Special investigations of COCM: endomyocardial biopsies (morphological analysis)

Current Insights and Novel Cardiovascular Magnetic Resonance-Based Techniques in the Prognosis of Non-Ischemic Dilated Cardiomyopathy

Cardiac magnetic resonance (CMR) imaging has an important emerging role in the evaluation and management of patients with cardiomyopathies, especially in patients with dilated cardiomyopathy (DCM). It allows a non-invasive characterization of myocardial tissue, thus assisting early diagnosis and precise phenotyping of the different cardiomyopathies, which is an essential step for early and individualized treatment of patients. Using imaging techniques such as late gadolinium enhancement (LGE), standard and advanced quantification as well as quantitative mapping parameters, CMR-based tissue characterization is useful in the differential diagnosis of DCM and risk stratification. The purpose of this article is to review the utility of CMR in the diagnosis and management of idiopathic DCM, as well as risk prediction and prognosis based on standard and emerging CMR contrast and non-contrast techniques. This is consistent with current evidence and guidance moving beyond traditional prognostic markers such as ejection fraction.

Right ventricular dysfunction, late gadolinium enhancement, and female gender predict poor outcome in patients with dilated cardiomyopathy

AIMS

Dilated cardiomyopathy (DCM) shows a variable disease course and is associated with significant morbidity and mortality. So far, left ventricular function (LVF) is the major determinant for risk stratification. However, since it has shown to be a poor guide to individual outcome, we studied the prognostic value of cardiovascular magnetic resonance imaging (CMR) parameters, late gadolinium enhancement (LGE) and epicardial adipose tissue (EAT).

METHODS AND RESULTS

140 patients with DCM underwent late gadolinium enhancement (LGE) CMR. During a median follow-up of 3 years, 22 patients (16%) died and another 51 (36%) were hospitalized due to congestive heart failure (CHF). Female gender and right ventricular ejection fraction (RV-EF) below the median of 38% were independent predictors of all-cause mortality in multivariable analysis. In patients who were hospitalized due to CHF, RV-EF below the median of 38% was the only independent predictor in multivariable analysis. When patients where further stratified according to systolic LV-EF, the prognostic value of RV-EF to predict mortality and cardiac morbidity remained unchanged. Looking at DCM patients who died during follow-up compared to those who were hospitalized due to CHF, the former presented with a higher prevalence of LGE as well as reduced indexed EAT.

CONCLUSION

Female gender, RV-EF and the presence of LGE are of prognostic importance in patients with DCM. Therefore, the present study underlines the role of CMR as an important tool for risk stratification in patients with DCM.

Differences in antiapoptotic, proliferative activities and morphometry in dilated and ischemic cardiomyopathy: study of hearts explanted from transplant recipients

BACKGROUND

Antiapoptotic as well as replacement and proliferative mechanisms take place in the myocardium in dilated cardiomyopathy (DCM) and ischemic heart disease (IHD). We sought to estimate antiapoptotic, proliferative and replacement activities in cardiomyopathies.

MATERIALS

The study groups included seven hearts with DCM and eight with IHD, which had been explanted at the time of transplantation. The comparator group consisted of cases of myocardial hypertrophy and the control group, donor fragments.

METHODS

Antiapoptotic and proliferative responses were determined immunohistochemically as Bcl-2 and Ki67 expression by semiquantitative assessment of the intensity of staining. We also measured and statistically analyzed the integrative morphometric measurements of the fraction of fibrosis area, the nucleosarcoplasmic ratio, and cardiocyte diameter.

RESULTS

No Bcl-2 expression was observed in the controls. The strongest reaction was seen in the DCM group, then in the IHD, and in the comparator group of myocardial hypertrophy. Proliferative activity was seen only in endocardial and interstitial fibroblasts in DCM and IHD cases. The cardiocyte diameter showed no statistical association between myocardial hypertrophy and IHD, or IHD and DCM, whereas the nucleosarcoplasmic ratios were significantly different from control groups for all comparisons. Myocardial fibrosis showed the highest values in DCM and IHD. Discriminant analysis showed the value of interstitial fibrosis and cardiocyte diameter to categorize the analyzed groups.

CONCLUSIONS

Antiapoptotic Bcl-2 activity seemed to play an important role in cardiocyte preservation, while proliferative activity was resticted to interstitial connective tissue cells as a replacement process. Myocardial Bcl-2 expression, the extent of myocardial fibrosis, and cardiocyte diameter may serve as additional diagnostic tools to differentiate cardiomyopathies.

Angiotensin-converting enzyme (ACE) inhibitors revert abnormal right ventricular filling in patients with restrictive left ventricular disease

OBJECTIVES

Our aim was to determine mechanisms underlying abnormalities of right ventricular (RV) diastolic function seen in heart failure.

BACKGROUND

It is not clear whether these right-sided abnormalities are due to primary RV disease or are secondary to restrictive physiology on the left side of the heart. The latter regresses with angiotensin-converting enzyme inhibition (ACE-I).

METHODS

Transthoracic echo-Doppler measurements of left- and right-ventricular function in 17 patients with systolic left ventricular (LV) disease and restrictive filling before and 3 weeks after the institution of ACE-I were compared with those in 21 controls.

RESULTS

Before ACE-I, LV filling was restrictive, with isovolumic relaxation time short and transmitral E wave acceleration and deceleration rates increased (p < 0.001). Right ventricular long axis amplitude and rates of change were all reduced (p < 0.001), the onset of transtricuspid Doppler was delayed by 160 ms after the pulmonary second sound versus 40 ms in normals (p < 0.001) and overall RV filling time reduced to 59% of total diastole. Right ventricular relaxation was very incoordinate and peak E wave velocity was reduced. Peak RV to right atrial (RA) pressure drop, estimated from tricuspid regurgitation, was 45+/-6 mm Hg, and peak pulmonary stroke distance was 40% lower than normal (p < 0.001). With ACE-I, LV isovolumic relaxation time lengthened, E wave acceleration and deceleration rates decreased and RV to RA pressure drop fell to 30+/-5 mm Hg (p < 0.001) versus pre-ACE-I. Right ventricular long axis dynamics did not change, but tricuspid flow started 85 ms earlier to occupy 85% of total diastole; E wave amplitude increased but acceleration and deceleration rates were unaltered. Values of long axis systolic and diastolic measurements did not change. Peak pulmonary artery velocity increased (p < 0.01).

CONCLUSIONS

Abnormalities of RV filling in patients with heart failure normalize with ACE-I as restrictive filling regresses on the left. This was not due to altered right ventricular relaxation or to a fall in pulmonary artery pressure or tricuspid pressure gradient, but appears to reflect direct ventricular interaction during early diastole.

Left ventricular function and endomyocardial biopsy in early and advanced dilated cardiomyopathy

We evaluated left ventricular function and endomyocardial biopsy in 20 patients with early and advanced dilated cardiomyopathy, with the purpose of assessing the correlation between histologic variables and systolic and diastolic filling indexes. Group 1 included 10 patients with no clinical history of heart failure and left ventricular ejection fraction > or = 45% and group 2, 10 patients with a clinical history of heart failure and left ventricular ejection fraction <45%. Group 1 showed lower left ventricular end-systolic and end-diastolic volumes indexes (49+/-14 versus 86+/-23 ml/m2, P<0.001; 98+/-25 versus 127+/-35 ml/m2, P=0.049), higher left ventricular ejection fraction (50+/-4 versus 32+/-4%, P<0.001) and lower coefficient of variation of percentage shortening of left ventricular transverse hemiaxes (0.3+/-0.1 versus 0.5+/-0.1, P=0.001) compared with group 2. Group 1 had higher A wave peak velocity (78+/-18 versus 60+/-20 cm/s, P=0.048), lower E/A ratio (0.9+/-0.3 versus 1.5+/-0.6, P=0.02) and slower E wave deceleration time (204+/-51 versus 155+/-50 ms, P=0.047) compared with group 2. Semiquantitative histologic scores did not differ significantly between groups. There was no significant correlation between histologic variables and left ventricular systolic and diastolic indexes. Thus, dilated cardiomyopathy shows borderline to severe left ventricular systolic impairment and distinct left ventricular diastolic filling abnormalities, according to the clinical stage. This study suggests a marked dissociation between histologic findings and functional abnormalities in early and advanced dilated cardiomyopathy.

Right ventricular filling in dilated cardiomyopathy

PURPOSE

To assess right ventricular filling in dilated cardiomyopathy.

PATIENTS

32 patients with dilated cardiomyopathy and 24 healthy controls.

METHODS

Stroke distances were measured by pulsed Doppler echocardiography at left ventricular outflow and left and right ventricular inflow. The inflow tract dimensions of both ventricles and the outflow tract dimension of the left ventricle were measured from two dimensional images. Right and left sided atrioventricular (AV) ring excursions were measured by M mode echocardiography at the tricuspid and mitral rings. Stroke volume was derived as stroke distance multiplied by left ventricular outflow tract area. Total stroke distances were calculated as the sum of AV valve Doppler stroke distances and ring excursion. The effective orifice areas of the two AV valves were thus defined as stroke volumes divided by total stroke distance.

RESULTS

Total tricuspid stroke distance was normally less than mitral (6.0 (1.7) v 7.6 (1.7) cm, P < 0.05), implying that effective orifice area of the tricuspid valve was consistently greater (6.6 (1.6) v 4.5 (0.8) cm2, P < 0.01). Total tricuspid ring excursion was normally more than mitral (2.30 (0.30) v 1.62 (0.22) cm, P < 0.01). Total tricuspid stroke distance in dilated cardiomyopathy was also less than mitral (7.8 (2.4) v 9.7 (2.8) cm, P < 0.05). Tricuspid stroke distance was significantly increased in patients with dilated cardiomyopathy compared with that in healthy controls (P < 0.05 v controls), though stroke volume was much smaller (26 (10) v 63 (11) ml, P < 0.01) so that tricuspid effective orifice area was reduced to less than half normal (2.7 (1.2) cm2, P < 0.01). Total tricuspid ring long axis excursion was more than mitral (1.37 (0.6) v 0.74 (0.21) cm, P < 0.01). Right ventricular end diastolic inflow dimension was increased compared with that in healthy controls (3.9 (0.7) v 2.8 (0.5) cm, P < 0.01), correlating inversely with tricuspid effective orifice area (r = -0.71, P < 0.01). Total tricuspid ring excursion was bimodally distributed as a low amplitude group (less than 1.6 cm, n = 23) and a high amplitude group (more than 1.6 cm, n = 9), in which the interval P2 to onset of tricuspid flow was much longer (100 (35) v 50 (14) ms, P < 0.01).

CONCLUSIONS

Enlargement of the right ventricular inflow tract in dilated cardiomyopathy, especially to more than 5 cm, is accompanied by a progressive decrease in effective tricuspid orifice area, sometimes to less than 1 cm2 and increased inflow velocities. Right ventricular relaxation was incoordinate in 28% of the patients studied. These disturbances of right ventricular filling are likely to compromise overall cardiac function independently of left ventricular disease.

Detection of unique transmural architecture of human idiopathic cardiomyopathy by ultrasonic tissue characterization

BACKGROUND

Noninvasive approaches to the evaluation of idiopathic cardiomyopathy are limited. Recent work from our laboratory has used quantitative ultrasound to define the three-dimensional structure of normal human myocardium and the myocardial remodeling associated with infarction. Our goal was to define the role of ultrasonic tissue characterization for detection of specific alterations in the three-dimensional transmural architecture of idiopathic dilated cardiomyopathy.

METHODS AND RESULTS

We measured frequency-dependent backscatter from 22 cylindrical biopsy specimens from nine explanted fixed hearts of patients who underwent heart transplantation for idiopathic cardiomyopathy, seven specimens from normal portions, and 12 specimens of infarcted tissue from six explanted fixed human hearts. Consecutive transmural levels from each specimen were insonified with a 5-MHz broadband transducer. The dependence of apparent (uncompensated for attenuation) backscatter, B(f), on frequency (f) was computed from radiofrequency (rf) data as: magnitude of B(f)2 = afn, where n is an index that reflects in part the size of the dominant scatterers in myocardial tissue. Myofiber diameter and percentage fibrosis were determined at each transmural level for each specimen. For cardiomyopathic tissue, the frequency dependence of backscatter (n) increased progressively from epicardial to endocardial (0.02 +/- 0.37 to 1.01 +/- 0.12, p less than 0.05) levels in conjunction with a progressive decrease in myofiber diameter (29.5 +/- 0.9 to 21.4 +/- 0.6 microns, p less than 0.0001). In contrast, in tissue from areas of infarction, the frequency dependence decreased progressively from epicardium to endocardium (0.91 +/- 0.20 to 0.23 +/- 0.21, p less than 0.05) in conjunction with a progressive increase in the percentage of fibrosis (23.5 +/- 9.4% to 54.5 +/- 4.9%, p less than 0.005). Normal tissue exhibited no significant transmural trend for frequency dependence, myofiber diameter, or percentage fibrosis.

CONCLUSIONS

These data indicate the presence of a heterogenous transmural distribution of scattering structures associated with human idiopathic cardiomyopathy and myocardial infarction that may be detected by ultrasonic tissue characterization. The divergence of these transmural trends for frequency dependence of backscatter reflects distinct mechanisms of structural heterogeneity for different pathological processes that comprise a transmural gradation of cell size and fibrosis for idiopathic cardiomyopathy and infarction, respectively.

Endomyocardial biopsy in infants and children with cardiomyopathy

We reviewed our experience of endomyocardial biopsy performed on 21 symptomatic infants and children with cardiomyopathy. Clinical congestive cardiomyopathy was noted in 18 patients, 2 had hypertrophic cardiomyopathy, and 1 a restrictive cardiomyopathy. The biopsy findings led to a diagnosis of hemochromatosis in one patient, Adriamycin cardiomyopathy in another, and lymphocytic myocarditis in a third. Five patients had features of endocardial fibroelastosis, one endomyocardial fibrosis, and a further one, a mitochrondrial abnormality. In 11 patients normal or nonspecific features were seen. There were 2 myocardial perforations, both patients being successfully resuscitated. Endomyocardial biopsy, although occasionally hazardous, may sometimes provide valuable information which may lead to a diagnosis, facilitate treatment, and be of prognostic value. Despite the low positive yield, it may still be indicated in selected patients, in view of the seriousness and often poor prognosis of this disorder: 5 of our study group subsequently died.

Myocarditis: unresolved issues in diagnosis and treatment

Myocarditis is an enigmatic disease. Lymphocytic myocarditis is most commonly viral in origin. Considerable evidence suggests that myocardial damage is due to an immune-mediated mechanism rather than to direct effects of the virus itself. The presentation is variable, ranging from a clinically inapparent or relatively benign illness to acute progressive heart failure and death. Although examination of the endomyocardial biopsy specimen is the "gold standard" for the diagnosis of myocarditis there are problems with this technique, relating particularly to sampling error and histologic interpretation. Considerable evidence, both animal and human, suggests that a link between viral myocarditis and dilated cardiomyopathy does exist. There is a rational basis for the use of immunosuppressive therapy in myocarditis. Although many favorable responses have been reported with the use of these agents, the results of more definitive studies are awaited to determine the role of immunosuppressive therapy in myocarditis more clearly. Recommendations for the practical management of patients with myocarditis are made. Whenever possible, patients with this diagnosis should be entered into the ongoing NIH trial.

Endomyocardial biopsy in infants and children: experience in 60 patients

In 60 children, aged between 1 month and 22 years (median 3.54 years) and with a body weight of 3-67 kg (median 12.6 kg), transvascular endomyocardial biopsy (EMB) was performed from the right (35 children) or left ventricle (30 children). The specimens were investigated by light and electron microscopy. There were three indications for biopsy: (1) poorly functioning, dilated left ventricle (seven patients with endocardial fibroelastosis, 16 with dilated cardiomyopathy, six from healing/healed or chronic myocarditis); (2) unexplained left ventricular hypertrophy (10 with hypertrophic cardiomyopathy, four with secondary hypertrophy, three with storage diseases); (3) to answer certain questions in eight children (four with hypoxic and two with cytoxic myocardial damage). Retrospectively, there were five nonindicated biopsies. There were no serious complications. Biopsies were diagnostic in 11.7% of cases, helpful in 71.7%, and of no help in 16.6%. Thus even in childhood endomyocardial biopsy is a diagnostic tool which can add useful information on the etiology or pathogenesis of an underlying myocardial disease.

Predictive value of immunofluorescence and electron microscopic evaluation of endomyocardial biopsies in the diagnosis and prognosis of myocarditis and idiopathic dilated cardiomyopathy

The distinction between idiopathic dilated cardiomyopathy and myocarditis is controversial, both clinically and pathologically. To increase diagnostic accuracy and provide prognostic information, we prospectively tested the routine application of immunofluorescence and electron microscopy in endomyocardial biopsy evaluation. Biopsy samples from a consecutive series of 79 patients with cardiomyopathy and possible myocarditis were thus evaluated by light (LM), immunofluorescence (IF), and electron microscopy (EM). Patient course was followed prospectively to determine prognostic factors. Immunoglobulin (IgG) and complement (C) in biopsy tissue were graded 0 to 3+ and an IF score was derived as 2 (IgG) grade + C grade. A highly significant association was found between IF score greater than or equal to 2 and the presence of mononuclear cells (lymphocytes plus macrophages) greater than 5/high-power field, confirmed by EM; 12 of 15 (80%) with IF score greater than or equal to 2 had inflammatory cells, vs only 2 of 64 (3%) with IF score less than 2 (p less than 0.000001). EM was used to confirm the identity of infiltrating cells and to grade myofilament loss (0 to 3+) and 11 other ultrastructural features. EM did not provide important predictive information in myocarditis, but confirmed the presence of inflammatory cells. However, the EM finding of myofilament loss provided prognostic information both in patients with and without myocarditis (p less than 0.03). Mortality at 18 months was 37% for patients with 2 to 3+ myofilament loss, vs 10% in those with 0 to 1+ loss. Moreover, myofilament loss was prognostically independent of clinical class and ejection fraction. EM determination of myofilament loss is valuable as a prognostic indicator, whether or not myocarditis is present. Routine IF and EM increase the diagnostic accuracy and prognostic information in endomyocardial biopsies from patients with suspected myocarditis or cardiomyopathy.

Clinical experience with two-dimensional echocardiography to guide endomyocardial biopsy

Two-dimensional echocardiography was used to aid right ventricular endomyocardial biopsy during 163 procedures in 83 patients being evaluated for myocarditis, cardiac transplant rejection, or drug toxicity. Thirty procedures were performed using combined echocardiography and fluoroscopy and 133 using echocardiography alone. For 80 of the 83 patients (96%) the forceps could be adequately visualized entering the right atrium, crossing the tricuspid valve, and advancing to the right ventricular apex and free wall. The catheter could be guided to biopsy the septum and sample multiple, separate sites along the right ventricular walls. By opening the forceps prior to contact with the myocardium, the right ventricular free wall could be biopsied without perforation. We found two-dimensional echocardiography to be a useful and safe technique for forceps visualization and manipulation in the right ventricle.

Endomyocardial biopsy: a review of the literature

A review of the literature relating to endomyocardial biopsy (EMB) is presented. This is considered important at this time since EMB is being utilized with increasing frequency, particularly for the diagnosis of myocarditis. The development of the technique is briefly outlined. Emphasis is placed on the clinical application of EMB in the various primary cardiomyopathies (dilated, hypertrophic, restrictive, and obliterative), the infiltrative secondary cardiomyopathies (amyloidosis, sarcoidosis, hemochromatosis), myocarditis, as well as such conditions as adriamycin cardiotoxicity, cardiac transplant rejection, and Kawasaki disease. More controversial application of EMB in primary mitral valve prolapse (Barlow's syndrome), idiopathic ventricular arrhythmias, and the elucidation of the enigmatic finding of angina with angiographically normal coronary arteries is detailed. Experience with immunological and biochemical investigation of biopsy material, as well as with virus isolation and drug assays in the myocardium, is alluded to. Complications encountered with this procedure are also discussed, and its future role is contemplated.

Findings on endomyocardial biopsy in infants and children with dilated cardiomyopathy

Fifteen infants and children with dilated cardiomyopathy underwent transvascular endomyocardial biopsy. The light and electron microscopic findings were reviewed to evaluate the presence of lymphocytes as an indicator of active myocarditis. Both ventricles were biopsied in 13 patients, and the right ventricle only was biopsied in 2. None of the endomyocardial specimens obtained by biopsy revealed an inflammatory process. Interstitial fibrosis, myofiber hypertrophy, degeneration and necrosis were found. Ultrastructural abnormalities of the mitochondria, T tubules or Z bands were noted in approximately one-third of patients. Persistent, active myocarditis is an uncommon cause of dilated cardiomyopathy in children. Immunosuppressive therapy, which may be harmful, should be considered only after myocardial inflammation has been documented by endomyocardial biopsy.

Gallium-67 imaging in patients with dilated cardiomyopathy and biopsy-proven myocarditis

Current standards for detection of myocarditis in a clinical setting rely on endomyocardial biopsy for accurate diagnosis. With this technique a subset of patients with dilated cardiomyopathy show unsuspected myocarditis histologically. Endomyocardial biopsy, despite its specificity, may lack sensitivity due to sampling error if the inflammation is patchy or focal. Therefore, inflammation-sensitive radioisotopic imaging may be a useful adjunct in the diagnosis of myocarditis. This study was designed to evaluate the applicability of gallium-67 (67Ga) myocardial imaging as an adjunct to endomyocardial biopsy in the diagnosis of myocarditis. Sixty-eight consecutive patients referred for evaluation of dilated cardiomyopathy underwent 71 parallel studies with 67Ga imaging and biopsies that served as the basis of comparison for this study. Histologic myocarditis was identified in 8% of biopsy specimens. Clinical and hemodynamic parameters could not be used to predict the presence of myocarditis. Five of six biopsy samples (87%) with myocarditis showed dense 67Ga uptake, whereas only nine of 65 negative biopsy samples (14%) were paired with equivocally positive 67Ga scans (p less than .001). The single patient with myocarditis and no myocardial 67Ga uptake had dense mediastinal lymph node uptake that may have obscured cardiac uptake. The incidence of myocarditis on biopsy with a positive 67Ga scan was 36% (5/14); however, the incidence of myocarditis with a negative 67Ga scan was only 1.8% (1/57). Follow-up scans for three patients showed close correlation of 67Ga uptake with myocarditis on biopsy. In conclusion 67Ga may be a useful screening test for identifying patients with a high yield of myocarditis on biopsy, and serial scans may eliminate the need for frequent biopsies in patients with proven myocarditis.

The femoral venous approach to endomyocardial biopsy: comparison with internal jugular and transarterial approaches

Endomyocardial biopsy is often used in the clinical evaluation of cardiac disease. Among 134 consecutive procedures (280 myocardial samples), 3 approaches were compared: right internal jugular (n = 69), femoral arterial (n = 30) and femoral venous (n = 35). The femoral venous approach is a new method with which a preformed guiding sheath is used to allow sampling of the apical right ventricular portion of the ventricular septum. Vascular access and myocardial sampling were successful in all femoral venous and left ventricular (LV) procedures; however, the internal jugular vein could not be located to allow biopsy in 12% of neck approaches (p less than 0.025). One case of pneumothorax occurred after an internal jugular approach. Chest pain occurred after 10% (3 patients) of the LV, 4% (3 patients) of internal jugular and 3% (1 patient) of femoral venous procedures. Hypotension associated with biopsy was noted after 3 internal jugular and 2 LV procedures. Pericardial effusion was observed in 3 patients after an LV procedure (p less than 0.01). In 1 of these patients tamponade developed. The femoral venous approach had the highest overall efficiency (successful biopsy, lack of adverse events, p less than 0.05). This approach may become the procedure of choice for routine endomyocardial biopsy because it allows reliable vascular access and myocardial sampling with a low incidence of adverse reactions.

High incidence of myocarditis by endomyocardial biopsy in patients with idiopathic congestive cardiomyopathy

Thirty-five patients with unexplained congestive heart failure were evaluated with endomyocardial biopsy. Utilizing microscopic, ultrastructural and immunofluorescent studies, samples were classified as exhibiting either no inflammation (cardiomyopathy) or active lymphocytic myocarditis, grade I to IV. Twenty-two (63%) of the patients had inflammatory changes. Of these 22 patients, 18 had low grade I or II inflammation, 7 were treated with immunosuppressive agents with improvement in 5 and stabilization in 1. One patient died of progressive congestive heart failure. Three of four patients with high grade III or IV myocarditis died after a fulminant course. The results suggest that inflammatory myocarditis may be more common than previously suspected and add evidence that there may be ongoing inflammation in many cases of congestive cardiomyopathy.