, p = 0.04).

CONCLUSION

Reversible abnormalities in T2-weighted CMR are paralleled by a transient increase in left ventricular mass during the course of myocarditis. Myocardial edema may be a common pathway explaining these findings.

Myopericarditis: Etiology, management, and prognosis

Acute pericarditis is often accompanied by some degree of myocarditis. In clinical practice both pericarditis and myocarditis coexist because they share common etiologic agents, mainly cardiotropic viruses. The term "myopericarditis" indicates a primarily "pericarditic syndrome" and it is responsible for the majority of cases. The clinical presentation is varied, reflecting the variability of myocardial involvement, that may be focal or diffuse, affecting any or all cardiac chambers. Probably many cases may be subclinical and subtle cardiac symptoms and signs may be overshadowed by the systemic manifestations of the viral infection. Echocardiography is essential for the diagnosis of left ventricular dysfunction in even subclinical cases and for follow-up of patients with apparently normal left ventricular function. Magnetic resonance imaging holds promise for an effective non-invasive diagnostic tool. Either for acute pericarditis or myopericarditis there is a lack for adequate controlled clinical trials. In myopericarditis the use of NSAID should be cautious, because in animal models of myocarditis, NSAID are not effective and may actually enhance the myocarditic process and increase mortality. In clinical practice lower anti-inflammatory doses are mainly considered to control symptoms. The natural history of myopericarditis in large populations is not known with accuracy. On follow-up, the majority of these cases had objective normalization of echocardiography, electrocardiography, laboratory testing, and functional status, although up to 14% may report atypical, non-limiting chest discomfort. Unfortunately, few data have been published on myopericarditis, the paper reviews current available evidence on the presentation, management, and prognosis of myopericarditis.

Suspected chronic myocarditis at cardiac MR: diagnostic accuracy and association with immunohistologically detected inflammation and viral persistence

PURPOSE

To retrospectively compare the diagnostic accuracy of three cardiac magnetic resonance (MR) imaging approaches for the detection of histologic and immunohistologic criteria (reference standard) proved myocardial inflammation in patients clinically suspected of having chronic myocarditis (CMC).

MATERIALS AND METHODS

Cardiac MR imaging was performed in 83 consecutive patients (55 male, 28 female; mean age, 44.8 years +/- 17.7 [standard deviation]) clinically suspected of having CMC, after written informed consent was obtained according to guidelines of the local ethics committee, which approved the study. T2-weighted triple-inversion-recovery imaging to calculate the edema ratio (ER), T1-weighted imaging before and after contrast agent administration to calculate the myocardial global relative enhancement (gRE), and inversion-recovery gradient-echo imaging to evaluate areas of late gadolinium enhancement (LE) were performed. The MR results were correlated with the endomyocardial biopsy (EMB) findings to detect intramyocardial inflammation and cardiotropic viral genomes analyzed at polymerase chain reaction assay. For statistical analyses, receiver operating characteristic analysis and the Wilcoxon test for unpaired data were used because the Kolomogorov-Smirnov test revealed a distribution of data that was different from normality.

RESULTS

Intramyocardial inflammation and cardiotropic viral persistence were confirmed at immunohistologic analysis in 48 and 49 of the 83 patients, respectively. The sensitivity, specificity, and diagnostic accuracy of the MR parameters, as compared with the immunohistologic detection of inflammation, were, respectively, 62%, 86%, and 72% for gRE; 67%, 69%, and 68% for ER; and 27%, 80%, and 49% for LE. Cardiac MR-derived gRE, ER, and LE were not associated with polymerase chain reaction proof of viral genomes.

CONCLUSION

In patients clinically suspected of having CMC, increased gRE and ER indicating inflammation were common findings that could be confirmed at immunohistologic analysis, whereas LE had low sensitivity and accuracy. Cardiac MR imaging may be helpful in detecting intramyocardial inflammation noninvasively, but it fails to depict viral persistence.

Acute myopericarditis after multiple vaccinations in an adolescent: case report and review of the literature

We report a case of postvaccination acute myopericarditis in an adolescent. The patient presented with acute chest pain, diffuse ST-segment elevation, and elevated cardiac enzyme levels. Cardiac MRI was consistent with acute myocarditis. He recovered within a few days with nonsteroidal antiinflammatory treatment and remains clinically stable, with improvement of MRI findings at the 10-week follow-up. Postvaccination cases of myopericarditis reported in the pediatric literature are also reviewed.

Viral myocarditis masquerading acute coronary syndrome (ACS)--MRI to the rescue

A young man with a strong family history of myocardial infarction with sudden death presented with chest pain and was found to have positive cardiac biomarkers and echocardiographic evidence of inferolateral wall hypokinesia. He was managed as an acute coronary syndrome and underwent a thorough ischemic work-up which was negative. Subsequently, a cardiac MRI was performed that demonstrated a patchy subepicardial enhancement, most consistent with acute viral myocarditis. This case demonstrates the importance of cardiac MRI in distinguishing an acute coronary syndrome from viral myocarditis.

Value of MRI in patients with a clinical suspicion of acute myocarditis

The diagnosis of myocarditis is difficult and is generally one of exclusion. Moreover, endomyocardial biopsy (EMB) is not a sensitive technique. Magnetic resonance imaging (MRI), however, has shown promising results in diagnosing myocarditis. We evaluated 20 patients with a clinical suspicion of acute myocarditis. Troponin I levels were elevated in 17/20 patients. Cardiac catheterization (n = 13) showed no evidence of coronary artery disease, while normal findings were reported in all five patients who underwent EMB. MRI performed 9.8 +/- 7.5 days after the onset of symptoms showed an LV-EDV of 172 +/- 50 ml and LV-EF of 57 +/- 10%. Abnormalities on delayed contrast-enhanced MRI were found in 15/20 patients, involving 3.7 +/- 2.1 segments using the 17-segment model. The lateral LV wall was most frequently involved (61% of enhanced segments). The enhancement was most frequently subepicardial, less often transmural, or midwall (respectively, 67%, 22%, and 11% of enhanced segments). Mild to moderate systolic wall motion abnormalities were invariably found in the abnormally enhancing myocardium on MRI. Associated pericardial effusion was found in six, pericardial enhancement in nine patients. In conclusion, the present study suggests an important role for MRI in evaluating patients with clinical suspicion of acute myocarditis. Not only can the myocardial damage be precisely depicted but also concomitant involvement of the pericardium and impact on regional and global ventricular function can be assessed.

Comparison of delayed myocardial enhancement in the early and late phase after contrast injection: is it possible to reduce the examination time for myocardial viability study?

OBJECTIVES

We studied whether we can obtain a myocardial viability study immediately after contrast injection to reduce the whole cardiac MR examination time.

MATERIALS AND METHODS

We examined 36 patients with cardiovascular abnormality on comprehensive cardiac MRI. T1-weighted images with inversion recovery (IR) were obtained 5 min after stress perfusion with 0.05 mmol/kg of gadodiamide and 15 min after the resting perfusion with the same dose. (The latter images were obtained 25 min after the initial administration.) We evaluated the existence, the number of sectors, and the degree of enhancement at each time. The contrast ratio was also calculated. The number of the enhanced sectors and the contrast ratio were statistically compared using Student's t test.

RESULTS

All 17 cases of delayed myocardial enhancement at 25 min after contrast injection showed some enhancement at 5 min after contrast injection. However, the number of enhanced sectors was larger at 25 min after the initial injection in 11 cases, and it was statistically significant (P=.017). The degree of enhancement was stronger at 25 min in 14 cases. However, the contrast ratio at 5 and 25 min after contrast injection was not significantly different (P=.245).

CONCLUSION

Myocardial viability study immediately after contrast injection is too early to evaluate the extent of myocardial injury.

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.

Noninvasive imaging in myocarditis

Increased recognition of the role of inflammation in acute and chronic dilated cardiomyopathy has revived an interest in noninvasive imaging for detection of myocarditis. Diagnostic strategies that are based on molecular imaging promise to further advance our understanding and improve diagnostic precision. This article reviews the strengths and limitations of common clinical tests used for the diagnosis of myocarditis, with a focus on the emerging role of cardiovascular magnetic resonance imaging. Novel imaging modalities that are currently in preclinical development are discussed with recommendations for future clinical research.

Diagnostic value of ECG-gated multidetector computed tomography in the early phase of suspected acute myocarditis. A preliminary comparative study with cardiac MRI

The aim of the study was to determine the potential diagnostic value of contrast-enhanced echocardiogram (ECG)-gated multidetector computed tomography (MDCT) in the setting of suspected acute myocarditis compared with contrast-enhanced magnetic resonance imaging (MRI). The study group consisted of 12 consecutive patients admitted for suspected acute myocarditis less than 10 days after onset of symptoms. All patients had clinical, electrocardiographic signs, and laboratory findings consistent with the diagnosis. All patients but one (severe claustrophobia) underwent cardiac MRI using T1-weighted delayed-enhancement images after injection of gadolinium. ECG-gated MDCT was performed in all patients and included a first-pass contrast-enhanced acquisition and a delayed acquisition. MRI revealed abnormal focal or multifocal myocardial enhancement and confirmed the diagnosis in 11 patients. The first-pass MDCT acquisition showed homogenous left-ventricle contrast enhancement and absence of coronary stenosis in all patients. Delayed MDCT acquisition, performed 5 min later without reinjection of contrast medium revealed multiple areas of myocardial hyperenhancement in a focal or a multifocal pattern (six and six patients, respectively). Extent and location of hyperenhancement at MDCT correlated well with that observed at MR examination for all 11 patients evaluated by both techniques (r=0.9167, p=0.0004). These preliminary results show that ECG-gated MDCT could be a useful alternative noninvasive diagnostic test in the early phase of acute myocarditis.

A Case of Acute Myocarditis with Evaluation of Magnetic Resonance Imaging

A 42-year-old male with acute chest pain referred for acute myocarditis versus myocardial infarction (MI) was examined with magnetic resonance imaging (MRI). Clinical presentation and MRI findings are reviewed.

MR findings in cardiac amyloidosis

OBJECTIVE

The objective of our study was to describe a combination of features on MRI specific to cardiac amyloidosis.

CONCLUSION

Cardiac amyloidosis is a common cause of infiltrative heart disease. The combination of subtle widespread heterogeneous myocardial enhancement on delayed postcontrast inversion recovery T1-weighted images, which may initially be dismissed as a technical error, with ancillary features of restrictive cardiac disease is highly suggestive of cardiac amyloidosis.

[Myocarditis versus myocardial infarction in diabetic patients: a new role for non invasive imaging]

A young diabetic patient was referred to our institution for clinical symptoms of myopericarditis. Cardiac MRI and MDCT of the coronary arteries were performed successively. They demonstrated an acute myocardial infarction related to a left circumflex coronary artery occlusion which was treated by stent angioplasty. This case suggests that cardiac MR and possibly cardiac MDCT could be proposed in patients with a suspected myopericarditis, especially if diabetes mellitus is associated.

Survival in biopsy-proven myocarditis: a long-term retrospective analysis of the histopathologic, clinical, and hemodynamic predictors

OBJECTIVE

We hypothesized that histopathology predicts survival without cardiac transplantation in patients with biopsy-proven myocarditis.

BACKGROUND

The role of endomyocardial biopsy in diagnosing myocarditis remains controversial. Histopathology has been integrated with clinical and hemodynamic features to predict prognosis. However, the influence of histopathology on survival > 5 years has not been explored.

METHODS

We retrospectively identified 112 consecutive patients with histopathologic confirmation of myocarditis. We examined these patients' clinical presentation, hemodynamic assessment, hospital course, and treatment. We selected 14 variables that might influence survival without cardiac transplantation.

RESULTS

A total of 62 (55%) of 112 patients had lymphocytic myocarditis; 88 (79%) and 63 (56%) were alive without cardiac transplantation at 1 and 5 years, respectively. Median follow-up was a mean 95.5 months and median 74.5 months. Among the 55 with complete data of the 14 candidate predictor variables, age, sex, and clinical presentation with congestive heart failure and ventricular (ventricular tachycardia or fibrillation) or atrial arrhythmias (atrial fibrillation or flutter) did not predict the study end point of death or need for transplantation. In univariate analysis, pulmonary capillary wedge pressure > or = 15 mm Hg significantly predicted the study end point. In multivariate analysis, pulmonary capillary wedge pressure > or = 15 mm Hg and histopathology of lymphocytic, granulomatous, or giant cell myocarditis each significantly predicted mortality or transplant (P = .047, P = .013, and P = .054, respectively) on cumulative survival without cardiac transplantation.

CONCLUSIONS

Histopathology predicts long-term survival in patients with myocarditis. Clinical presentation, including presentation with congestive heart failure, ventricular tachycardia/ventricular fibrillation, or atrial fibrillation/atrial flutter, does not predict survival without transplantation. Endomyocardial biopsy can play a role in predicting transplant-free survival in patients with myocarditis.

Human myocardium: single-breath-hold MR T1 mapping with high spatial resolution--reproducibility study

A prospective study approved by the local ethics committee was performed to establish the normal range and reproducibility of myocardial T1 values as assessed with single-breath-hold T1 mapping with high spatial resolution. With a 1.5-T magnetic resonance (MR) imaging system, baseline and contrast material-enhanced modified Look-Locker inversion recovery, or MOLLI, imaging was performed in 15 healthy volunteers who had given written informed consent. Image quality scores and myocardial T1 values were derived for standard short-axis segments and sections. Results were compared with those from a second MR imaging study performed on the same day (baseline only) and those from a third study performed on a different day (baseline and contrast enhanced; eight volunteers). Intra- and interobserver agreement were determined. Myocardial T1 maps were obtained rapidly in a reproducible fashion. A normal range for baseline and postcontrast myocardial T1 was established (baseline mean T1 in short-axis sections, 980 msec +/- 53 [standard deviation]; 95% confidence interval: 964, 997; number of sections, 43). This technique could enable direct quantification of changes in tissue characteristics in ischemic and inflammatory myocardial diseases.

Efficacy of spectral presaturation of inversion recovery in evaluating delayed myocardial enhancement

OBJECTIVE

Delayed myocardial enhancement is caused by a variety of cardiovascular diseases. The extent of the enhanced area has been examined by the inversion recovery (IR) method, whereby at the inversion time (TI), normal myocardium shows a low signal intensity. In this sequence, as pericardial fat shows a very high intensity, a delayed enhancement just below the pericardium may be indistinct. To improve the accuracy of delayed myocardial enhancement, we employed the spectral presaturation of inversion recovery (SPIR) method.

MATERIALS AND METHODS

Thirty-five patients with symptoms of cardiovascular disease aged between 36 and 80 years old (mean age, 62 years old) were investigated. Thirty were men and five were women. Inversion recovery and SPIR images were obtained 25 min after initial administration of a gadolinium-based contrast material. Each TI, when the signal intensity of the normal myocardium was null, was determined by images obtained at serial different TIs. A radiologist and a cardiologist examined each image by a consensus reading. The extent of myocardial enhancement was described as none, subendocardial, transmural and a random pattern in each case. Images were ranked over three levels and were based on whether myocardial enhancement could be easily detected or whether the contour of the myocardium was visualized precisely. Student's t-test was conducted to compare the quality of two sequences in all patients and in 22 patients who showed delayed myocardial enhancement.

RESULTS

The imaging quality in evaluating delayed myocardial enhancement in all patients was superior with IR compared with SPIR, although it was not statistically significant. The imaging quality in the patients with delayed myocardial enhancement was similar between SPIR and IR. SPIR was superior to the IR sequence in two of the four patients who exhibited transmural enhancement.

CONCLUSION

SPIR exhibited equivalent image quality to IR in evaluating delayed myocardial enhancement. As it has the potential advantage in patients with rich adipose tissue surrounding the myocardium, it can be an alternative sequence to evaluate myocardial viability.

Differentiating acute myocardial infarction from myocarditis: diagnostic value of early- and delayed-perfusion cardiac MR imaging

PURPOSE

To prospectively determine whether early first-pass perfusion and delayed-enhancement magnetic resonance (MR) imaging sequences can enable differentiation of acute myocardial infarction (AMI) from myocarditis in patients with acute chest pain.

MATERIALS AND METHODS

All examinations were performed according to guidelines of the institutional board on medical ethics and clinical investigation and after informed patient consent was obtained. Fifty-five patients with a clinical presentation suggestive but not typical of AMI were examined. At final diagnosis, 31 patients had AMI and 24 had myocarditis. At-rest MR imaging was performed and included first-pass perfusion and delayed-enhancement sequences. Three independent observers read each image data set separately and then in consensus. The main abnormalities included first-pass perfusion defects and delayed highly enhancing areas. The numbers and distributions of involved segments and the transmural extents and the shapes of the highly enhancing areas were noted. For comparisons between the AMI and myocarditis patient groups, the chi2 test was used to assess the locations of the abnormalities and the Mann-Whitney U test was used to assess the numbers of involved segments. The final diagnoses were obtained with coronary angiography as the reference standard for the AMI group and on the basis of normal coronary angiographic findings and the spontaneous resolution of clinical symptoms and wall motion abnormalities for the myocarditis group.

RESULTS

MR imaging patterns were significantly different between the two cardiac disease groups (P < .05). All the patients with AMI had a segmental early subendocardial defect, with corresponding segmental subendocardial or transmural delayed high enhancement in a predominantly anteroseptal or inferior vascular distribution in 28 patients. All patients with AMI had stenosis of at least the infarct-affected coronary artery. All but one of the patients with myocarditis had no early defect and focal or diffuse nonsegmental nonsubendocardial delayed enhancement predominantly in an inferolateral location.

CONCLUSION

Use of combined early- and late-perfusion MR imaging sequences helps to distinguish AMI from myocarditis.

Diagnostic performance of cardiovascular magnetic resonance in patients with suspected acute myocarditis: comparison of different approaches

OBJECTIVES

The aim of this research was to identify the diagnostic performance of gadolinium-enhanced and T2-weighted cardiovascular magnetic resonance (CMR) in suspected acute myocarditis.

BACKGROUND

Acute myocarditis is difficult to diagnose; CMR provides various means to visualize myocardial inflammatory changes. A CMR approach with clear-cut diagnostic criteria would be desirable.

METHODS

We investigated 25 patients with suspected acute myocarditis (18 males, 44 +/- 17 years) and 23 healthy controls (13 males, 29 +/- 10 years). Cardiovascular magnetic resonance studies included the following sequences: 1) T2-weighted triple inversion recovery; 2) T1-weighted spin echo before and over 4 min after gadolinium injection; and 3) inversion recovery-gradient echo 10 min after gadolinium injection. Qualitative and quantitative image analysis was performed for: 1) focal and global T2 signal intensity (SI); 2) myocardial global relative enhancement (gRE); and 3) areas of late gadolinium enhancement (LGE).

RESULTS

Both global T2 SI and gRE were higher in patients than in controls (T2: 2.3 +/- 0.4 vs. 1.7 +/- 0.4; p < 0.0001, gRE: 6.8 +/- 4.0 vs. 3.7 +/- 2.3; p < 0.001). The sensitivity, specificity, and diagnostic accuracy for T2 (cutoff value of 1.9) were 84%, 74%, and 79%, respectively; gRE: (cutoff value of 4.0) 80%, 68%, and 74.5% respectively; LGE: 44%, 100%, and 71%, respectively. The best diagnostic performance was obtained when "any-two" of the three sequences were positive in the same patient yielding a 76% sensitivity, 95.5% specificity, and 85% diagnostic accuracy.

CONCLUSIONS

A combined CMR approach using T2-weighted imaging, early and late gadolinium enhancement, provides a high diagnostic accuracy and is a useful tool in the diagnosis and assessment of patients with suspected acute myocarditis.

Contrast enhanced-cardiovascular magnetic resonance imaging in patients with pulmonary hypertension

AIMS

To determine the presence and extent of delayed contrast enhancement (DCE) in patients with pulmonary hypertension (PHT) using contrast enhanced-cardiovascular magnetic resonance imaging (ce-CMR).

METHODS AND RESULTS

Twenty-five patients with PHT underwent ce-CMR and right heart catheterization. Right ventricular (RV) and left ventricular (LV) volumes, ejection fraction, mass, and DCE mass were determined with ce-CMR. Mean pulmonary artery pressure (mean PAP) averaged 43 (12) mmHg and cardiac output 4.3 (1.2) L/min. DCE was demonstrated in 23 out of 25 patients. DCE was confined to the RV insertion points (RVIPs) in seven patients and extended into the interventricular septum (IVS) in the remaining 16 patients. In these 16 patients, septal contrast enhancement was associated with IVS bowing. The extent of contrast enhancement correlated positively with RV end-diastolic volume/body surface area, RV mass, mean PAP, and pulmonary vascular resistance and correlated inversely with RV ejection fraction.

CONCLUSION

DCE was present within the RVIPs and IVS of most patients with PHT studied. Extent of DCE correlated with RV function and pulmonary haemodynamics. DCE was associated with IVS bowing and may provide a novel marker for occult septal abnormalities directly relating to the haemodynamic stress experienced by these patients.

Localisation myocardique de la tuberculose

INTRODUCTION

Tuberculosis can be responsible for myocardial damage, the frequency of which is probably underestimated because of the difficulty in its diagnosis. We studied the contribution of cardiac magnetic resonance imaging (MRI) in three patients.

OBSERVATIONS

Three patients were treated for disseminated tuberculosis. They had moderate cardiac abnormalities (tachycardia, dyspnoea on effort). The electrocardiogram was normal in 2 patients and the echocardiography showed localized hyperkinesias. Cardiac MRI revealed intra-myocardial nodular gadolinium enhancement and hyperkinesias. The clinical outcome in the 3 patients was favourable following anti-tuberculosis therapy; one patient was also administered corticosteroids.

DISCUSSION

Cardiac MRI is a non-invasive examination that brought important arguments for the diagnosis of tubercular myocarditis in the 3 patients.

Contrast-enhanced MR imaging of the heart: overview of the literature

The use of magnetic resonance (MR) imaging for cardiac diagnosis is expanding, aided by the administration of paramagnetic contrast agents for a growing number of clinical applications. This overview of the literature considers the principles and applications of cardiac MR imaging with an emphasis on the use of contrast media. Clinical applications of contrast material-enhanced MR imaging include the detection and characterization of intracardiac masses, thrombi, myocarditis, and sarcoidosis. Suspected myocardial ischemia and infarction, respectively, are diagnosed by using dynamic first-pass and delayed contrast enhancement. Promising new developments include blood pool contrast media, labeling of myocardial precursor cells, and contrast-enhanced imaging at very high fields.

Histologic findings in patients with clinical and instrumental diagnosis of sporadic arrhythmogenic right ventricular dysplasia

OBJECTIVES

We sought to analyze the histologic findings of 30 patients with a diagnosis of arrhythmogenic right ventricular dysplasia (ARVD) based on established clinical and instrumental criteria, who did not have a family history of ARVD.

BACKGROUND

The diagnostic role of endomyocardial biopsy (EMB) in patients with a clinical profile of ARVD is still debated.

METHODS

Thirty patients (19 male, 11 female, mean age 27 +/- 10 years) with left bundle branch block morphology ventricular tachyarrhythmias and echocardiographic, angiographic, and magnetic resonance imaging (MRI) findings diagnostic of ARVD were studied. All patients, besides diagnostic, noninvasive, and invasive cardiac studies, underwent EMB in the apex, anterior free wall, inferior wall of the right ventricle (RV) and in the septal-apical region of the left ventricle.

RESULTS

Diagnostic histologic features of ARVD were found only in 9 (30%) patients and a myocarditis, according to the Dallas criteria, in the remaining 21 (70%) patients. Morphometric evaluation of RV samples showed significant differences in fatty tissue and myocyte percent area between ARVD and myocarditis (p < 0.001). Conversely, no difference was found between the two groups in arrhythmic patterns and structural and functional echocardiographic, angiographic, and MRI RV alterations. Magnetic resonance imaging showed hyperintense signals in 67% of ARVD and in 62% of myocarditis group (p = NS). During follow-up (mean, 23 +/- 14 months), all patients with myocarditis remained stable on antiarrhythmic therapy while five patients with ARVD required implantation of an implantable cardioverter defibrillator.

CONCLUSIONS

A myocarditis involving the RV can mimic ARVD. An EMB appears the most reliable diagnostic technique, with significant prognostic and therapeutic implications.

Role of MRI in clinical cardiology

Rapid progress has been made in cardiac MRI (CMRI) over the past decade, which has firmly established it as a reliable and clinically important technique for assessment of cardiac structure, function, perfusion, and myocardial viability. Its versatility and accuracy is unmatched by any other individual imaging modality. CMRI is non-invasive and has high spatial resolution and avoids use of potentially nephrotoxic contrast agent or radiation. It has been extensively studied against other established non-invasive imaging modalities and has been shown to be superior in many scenarios, particularly with respect to assessment of cardiac and great vessel morphology and left ventricular function. Furthermore, its clinical use continues to expand with increasing experience and proliferation of CMRI centres. As worldwide prevalence of cardiovascular disease continues to rise, CMRI provides opportunity for improved and cost-effective non-invasive assessment. Continued progress in CMRI technology promises to further widen its clinical application in coronary imaging, myocardial perfusion, comprehensive assessment of valves, and plaque characterisation.

MR imaging in ischemic heart disease

This article reviews the current MR imaging literature with respect to ischemic heart disease and focuses on the clinical practicalities of cardiac MR imaging today.

[Cardiomyopathies]

Cardiomyopathies include a wide variety of cardiac diseases. The value of MR imaging is not only to provide information about cardiac function, but also to detect the underlying cause of the disease.

Smallpox vaccination and myopericarditis: a clinical review

Smallpox is a devastating viral illness that was eradicated after an aggressive, widespread vaccination campaign. Routine U.S. childhood vaccinations ended in 1972, and routine military vaccinations ended in 1990. Recently, the threat of bioterrorist use of smallpox has revived the need for vaccination. Over 450,000 U.S. military personnel received the vaccination between December 2002 and June 2003, with rates of non-cardiac complications at or below historical levels. The rate of cardiac complications, however, has been higher than expected, with two confirmed cases and over 50 probable cases of myopericarditis after vaccination reported to the Department of Defense Smallpox Vaccination Program. The practicing physician should use the history and physical, electrocardiogram, and cardiac biomarkers in the initial evaluation of a post-vaccination patient with chest pain. Echocardiogram, cardiac catheterization, magnetic resonance imaging, nuclear imaging, and cardiac biopsy may be of use in further workup. Treatment is with non-steroidal anti-inflammatory agents, four to six weeks of limited exertion, and conventional heart failure treatment as necessary. Immune suppressant therapy with steroids may be uniquely beneficial in myopericarditis related to smallpox vaccination, compared with other types of myopericarditis. If a widespread vaccination program is undertaken in the future, many more cases of post-vaccinial myopericarditis could be seen. Practicing physicians should be aware that smallpox vaccine-associated myopericarditis is a real entity, and symptoms after vaccination should be appropriately evaluated, treated if necessary, and reported to the Vaccine Adverse Events Reporting System.

Coronary plaque burden detected by multislice computed tomography after acute myocardial infarction with near-normal coronary arteries by angiography

Nonsignificant coronary artery plaque rupture or erosion may be the origin of acute myocardial infarction (AMI). The aim of our study was to assess the ability of multislice computed tomography (MSCT) to detect coronary plaques responsible for near normal coronary angiography AMI. Eight patients with presentation of AMI and no significant coronary narrowing by angiography were enrolled. Two groups were defined: (1) true AMI and (2) myocarditis. MSCT was able to detect nonsignificant coronary soft plaques responsible for AMI and has provided information on plaque volume, eccentricity, and density. In patients with myocarditis, there was no evidence of plaque.

Contrast-enhanced cardiovascular magnetic resonance imaging

Since its introduction in the early 1990s, contrast-enhanced (CE) cardiac magnetic resonance imaging (MRI) has evolved rapidly for the assessment of cardiac pathologies, including in particular ischemic heart disease and inflammatory conditions. Likewise, CE-magnetic resonance angiography (MRA) is now used routinely to evaluate the thoracic vasculature. This article reviews the current use of extracellular gadolinium-based agents in CE cardiovascular imaging, focusing on ischemic heart disease, inflammatory myocardial conditions, and the use of CE-MRA in imaging of the pulmonary and aortic vasculature. Recent advances in fast and ultrafast MRI combined with the use of extracellular contrast media allow noninvasive measurements of multiple parameters of the cardiovascular system in less than 40 minutes. Beyond the assessment of left ventricular wall motion and morphology, CE cardiac MRI allows depiction of myocardial perfusion and thereby provides information regarding microvascular integrity and myocardial viability. The excellent spatial resolution of MRI, especially for the distinction of nontransmural versus transmural extent of pathology, has been shown to be superior to other modalities that are often nonlocalizing, nonspecific, or more invasive. Additional advantages of CE-MRA, particularly for the thoracic vasculature, include safety, its noninvasive character, large field of view, and the ability to demonstrate complicated three-dimensional relationships without the need for iodinated, nephrotoxic contrast media.

Measurement of the RT interval on ECG records during electron-beam CT

RATIONALE AND OBJECTIVES

The R wave of the electrocardiogram is used widely as a trigger for cardiac imaging. This study was designed to determine the optimal interval between the R wave and end systole for triggering of electron-beam computed tomography (CT) in a group of patients with various heart rates who are undergoing assessment for coronary artery calcification.

MATERIALS AND METHODS

A total of 862 consecutive asymptomatic patients referred for screening with electron-beam CT for coronary artery calcification were enrolled in the study. Patients' R-R, RT, and PR intervals were measured by using the software of the CT console computer. Correlation coefficients were computed and linear regression analyses were performed for all intervals measured. Results were analyzed according to patient age (three subgroups), sex (two subgroups), and heart rate (nine subgroups). Separate formulas for calculating the length of RT intervals in men and in women were developed.

RESULTS

After correction for heart rate, a significant difference was found in mean RT and PR intervals between women and men, with the mean intervals in women being longer (P < .001). No significant difference was found in these intervals within the three age-defined subgroups (< or = 40, 41-60, and >60 years; P > .05). However, significant negative correlations were found between heart rates and the lengths of all measured intervals. The results of statistical analysis indicate that most of the variation in the R-R interval with different heart rates occurred in diastole and that the duration of systole was relatively constant.

CONCLUSION

For optimal cardiac imaging, triggering should take place in late systole, avoiding the RT interval variability that occurs in diastole.