Functional and histopathologic correlation in patients with dilated cardiomyopathy: an integrated evaluation by multivariate analysis

Impact of Functional Mitral Regurgitation on Left Ventricular Strain in Nonischemic Dilated Cardiomyopathy Patients with Type 2 Mellitus Diabetes: A Magnetic Resonance Feature Tracking Study

BACKGROUND

The impact of functional mitral regurgitation and type 2 mellitus diabetes (T2DM) on left ventricular (LV) strain in nonischemic dilated cardiomyopathy (NIDCM) patients remains unclear.

PURPOSE

To evaluate the impact of mitral regurgitation severity on LV strain, and explore additive effect of T2DM on LV function across varying mitral regurgitation severity levels in NIDCM patients.

STUDY TYPE

Retrospective.

POPULATION

352 NIDCM (T2DM-) patients (49.1 ± 14.6 years, 67% male) (207, 85, and 60 no/mild, moderate, and severe mitral regurgitation) and 96 NIDCM (T2DM+) patients (55.2 ± 12.4 years, 77% male) (47, 30, and 19 no/mild, moderate, and severe mitral regurgitation).

FIELD STRENGTH/SEQUENCE

3.0 T/balanced steady-state free precession sequence.

ASSESSMENT

LV geometric parameters and strain were measured and compared among groups. Determinants of LV strain were investigated.

STATISTICAL TEST

Student's t-test, Mann-Whitney U test, one-way ANOVA, Kruskal-Wallis test, univariable and multivariable linear regression. P < 0.05 was considered statistically significant.

RESULTS

LV GLPS and longitudinal PDSR decreased gradually with increasing mitral regurgitation severity in NIDCM patients with T2DM(GLPS: -5.7% ± 2.1% vs. -4.3% ± 1.6% vs. -2.6% ± 1.3%; longitudinal PDSR:0.5 ± 0.2 sec-1 vs. 0.4 ± 0.2 sec-1 vs. 0.3 ± 0.1 sec-1). NIDCM (T2DM+) demonstrated decreased GCPS and GLPS in the no/mild subgroup, reduced LV GCPS, GLPS, and longitudinal PDSR in the moderate subgroup, and reduced GRPS, GCPS, GLPS, and longitudinal PDSR in the severe subgroup compared with NIDCM (T2DM-) patients. Multivariable regression analysis identified that mitral regurgitation severity (β = -0.13, 0.15, and 0.25 for GRPS, GCPS, and GLPS) and the presence of T2DM (β = 0.14 and 0.13 for GCPS and GLPS) were independent determinants of LV strains in NIDCM patients.

DATA CONCLUSION

Increased mitral regurgitation severity is associated with reduced LV strains in NIDCM patients with T2DM. The presence of T2DM exacerbated the decline of LV function across various mitral regurgitation levels in NIDCM patients, resulting in reduced LV strains.

LEVEL OF EVIDENCE: 3

TECHNICAL EFFICACY

Stage 3.

Sudden cardiac death: A comparative review of humans, dogs and cats

Sudden death is one of the most common causes of death in humans in Western countries. Approximately 85% of these cases are of cardiac origin. In dogs and cats, sudden cardiac death (SCD) also commonly occurs, but fewer pathophysiological and prevalence data are available. Both structural, primarily 'electrical' and ischemic heart diseases are known to cause SCD, many of which share similar underlying arrhythmogenic mechanisms between humans and companion animals. As for underlying genetics, numerous mutations on multiple loci have been related to SCD in humans, but only a few mutations associated with dilated cardiomyopathy and SCD have been identified in dogs, e.g. in the phospholamban and titin genes. Information published from human medicine can therefore inform future veterinary studies, but also dogs and cats could act as spontaneous models of SCD in humans. Further research in both fields is therefore warranted to better understand the pathophysiology, genetics, and prevention of SCD.

Simple Electrocardiographic Score Can Predict Left Ventricular Reverse Remodeling in Patients With Non-Ischemic Cardiomyopathy

Background: Left ventricular reverse remodeling (LVRR) is a favorable response in non-ischemic, non-valvular cardiomyopathy (NICM) patients. Recently, 18-lead body surface electrocardiography (ECG), the standard 12-lead ECG with synthesized right-sided/posterior chest leads, has been developed, but its predictive value for LVRR has not been evaluated.

Methods and Results: Of 216 consecutive hospitalized NICM patients with LV ejection fraction (LVEF) ≤35%, we studied 125 who received optimization of their heart failure treatment and had 18-lead ECG and echocardiography data available for evaluating LVRR, defined as an absolute increase in LVEF ≥10% concomitant with LVEF ≥35% after 1-year optimized treatment. Most 18-lead ECG parameters in the NICM patients differed from those in 312 age- and body mass index-matched subjects with normal echocardiography. LVRR occurred in 59 NICM patients and they had a larger QRS amplitude in the limb leads (I, II, aVR, and aVF), precordial leads (V3–V6), and synthesized leads (syn-V4R–5R), decreased QRS axis and duration, and lower prevalence of fragmented QRS than those without LVRR. The ECG score using 3 selected parameters (QRS amplitude in aVR ≥675 µV; QRS duration <106 ms without fragmentation; and QRS axis <67°) was associated with the incidence of LVRR even after adjusting for optimized treatment.

Conclusions: The standard 12-lead ECG parameters are sufficiently predictive of LVRR in NICM patients.

Assessment of Remote Myocardium Heterogeneity in Patients with Ventricular Tachycardia Using Texture Analysis of Late Iodine Enhancement (LIE) Cardiac Computed Tomography (cCT) Images

Purpose

Diffuse remodeling of myocardial extra-cellular matrix is largely responsible for left ventricle (LV) dysfunction and arrhythmias. Our hypothesis is that the texture analysis of late iodine enhancement (LIE) cardiac computed tomography (cCT) images may improve characterization of the diffuse extra-cellular matrix changes. Our aim was to extract volumetric extracellular volume (ECV) and LIE texture features of non-scarred (remote) myocardium from cCT of patients with recurrent ventricular tachycardia (rVT), and to compare these radiomic features with LV-function, LV-remodeling, and underlying cardiac disease.

Procedures

Forty-eight patients suffering from rVT were prospectively enrolled: 5/48 with idiopathic VT (IVT), 23/48 with post-ischemic dilated cardiomyopathy (ICM), 9/48 with idiopathic dilated cardiomyopathy (IDCM), and 11/48 with scars from a previous healed myocarditis (MYO). All patients underwent echocardiography to assess LV systolic and diastolic function and cCT with pre-contrast, angiographic, and LIE scan to obtain end-diastolic volume (EDV), ECV, and first-order texture parameters of Hounsfield Unit (HU) of remote myocardium in LIE [energy, entropy, HU-mean, HU-median, standard deviation (SD), and mean absolute deviation (MAD)].

Results

Energy, HU mean, and HU median by cCT texture analysis correlated with ECV (rho = 0.5650, rho = 0.5741, rho = 0.5068; p < 0.0005). cCT-derived ECV, HU-mean, HU-median, SD, and MAD correlated directly to EDV by cCT and inversely to ejection fraction by echocardiography (p < 0.05). SD and MAD correlated with diastolic function by echocardiography (rho = 0.3837, p = 0.0071; rho = 0.3330, p = 0.0208). MYO and IVT patients were characterized by significantly lower values of SD and MAD when compared with ICM and IDCM patients, independently of LV-volume systolic and diastolic function.

Conclusions

Texture analysis of LIE may expand cCT capability of myocardial characterization. Myocardial heterogeneity (SD and MAD) was associated with LV dilatation, systolic and diastolic function, and is able to potentially identify the different patterns of structural remodeling characterizing patients with rVT of different etiology.

Decompensated Heart Failure With Ventricular Arrhythmia: How Useful Is VT Ablation?

PURPOSE OF REVIEW

Ventricular arrhythmias are common in patients with heart failure. Their management especially in the context of decompensated heart failure poses a clinical challenge to modern cardiologists. In this review article, we aim to summarise the current evidence on the epidemiology, pathophysiology, and management of ventricular tachycardia in heart failure, focusing primarily on the use of catheter ablation.

RECENT FINDINGS

The evolution of electro-anatomical mapping techniques and ablation catheter technology in the recent years has paved the path for the successful application of catheter ablation in the treatment of ventricular arrhythmias. The efficacy of catheter ablation in the management of ventricular tachycardia in patients with chronic heart failure has recently been the epicentre of a number of randomised controlled trials, demonstrating promising results with regard to arrhythmia suppression and all-cause mortality. The usefulness of catheter ablation in decompensated heart failure has been explored to a lesser degree, primarily in the setting of an electrical storm. Implantable cardiac defibrillators play the most important role in improving prognosis and preventing sudden cardiac death in patients with heart failure. Catheter ablation for the treatment of recurrent VT in patients with chronic heart failure is an efficacious strategy that can be applied adjunctively to or in instead of antiarrhythmic therapy, and it is highly successful at preventing recurrent ventricular tachycardia, ICD shocks. Its efficacy in the context of decompensated heart failure requires further research, with current evidence rendering its use promising.

Catheter Ablation of Ventricular Tachycardia in Structural Heart Disease: Indications, Strategies, and Outcomes-Part II

In contrast to ventricular tachycardia (VT) that occurs in the setting of a structurally normal heart, VT that occurs in patients with structural heart disease carries an elevated risk for sudden cardiac death (SCD), and implantable cardioverter-defibrillators (ICDs) are the mainstay of therapy. In these individuals, catheter ablation may be used as adjunctive therapy to treat or prevent repetitive ICD therapies when antiarrhythmic drugs are ineffective or not desired. However, certain patients with frequent premature ventricular contractions (PVCs) or VT and tachycardiomyopathy should be considered for ablation before ICD implantation because left ventricular function may improve, consequently decreasing the risk of SCD and obviating the need for an ICD. The goal of this paper is to review the pathophysiology, mechanism, and management of VT in the setting of structural heart disease and discuss the evolving role of catheter ablation in decreasing ventricular arrhythmia recurrence.

Utility of High-Resolution Magnetocardiography to Predict Later Cardiac Events in Nonischemic Cardiomyopathy Patients With Normal QRS Duration

BACKGROUND

Nonischemic dilated cardiomyopathy (NIDCM) patients, even those with a narrow QRS, are at increased risk for major adverse cardiac events (MACE). We hypothesized that 64-channel magnetocardiography (MCG) would be useful to detect prognostic left intraventricular disorganized conduction (LiDC) by overcoming the limitations of fragmented QRS (fQRS, qualitative definitions, low specificity) and late potential (abnormality undetectable in earlier QRS).Methods and Results:We evaluated LiDC on MCG, defined as significant deviation from a global clockwise left ventricular (LV) activation pattern, and conventional noninvasive predictors of MACE, including fQRS and late potential, in 51 NIDCM patients with narrow QRS (LV ejection fraction, 22±7%; QRS duration, 99±11 ms). MACE was defined as cardiac death, lethal ventricular arrhythmias, or LV assist device (LVAD) implantation. LiDC was present in 22 patients. Baseline characteristics were comparable between patients with and without LiDC, except for the ratio of positive late potential. During a mean follow-up of 2.9 years, MACE developed in 16 NIDCM patients (3 cardiac deaths, 9 lethal ventricular arrhythmias, and 4 LVAD). MACE was more incident in patients with LiDC (13/22) than in those without (3/29, P<0.001). Multivariate analysis revealed LiDC, but not fQRS or late potential, as the strongest independent predictor of MACE (hazard ratio 4.28, 95% confidence interval 1.30-19.39, P=0.015).

CONCLUSIONS

MCG accurately depicts LiDC, a promising noninvasive predictor of MACE in patients with NIDCM and normal QRS.

L71F mutation in rat cardiac troponin T augments crossbridge recruitment and detachment dynamics against α-myosin heavy chain, but not against β-myosin heavy chain

The N-terminal extension of human cardiac troponin T (TnT), which modulates myofilament Ca²⁺ sensitivity, contains several hypertrophic cardiomyopathy (HCM)-causing mutations including S69F. However, the functional consequence of S69F mutation is unknown. The human analog of S69F in rat TnT is L71F (TnT_L71F). Because the functional consequences due to structural changes in the N-terminal extension are influenced by the type of myosin heavy chain (MHC) isoform, we hypothesized that the TnT_L71F-mediated effect would be differently modulated by α- and β-MHC isoforms. TnT_L71F and wild-type rat TnT were reconstituted into de-membranated muscle fibers from normal (α-MHC) and propylthiouracil-treated rat hearts (β-MHC) to measure steady-state and dynamic contractile parameters. The magnitude of the TnT_L71F-mediated attenuation of Ca²⁺-activated maximal tension was greater in α- than in β-MHC fibers. For example, TnT_L71F attenuated maximal tension by 31% in α-MHC fibers but only by 10% in β-MHC fibers. Furthermore, TnT_L71F reduced myofilament Ca²⁺ sensitivity by 0.11 pCa units in α-MHC fibers but only by 0.05 pCa units in β-MHC fibers. TnT_L71F augmented rate constants of crossbridge recruitment and crossbridge detachment dynamics in α-MHC fibers but not in β-MHC fibers. Collectively, our data demonstrate that TnT_L71F induces greater contractile deficits against α-MHC than against β-MHC background.

The evaluation of non-ischemic dilated cardiomyopathy with T1 mapping and ECV methods using 3T cardiac MRI

PURPOSE

The aim of this study was to examine the correlation between ventricular function and the extracellular volume fraction (ECV) in patients with non-ischemic dilated cardiomyopathy (NIDCM) using 3.0 T magnetic resonance imaging (MRI). We also hypothesized that native T1 and ECV values would be increased in patients with NIDCM, independent of the left ventricular ejection fraction (LVEF). The findings of our study could lead to further studies of the follow-up protocols.

MATERIALS AND METHODS

In total, 53 consecutive dilated cardiomyopathy patients who had undergone cardiac MRI were functionally evaluated and underwent tissue characterization.

RESULTS

The mean native T1 value was 1235 ± 10 ms, and the mean ECV value was 35.4 ± 2.7% in the myocardia. The LVEF values ranged from 29 to 44%. No significant correlations were observed between functional analysis measurements and native T1 or ECV values.

CONCLUSIONS

Our results showed that myocardial fibrosis is unrelated to cardiac functional findings in NIDCM patients. Therefore, we propose that these patients should be evaluated using MRI and tissue characterization techniques, in addition to cardiac functional analysis.

Pathologic Manifestations on Surgical Biopsy and Their Correlation with Clinical Indices in Dogs with Degenerative Mitral Valve Disease

BACKGROUND

Evaluation of myocardial function is clinically challenging in dogs with degenerative mitral valve disease (DMVD). Although myocardial dysfunction is caused by pathologic degeneration, histopathologic progression is poorly understood.

OBJECTIVES

To characterize myocardial and pulmonary pathologic changes according to severity in dogs with naturally occurring DMVD, and to investigate whether or not pathologic degeneration is reflected by traditional clinical indices.

ANIMALS

One hundred and seventeen dogs with naturally occurring DMVD.

METHODS

Prospective observational study. Biopsied left atrium (LA), left ventricle (LV), and lung were evaluated histologically, and an attempt was made to correlate pathologic findings with clinical indices.

RESULTS

Severe myocardial changes were observed in all International Small Animal Cardiac Health Council classes. In the lung, heart failure cell levels were significantly increased in class III patients (P < .0001). In a paired comparison, the LA showed significantly more severe degeneration than the LV, including myocardial fatty replacement, immune cell infiltration, and interstitial fibrosis (P < .0001). In contrast, myocardial cells were more hypertrophied in the LV than in the LA (P < .0001). Left ventricular end-diastolic dimension (LVEDd) was associated with fatty replacement (P = .033, R(2) = 0.584) and myocardial vacuolization (P = .003, R(2) = 0.588) in the LA.

CONCLUSIONS AND CLINICAL IMPORTANCE

In DMVD, although severe pathologic changes may be evident even in early stages, there may be pathologic discrepancy between the LA and the LV. Myocardial degeneration may be reflected by clinical indices such as LVEDd and EF.

Left ventricular regional shape dynamics analysis by three-dimensional cardiac magnetic resonance imaging associated with left ventricular function in first-time myocardial infarction patients

Geometric remodelling of the left ventricle (LV) following myocardial infarction reflects on the geometric characteristics directly. This study focuses on a potential index based on curvedness. Nine consecutive normal volunteers and thirty consecutive myocardial infarction patients underwent MRI scan (twenty-seven patients had follow-up scan). Short-axis cine images of all cases were delineated. Three dimensional LV models were reconstructed and restored for possible motion distortion. The curvedness values were computed over 16-segments nomenclature. The curvedness signal for each segment over twenty-two time frames were fitted using a second order Fourier Series. Fourier coefficients were extracted and unsupervised learning was conducted between normal and patient data. An accuracy of 89% and adjusted Rand Index of 0.5374 suggest that these Fourier Series and curvedness based features can be an useful index for prognosis and diagnosis in clinical practice.

Passive ventricular remodeling in cardiac disease: focus on heterogeneity

Passive ventricular remodeling is defined by the process of molecular ventricular adaptation to different forms of cardiac pathophysiology. It includes changes in tissue architecture, such as hypertrophy, fiber disarray, alterations in cell size and fibrosis. Besides that, it also includes molecular remodeling of gap junctions, especially those composed by Connexin43 proteins (Cx43) in the ventricles that affect cell-to-cell propagation of the electrical impulse, and changes in the sodium channels that modify excitability. All those alterations appear mainly in a heterogeneous manner, creating irregular and inhomogeneous electrical and mechanical coupling throughout the heart. This can predispose to reentry arrhythmias and adds to a further deterioration into heart failure. In this review, passive ventricular remodeling is described in Hypertrophic Cardiomyopathy (HCM), Dilated Cardiomyopathy (DCM), Ischemic Cardiomyopathy (ICM), and Arrhythmogenic Cardiomyopathy (ACM), with a main focus on the heterogeneity of those alterations mentioned above.

Impact of diabetes mellitus on myocardial lipid deposition: an autopsy study

Lipid accumulation in the cardiac parenchyma has historically been known as fatty heart. Myocardial lipotoxicity and cardiac steatosis have been shown to be involved in the pathogenesis of obesity and diabetic mellitus (DM). Mutated adipose triglyceride lipase (ATGL), a key catalytic enzyme of triglyceride, has been found to cause human triglyceride deposit cardiomyovasculopathy (TGCV). Nevertheless, the significance of fatty heart in the disease process is still unclear. Here, we investigated myocardial lipid deposition (LD) in 73 autopsy cases. Nile blue staining revealed seven cases (9.5%) showing LD with elevated tissue triglyceride content, all of which suffered from DM. Immunohistochemically, ATGL expression was preserved in all tested cases. Rates of myocardial infarction and heart failure were higher in LD/DM cases than in non-LD cases. Semi-quantitative histological analysis revealed no significant differences in the degree of myocardial hypertrophy, myofibrillar loss, fibrosis, small vascular disease, inflammation or fat invasion between LD/DM and non-LD cases. However, more severe histological damage was seen in DM cases than in non-DM cases. Our data suggest that DM is a major risk for fatty heart with myocardial LD based on recent autopsy cases.

The effect of cardiac fibrosis on left ventricular remodeling, diastolic function, and N-terminal pro-B-type natriuretic peptide levels in patients with nonischemic dilated cardiomyopathy

BACKGROUND

Cardiac fibrosis is common and associated with poor prognosis in patients with heart failure. We investigated the effect of cardiac fibrosis on the left ventricular (LV) diastolic function, functional capacity, LV remodeling, and biochemical parameters in patients with nonischemic dilated cardiomyopathy (NIDC). In addition, we investigated the biochemical and echocardiographic predictors of cardiac fibrosis in this group.

METHODS AND RESULTS

Forty patients with NIDC were enrolled. Cardiac fibrosis was evaluated according to the presence of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging. Nineteen patients had cardiac fibrosis (Group I) and 21 patients did not have cardiac fibrosis (Group II). LV systolic and diastolic parameters were assessed with conventional and tissue Doppler echocardiography. N-terminal pro-B-type natriuretic peptide (NT-pro BNP) levels of each patient were recorded. Patients with cardiac fibrosis had impaired diastolic function, higher functional class and NT-pro BNP levels, and significant LV remodeling than the patients without cardiac fibrosis. A correlation analysis revealed that the cardiac fibrosis severity was associated with functional class, cardiac chamber sizes, NT-pro BNP levels, diastolic parameters such as E/Se. A linear regression analysis demonstrated that NT-pro BNP and E/Se were the independent predictors of cardiac fibrosis.

CONCLUSION

Cardiac fibrosis correlates with impaired LV diastolic function and functional capacity, elevated NT-proBNP levels, and adverse cardiac remodeling in patients with NIDC. Therefore, the assessment of cardiac fibrosis can be useful in the management of these patients.

Left ventricular regional wall curvedness and wall stress in patients with ischemic dilated cardiomyopathy

Geometric remodeling of the left ventricle (LV) after myocardial infarction is associated with changes in myocardial wall stress. The objective of this study was to determine the regional curvatures and wall stress based on three-dimensional (3-D) reconstructions of the LV using MRI. Ten patients with ischemic dilated cardiomyopathy (IDCM) and 10 normal subjects underwent MRI scan. The IDCM patients also underwent delayed gadolinium-enhancement imaging to delineate the extent of myocardial infarct. Regional curvedness, local radii of curvature, and wall thickness were calculated. The percent curvedness change between end diastole and end systole was also calculated. In normal heart, a short- and long-axis two-dimensional analysis showed a 41 +/- 11% and 45 +/- 12% increase of the mean of peak systolic wall stress between basal and apical sections, respectively. However, 3-D analysis showed no significant difference in peak systolic wall stress from basal and apical sections (P = 0.298, ANOVA). LV shape differed between IDCM patients and normal subjects in several ways: LV shape was more spherical (sphericity index = 0.62 +/- 0.08 vs. 0.52 +/- 0.06, P < 0.05), curvedness at end diastole (mean for 16 segments = 0.034 +/- 0.0056 vs. 0.040 +/- 0.0071 mm(-1), P < 0.001) and end systole (mean for 16 segments = 0.037 +/- 0.0068 vs. 0.067 +/- 0.020 mm(-1), P < 0.001) was affected by infarction, and peak systolic wall stress was significantly increased at each segment in IDCM patients. The 3-D quantification of regional wall stress by cardiac MRI provides more precise evaluation of cardiac mechanics. Identification of regional curvedness and wall stresses helps delineate the mechanisms of LV remodeling in IDCM and may help guide therapeutic LV restoration.

Decreased left ventricular torsion and untwisting in children with dilated cardiomyopathy

The purpose of this study was to analyze left ventricular (LV) torsion and untwisting, and to evaluate the correlation between torsion and other components of LV contraction in children with dilated cardiomyopathy (DCM). Segmental and global rotation, rotational rate (Vrot) were measured at three levels of LV using the two dimensional (2D) speckle tracking imaging (STI) method in 10 DCM patients (range 0.6-15 yr, median 6.5 yr, 3 females) and 17 age- and sex-matched normal controls. Global torsion was decreased in DCM (peak global torsion; 10.9 +/- 4.6 degrees vs. 0.3 +/- 2.1 degrees , p<0.001). Loss of LV torsion occurred mainly by the diminution of counterclockwise apical rotation and was augmented by somewhat less reduction in clockwise basal rotation. In DCM, the normal counterclockwise apical rotation was not observed, and the apical rotation about the central axis was clockwise or slightly counterclockwise (peak apical rotation; 5.9 +/- 4.1 degrees vs. -0.9 +/- 3.1 degrees , p<0.001). Systolic counterclockwise Vrot and early diastolic clockwise Vrot at the apical level were decreased or abolished. In DCM, decreased systolic torsion and loss of early diastolic recoil contribute to LV systolic and diastolic dysfunction. The STI method may facilitate the serial evaluation of the LV torsional behavior in clinical settings and give new biomechanical concepts for better management of patients with DCM.

Does Myocardial Fibrosis Hinder Contractile Function and Perfusion in Idiopathic Dilated Cardiomyopathy? PET and MR Imaging Study

PURPOSE

To prospectively evaluate, by using positron emission tomography (PET) and magnetic resonance (MR) imaging, the interrelationships between regional myocardial fibrosis, perfusion, and contractile function in patients with idiopathic dilated cardiomyopathy (DCM).

MATERIALS AND METHODS

The study protocol was approved by the hospital ethics committee, and all subjects gave written informed consent. Sixteen patients with idiopathic DCM (mean age, 54 years +/- 11 [standard deviation]; nine men) and six healthy control subjects (mean age, 28 years +/- 2; five men) were examined with PET and MR tissue tagging. Oxygen 15-labeled water and carbon monoxide were used as tracers at PET to assess myocardial blood flow (MBF) and the perfusable tissue index (PTI), which is inversely related to fibrosis. MBF was determined at rest and during pharmacologically induced hyperemia. Maximum circumferential shortening (E(cc)) was determined with MR tissue tagging. Student t tests were performed for comparison of data sets, and linear regression was used to investigate the association between parameters.

RESULTS

Mean global hyperemic MBF (2.23 mL/min/mL +/- 0.73), E(cc) (-10.5% +/- 2.9), and PTI (0.95 +/- 0.10) were lower in the patients with DCM than in the control subjects (4.33 mL/min/mL +/- 0.85, -17.4% +/- 0.6, and 1.09 +/- 0.12, respectively; P < .05 for all). In the patients with DCM, regional PTI was related to E(cc) (r = -0.21, P = .009) but not to resting or hyperemic MBF. Furthermore, regional E(cc) was correlated to both resting (r = -0.28, P = .004) and hyperemic MBF (r = -0.29, P < .001). In addition, the ratio of left ventricular end-diastolic volume to mass, as a reflection of wall stress, was related to global hyperemic MBF (r = -0.52, P = .047) and to global E(cc) (r = 0.69, P = .003).

CONCLUSION

In idiopathic DCM, the extent of myocardial fibrosis is related to the impairment in contractile function, whereas fibrosis and perfusion do not seem to be interrelated. The degree of impairment of hyperemic myocardial perfusion is related to contractility and end-diastolic wall stress.

Semiquantitative histomorphometric analysis of myocardium following partial left ventriculectomy: 1-year follow-up

BACKGROUND

Although partial left ventriculectomy (PLV) may have beneficial clinical effects in patients with dilated cardiomyopathy (DCM), there are no reports on effects of PLV on myocardial histology. The objective of this study was to assess histological properties of the LV myocardium 1 year following PLV as compared to histology at the time of the operation.

METHODS

The study group consisted of 15 consecutive PLV survivors, predominantly male (13/15), aged 45+/-12 years. Surgical specimens and endomyocardial biopsies, taken 12 months postoperatively, were processed routinely and stained with Masson-trichrome. The following morphometric parameters were assessed semiquantitavely: (1) degree of hypertrophy and attenuation; (2) nuclear evidence of hypertrophy; (3) myofibrillar volume fraction; (4) degree of degenerative vacuolar changes; and (5) fibrosis volume fraction.

RESULTS

Both New York Heart Association (NYHA) functional class and ejection fraction (EF) improved 12 months following surgery as compared to preoperative values (2.40+/-0.69 vs. 3.33+/-0.49, p<0.001, and 33.21+/-12.05% vs. 20.21+/-9.07%, p<0.001, respectively). Morphometric analysis demonstrated postoperative decrease in the degree of attenuation as compared to preoperative values (1.40+/-0.51 vs. 2.47+/-0.64, p<0.01), as well as a decrease in fibrosis volume fraction (2.07+/-0.80 vs. 2.67+/-0.49, p<0.001) and nuclear hypertrophy (1.27+/-0.46 vs. 1.67+/-0.62, p<0.05). On the other hand, postoperative increase in myofibrillar volume fraction (1.87+/-0.61 vs. 1.40+/-0.61, p<0.01) was noted.

CONCLUSION

One year postoperatively, PLV has favourable effects on myocardial morphology that parallels improvement in the patient's functional status and LV systolic function.

Prognostic significance of morphometric endomyocardial biopsy analysis in patients with idiopathic dilated cardiomyopathy

BACKGROUND

To date, considerable controversy exists on the prognostic significance of morphometric endomyocardial biopsy findings in patients with idiopathic dilated cardiomyopathy (IDC).

METHODS

Quantitative analyses of interstitial structured tissue, myofibril volume fraction, and myocytic fiber diameters of left ventricular endomyocardial biopsy specimens were performed in 124 patients with IDC.

RESULTS

During 51 +/- 22 months follow-up after left ventricular endomyocardial biopsy, major arrhythmic events, defined as sustained ventricular tachycardia (VT), ventricular fibrillation (VF), or sudden cardiac death, were observed in 24 patients (19%). Death from any cause or heart transplant was observed in 39 patients (31%). The amount of interstitial structured tissue, myofibril volume fraction, and myocytic fiber diameters determined from left ventricular endomyocardial biopsy specimens did not differ significantly between patients with and patients without major arrhythmic events or between patients with and patients without transplant-free survival during follow-up.

CONCLUSIONS

Quantitative analysis of the amount of interstitial structured tissue, myofibril volume fraction, and myocytic fiber diameters in left ventricular endomyocardial biopsy specimens does not appear to be useful for predicting arrhythmic events and transplant-free survival in IDC.

Myocardial fibrosis assessment by semiquantitative, point-counting and computer-based methods in patients with heart muscle disease: a comparative study

AIMS

No study has directly compared different histomorphometric methods of quantification of myocardial fibrosis. Therefore we compared the results of semiquantitative, point-counting and computer-based methods in the assessement of myocardial fibrosis in a consecutive series of endomyocardial biopsy samples from patients with heart muscle disease.

METHODS AND RESULTS

Histological samples (at least three per patient) were obtained by endomyocardial biopsy from 11 patients with focal myocarditis and from 24 ambulatory patients with idiopathic dilated cardiomyopathy, or during surgery in 10 patients who underwent partial left ventriculectomy. Samples were cut and stained with Masson-trichrome for better contrast. From each sample, a representative field was digitized, and the amount of fibrosis was assessed by semiquantitative scoring, by point-counting, and by computer-based software. Semiquantitative scoring correlated with both point-counting (Spearman's r = 0.69, P < 0.0001) and computer-based (Spearman's r = 0.83, P < 0.0001) methods. There was also a good correlation between point-counting and computer-based methods (r = 0.71, P < 0.0001). However, when compared with the point-counting method, the computer-based method overestimated percent fibrosis by 3.0 +/- 6.7% (P = 0.004). This overestimation correlated with the mean percent fibrosis (r = 0.38, P = 0.014).

CONCLUSIONS

Our data show good correlations between the three methods of myocardial fibrosis assessment. However, systematic differences between them emphasize that this should be taken into consideration when comparing results of the studies using different methods of fibrosis assessment.

Changes in myocardial cytoskeletal intermediate filaments and myocyte contractile dysfunction in dilated cardiomyopathy: an in vivo study in humans

AIM

To investigate in vivo the intermediate cytoskeletal filaments desmin and vimentin in myocardial tissues from patients with dilated cardiomyopathy, and to determine whether alterations in these proteins are associated with impaired contractility.

METHODS

Endomyocardial biopsies were performed in 12 patients with dilated cardiomyopathy and in 12 controls (six women with breast cancer before anthracycline chemotherapy and six male donors for heart transplantation). Biopsy specimens were analysed by light microscopy and immunochemistry (desmin, vimentin). Myocyte contractile protein function was evaluated by the actin-myosin in vitro motility assay. Left ventricular ejection fraction was assessed by echocardiography and radionuclide ventriculography.

RESULTS

Patients with dilated cardiomyopathy had a greater cardiomyocyte diameter than controls (p < 0.01). The increase in cell size was associated with a reduction in contractile function, as assessed by actin-myosin motility (r = -0.643; p < 0.01). Quantitative immunochemistry showed increased desmin and vimentin contents (p < 0.01), and the desmin distribution was disturbed in cardiomyopathy. There was a linear relation between desmin distribution and actin-myosin sliding in vitro (r = 0.853; p < 0.01) and an inverse correlation between desmin content and ejection fraction (r = -0.773; p < 0.02). Negative correlations were also found between myocardial vimentin content and the actin-myosin sliding rate (r = -0.74; p < 0.02) and left ventricular ejection fraction (r = -0.68; p < 0.01).

CONCLUSIONS

Compared with normal individuals, the myocardial tissue of patients with dilated cardiomyopathy shows alterations of cytoskeletal intermediate filament distribution and content associated with reduced myocyte contraction.

Diffuse and severe left ventricular dysfunction induced by epicardial coronary artery spasm

Endothelial dysfunction and effectiveness of treatment of calcium antagonists are suggestive of coronary artery spasm as an underlying disorder in dilated cardiomyopathy (DCM). The aim of this study is to determine whether or not the epicardial coronary artery spasm can induce severe cardiac dysfunction like DCM. Thirty-four consecutive patients with angiographically normal coronary arteries and diffuse left ventricular hypokinesis whose causes had been unknown underwent acetylcholine provocation test and left ventricular biopsy. Eight patients were excluded according to the clinical and laboratory data and biopsy findings suggesting myocarditis or other systemic diseases. According to the results of the acetylcholine provocation test, 17 patients were finally diagnosed as having DCM, and nine patients (35% of the study patients), who had acetylcholine-induced diffuse and multivessel coronary spasm, were diagnosed as having DCM-like vasospastic angina pectoris (VSA). Clinical and cardiac catheterization data including hemodynamics and biopsy findings were similar between the two groups except that left ventricular end-systolic volume was significantly greater in DCM than in DCM-like VSA. After the acetylcholine provocation test, DCM patients received both a beta blocker and an angiotensin-converting enzyme inhibitor, and DCM-like VSA patients received antianginal drugs. In echocardiographic findings at predischarge and those after 6-month drug treatment, both DCM-lke VSA and DCM showed significant reduction in end-diastolic and end-systolic diameters and significant increase in fractional shortening and ejection fraction, whereas changes in ejection fraction and fractional shortening were significantly greater in DCM-like VSA than those in DCM. Epicardial coronary artery spasm can induce diffuse and severe left ventricular dysfunction like DCM in VSA. Although antianginal drugs markedly improve left ventricular function of these patients, only the acetylcholine provocation test can identify DCM-like VSA.

Myofibrillar protein structure and assembly during idiopathic dilated cardiomyopathy

A neutral protease, mekratin, active in human hearts at end stage idiopathic dilated cardiomyopathy (IDC), mediates the breakdown of cardiac myosin LC2. Myosin purified from IDC heart tissue forms unusually short synthetic thick filaments. Therefore, determination of filament length and mekratin distribution in IDC heart muscle were initiated. Native thick filaments were prepared directly from control and IDC tissues and analyzed. Also, paraffin-embedded tissue sections were stained with a fluorescently-labeled anti-protease antibody to establish its distribution in myocardial tissues. Control sections had only very weak, background levels of fluorescence whereas IDC sections stained intensely throughout, indicating a wide ranging distribution of the protease within the myocyte cytoplasm. SDS-PAGE revealed LC2 to be present in stoichiometric amounts in control but greatly reduced in IDC heart muscle. Native thick filaments from control myocardium were structurally stable. They had a median length of 1.65 microm with well-defined bare zones and displayed the 43 nm helical periodicity typical of the relaxed arrangement of myosin heads close to the filaments' shafts. In contrast, native IDC filaments were less stable, and had a median length of 0.9 microm. These filaments were highly disordered: they had no surface periodicity and myosin heads were positioned away from the filaments' shafts. The shorter, less stable, aperiodic thick filaments from IDC hearts appear to result from depletion of LC2 caused by increased activity of mekratin in the IDC myocardium.

Assessment of myocardial fatty acid metabolic abnormalities in patients with idiopathic dilated cardiomyopathy using 123I BMIPP SPECT: correlation with clinicopathological findings and clinical course

OBJECTIVE

To determine the clinical and prognostic value of identifying metabolic abnormalities of myocardial fatty acid metabolism in idiopathic dilated cardiomyopathy using iodine-123 beta-methyl-iodophenyl pentadecanoic acid (123I BMIPP).

SETTING

Cardiac care division in national hospital.

PATIENTS

32 consecutive patients with idiopathic dilated cardiomyopathy in whom both 123I BMIPP and thallium-201 myocardial single photon emission computed tomography were performed.

METHODS

The uptake of each tracer was scored visually from 0 (normal) to 3 (defect) in 17 segments (eight basal, eight midventricular, and one apical). A total score for all 17 segments was compared with clinicopathological variables. Prognostic value of mismatches between the two tracers were also evaluated.

RESULTS

The 123I BMIPP total score was correlated with pulmonary capillary wedge pressure (r = 0.68, p < 0.001), left ventricular end diastolic pressure (r = 0.65, p < 0.001), percentage fractional shortening at six months' follow up (r = -0.58, p = 0. 001), myocyte diameter (r = 0.66, p < 0.001), and percentage area of interstitial fibrosis (r = 0.69, p < 0.001) measured by morphometry in the biopsy specimens. During a mean (SD) follow up of 20 (11) months, deterioration of the New York Heart Association functional class was observed in 11 of the 32 patients; four of these died. Segments with a greater decrease in 123I BMIPP than thallium-201 uptake (type B mismatching) were often observed in patients with deterioration (88/187, 29% v 58/357, 16%; p < 0.001).

CONCLUSIONS

The extent of the abnormality of myocardial fatty acid metabolism in idiopathic dilated cardiomyopathy reflects the severity of haemodynamic deterioration and histopathological changes. Type B mismatching is one of the important prognostic indicators in idiopathic dilated cardiomyopathy.

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.

Comparative study of 201Tl-scintigraphic image and myocardial pathologic findings in patients with dilated cardiomyopathy

The objective of the present study was to characterize the production of 201Tl myocardial perfusion defects, the relation between the 201Tl multiple small defects and the myocardial damage indicated by myocardial fibrosis shown histopathologically in patients with dilated cardiomyopathy (DCM). Rest 201Tl scintigraphy was performed in thirty-seven patients with myocardial tissue fibrosis by endomyocardial biopsy, and without stenosis of the coronary artery. 201Tl myocardial SPECT images were visually classified into 4 grades according to the severity of inhomogeneous perfusion defects (IPD), 0: none, 1: slight, 2: moderate, 3: severe. 201Tl uptake, defect regions (DR), and coefficient of variation % (CV%) were also quantified by Bull's eye quantification in nineteen patients. During cardiac catheterization, three biopsy specimens were obtained from the lateral wall to the apical region of the left ventricle and the amount of fibrosis was assessed by means of light microscopic morphometry. The myocardial fibrosis was also classified into 4 grades by a point-counting method. Autopsy study was also assessed in six patients. 201Tl perfusion defects were observed in 35 (94.6%) patients, of whom 29 (78.4%) showed inhomogeneous perfusion defects. Twenty-four (64.9%) showed Stage 0 and 201Tl findings, and 21 (62.2%) had myocardial fibrosis in stage 1. Clinically, the correlation between the grades of the IPD, % 201Tl uptake, DR and CV% of myocardial uptake, which were calculated semiquantitatively by Bull's eye image, and the histological grades of fibrosis were also good (IPD vs. fibrosis: r = 0.7014; % 201Tl uptake vs. fibrosis: r = -0.6542; DR vs. fibrosis: r = 0.7027; CV% vs. fibrosis: r = 0.6985). The 201Tl SPECT findings were in close agreement with the severity of myocardial fibrosis confirmed by autopsy, but the grading of the IPD was not related to the ejection fraction or left ventricular diameter. It showed a higher rate of inhomogeneous 201Tl myocardial perfusion defects (78.4%) in patients with DCM. This result may contribute to the clinical evaluation of DCM or differentiation from other diseases. Furthermore, the grading of 201Tl inhomogeneous perfusion defects related to the myocardial fibrosis of left ventricular myocardium may contribute to speculation of the myocardial degenerative stage in clinical settings.

Heterogeneity of ventricular function and myocardial oxidative metabolism in nonischemic dilated cardiomyopathy

OBJECTIVES

This study was performed to test the hypothesis that regional variation in ventricular function in patients with nonischemic dilated cardiomyopathy is related to regional variation in oxidative metabolism.

BACKGROUND

Heterogeneity in regional left ventricular function has long been noted in patients with nonischemic dilated cardiomyopathy. Regional variation in wall stress has been proposed as the pathophysiologic mechanism. By correlating regional function with oxidative metabolism, one can test the hypothesis that heterogeneity in wall stress is responsible for heterogeneity in function. We hypothesized that preserved function as a result of more favorable loading conditions would be associated with regional oxidative metabolism that is equal to or lower than that in other regions.

METHODS

Fifteen patients with nonischemic dilated cardiomyopathy (mean [+/- SD] ejection fraction 20.7 +/- 4.0%) were studied. Regional ventricular function was determined using short-axis chordal shortening on two-dimensional echocardiography. Regional oxidative metabolism was assessed by carbon-11 acetate clearance kinetics on dynamic positron emission tomography. An eight-segment model of the left ventricle was used. Segmental function and oxidative metabolism were defined as increased if they varied at least 1 SD from the respective mean value for that patient.

RESULTS

Thirteen (87%) of 15 patients exhibited segments with increased function. In 7 (54%) of 13 patients, regional function was increased in the proximal lateral wall. Multivariate linear regression analysis showed a direct relation between regional function and oxidative metabolism (p = 0.02). The average concordance between increased function and increased oxidative metabolism among patients was 0.87 +/- 0.11 (95% confidence interval 0.70 to 1.00).

CONCLUSIONS

Patients with nonischemic dilated cardiomyopathy display heterogeneity in regional ventricular function. Relative preservation is observed most frequently in the proximal lateral wall. Relative preservation of function is associated with higher regional oxidative metabolism, suggesting that mechanisms other than or in addition to local loading conditions may be responsible for heterogeneity in function.

Nature of ventricular activation in patients with dilated cardiomyopathy: evidence for bilateral bundle branch block

OBJECTIVE

To investigate the nature of ventricular activation and its relation with mechanical events in patients with dilated cardiomyopathy.

STUDY DESIGN

Retrospective and prospective study with 12 lead electrocardiograms, signal averaged electrocardiograms, and M mode and Doppler echocardiograms.

SETTING

Tertiary cardiac referral centre.

PATIENTS

77 patients (mean (SD) age 59(13)) with dilated cardiomyopathy, four after aortic valve replacement and three after coronary bypass surgery, and six patients with a normal sized left ventricle and complete right bundle branch block were studied. 15 normal subjects (age 45(20)) were used as controls.

RESULTS

In patients with dilated cardiomyopathy, QRS duration was longer (127(25) ms v 90(10), P < 0.05) than normal and was normally distributed (r = 0.991, P < 0.01) on a normal probability plot. 20 had classic left bundle branch block, 29 intraventricular conduction delay, four right bundle branch block, and one bifascicular block. The PR interval was prolonged (185(30) ms v 150(15), P < 0.05). Electromechanical delay, Q to the onset of thickening of the interventricular septum as seen on the transverse M mode echocardiogram, was 75(15) ms in controls, but reduced to 43(15) ms in the patients (P < 0.01). Q to the onset of mitral regurgitation was also short (50(15)) ms, and correlated inversely with PR interval (r = -0.67, n = 73, P < 0.01). Early potentials (< 40 microV) were recorded on the signal averaged electrocardiogram in 33 representative patients and in all controls. Their overall duration was 30(12) ms in the patients, much longer than normal (12(7), P < 0.01)). Early potential time correlated positively with PR interval (r = 0.75, P < 0.01) and QRS duration (r = 0.60, P < 0.01) on a 12 lead electrocardiogram, and negatively with apparent electromechanical delay (r = -0.71, P < 0.01, n = 33), but not with true electromechanical delay (73(15)ms) or true PR interval (163(30)ms), calculated by correcting apparent values for early potential. The onset of left ventricular free wall motion was delayed with respect to the septum beyond 95% of the upper normal limit in all the patients with classic left bundle branch block and intraventricular conduction defect. Motion in the right ventricular free wall was delayed in 13 of 20 patients with left bundle branch block and 24 of 29 with intraventricular conduction defect by 65(20) ms, similar to that (75(10) ms) in patients with right bundle branch block.

CONCLUSION

In most patients with dilated cardiomyopathy and an electrocardiographic pattern of left bundle branch block or intraventricular block, the onset of mechanical systole is strikingly and symmetrically delayed in both ventricles, compatible with bilateral bundle branch block. Complete atrioventricular block does not occur. The ventricle is activated through the upper septum and this activation is detectable only by signal averaged electrocardiography. The anatomical substrates for this abnormal activation could be the high connections described by Mahaim and Winston.

New approach to the estimation of the extent of myocardial fibrosis in patients with dilated cardiomyopathy: use of signal-averaged electrocardiography

To determine whether the extent of myocardial fibrosis in dilated cardiomyopathy could be estimated noninvasively, signal-averaged electrocardiograms were recorded in 32 patients with dilated cardiomyopathy, followed by left ventricular endomyocardial biopsy. The root mean square voltage for the last 40 msec (V40), the duration of the filtered QRS complex (fQRSd) and the duration of low amplitude signals < 40 microV (LAS) were obtained by signal-averaged electrocardiography. The extent of fibrosis in all biopsy samples was measured by the point-counting method. The extent of myocardial fibrosis closely correlated with fQRSd (r = 0.623, p < 0.001), LAS (r = 0.570, p < 0.001), and V40 (r = -0.355, p < 0.05). When fibrosis was classified into intercellular and interfascicular types, the extent of intercellular fibrosis more closely correlated with fQRSd (r = 0.695, p < 0.0001), LAS (r = 0.640, p < 0.0001), and V40 (r = -0.533, p < 0.005). These results suggest that signal-averaged electrocardiograms might be useful for estimation of the extent of myocardial fibrosis, especially intercellular fibrosis in patients with dilated cardiomyopathy.

Clinical and histologic features of alcohol drinkers with congestive heart failure

To clarify the difference between alcoholic cardiomyopathy and dilated cardiomyopathy and to investigate the characteristics of alcoholic cardiomyopathy, right ventricular endomyocardial biopsy was performed, and the two diseases were compared clinically and histologically. Changes in the cardiothoracic ratio, cardiac index, and systolic blood pressure/end-systolic volume index were greater after treatment in patients with alcoholic cardiomyopathy than in patients with dilated cardiomyopathy. Histologically, myocytic hypertrophy, fibrosis, and nuclear change were less significant in the former than in the latter. Among patients with alcoholic cardiomyopathy, the cardiac index in those with less fibrosis was greater than in those with more fibrosis. Thus patients with alcoholic cardiomyopathy had more preserved and reversible cardiac function and fewer histologic changes than the patients with dilated cardiomyopathy. Reversibility of cardiac function in patients with alcoholic cardiomyopathy correlated inversely with the severity of histologic changes.

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.

Alterations in left ventricular diastolic function in conscious dogs with pacing-induced heart failure

We investigated in conscious dogs (a) the effects of heart failure induced by chronic rapid ventricular pacing on the sequence of development of left ventricular (LV) diastolic versus systolic dysfunction and (b) whether the changes were load dependent or secondary to alterations in structure. LV systolic and diastolic dysfunction were evident within 24 h after initiation of pacing and occurred in parallel over 3 wk. LV systolic function was reduced at 3 wk, i.e., peak LV dP/dt fell by -1,327 +/- 105 mmHg/s and ejection fraction by -22 +/- 2%. LV diastolic dysfunction also progressed over 3 wk of pacing, i.e., tau increased by +14.0 +/- 2.8 ms and the myocardial stiffness constant by +6.5 +/- 1.4, whereas LV chamber stiffness did not change. These alterations were associated with increases in LV end-systolic (+28.6 +/- 5.7 g/cm2) and LV end-diastolic stresses (+40.4 +/- 5.3 g/cm2). When stresses and heart rate were matched at the same levels in the control and failure states, the increases in tau and myocardial stiffness were no longer observed, whereas LV systolic function remained depressed. There were no increases in connective tissue content in heart failure. Thus, pacing-induced heart failure in conscious dogs is characterized by major alterations in diastolic function which are reversible with normalization of increased loading condition.

Prognostic value of thallium-201 perfusion defects in idiopathic dilated cardiomyopathy

To assess the prognostic significance of thallium-201 perfusion defects in patients with idiopathic dilated cardiomyopathy (IDC), 43 patients underwent thallium scintigraphy in addition to clinical, echocardiographic, angiographic and hemodynamic evaluation. Eleven patients had no significant thallium perfusion abnormality, 19 had multiple small defects and 13 had a large defect. During 3.2 +/- 2.2 years, 14 patients had disease-related mortality. The patients who died had a higher incidence of ventricular tachycardia (71 vs 31%; p less than 0.02), increased cardiothoracic ratio (60 +/- 6 vs 54 +/- 6; p = 0.005), decreased fractional shortening (11 +/- 6 vs 15 +/- 5; p less than 0.05), increased pulmonary wedge pressure (15 +/- 7 vs 10 +/- 6 mm Hg; p = 0.05), increased left ventricular end-diastolic pressure (21 +/- 8 vs 14 +/- 6 mm Hg; p = 0.02) and abnormal thallium perfusion defects (13 of 14 vs 16 of 26; p less than 0.05) compared with survivors. Age, gender, left ventricular end-systolic and end-diastolic dimensions, cardiac index and ejection fraction were not statistically different in the survivors versus the patients who died. Kaplan-Meier survival estimates at 1, 3 and 5 years were 100% in patients without significant perfusion abnormality; 89, 77 and 64%, respectively, in patients with multiple small defects; and 84, 76 and 30%, respectively, in patients with a large defect (p less than 0.025 by log rank test).(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular regional wall stress in dilated cardiomyopathy

Left ventriculography with simultaneous pressure micromanometry was performed in 11 normal control subjects and 17 patients with dilated cardiomyopathy (DCM). Left ventricular silhouettes in the right anterior oblique projection were divided into eight areas, and regional wall stress was computed by Janz's method in each area excluding the two most basal areas. Wall stress was higher in DCM patients than in control subjects (p less than 0.01). The percent area changes from end diastole to end systole in each area were lower in DCM patients than in control subjects (mean for six areas, 22 +/- 14% versus 54 +/- 9%, respectively, p less than 0.01), but the coefficient of variation for the percent area changes in the six areas of the left ventricle in DCM patients was greater than that in control subjects (32 +/- 17% versus 15 +/- 4%, respectively, p less than 0.01), indicating regional differences in hypokinesis. There was a significant negative correlation between end-systolic regional wall stress and percent area change (r = -0.60 to -0.86, p less than 0.05) in each area. Thus, excessive regional afterload may play an important role in causing regional hypokinesis in DCM.

Mildly dilated congestive cardiomyopathy. Use of prospective diagnostic criteria and description of the clinical course without heart transplantation

Prognosis in classically described dilated congestive cardiomyopathy has been reported to be related to ventricular size. Mildly dilated congestive cardiomyopathy (MDCM) has been defined as end-stage heart failure of unknown etiology (New York Heart Association class IV, left ventricular ejection fraction less than 30%), occurring with neither typical hemodynamic signs of restrictive myopathy nor significant ventricular dilatation (less than 15% above normal range). The present study includes follow-up in 12 nontransplant patients. In the first 4 months after diagnosis, two patients improved and are living, and two showed cardiac dilation and clinical deterioration and died. Six of the remaining eight with persistent MDCM died (four with intractable heart failure and two, sudden deaths) without change in ventricular size before death, despite medical therapy over 20 +/- 8 months. Eight comparable transplanted patients with persistent MDCM demonstrated improved total survival by life table analysis (p less than 0.05). A family history of congestive cardiomyopathy was found in nine of 16 patients (56%) with persistent MDCM. Nontransplant patients were older (p less than 0.02), but other findings were similar in the two groups. Endomyocardial biopsies available in 14 of 16 cases showed little or no myofibrillar loss in spite of severe hemodynamic impairment. The degree of myofibrillar loss did not correlate with hemodynamic parameters but showed good correlation with left ventricular size, that is, five of six patients with no myofibrillar loss had normal ventricular size, whereas all eight patients with mild myofibrillar loss had mild cardiomegaly (p less than 0.002). Our current experience suggests a somewhat variable but negative prognosis after prospective diagnosis of MDCM, with poor survival in patients with persistence of the original diagnostic features during follow-up. Preservation of heart size in MDCM is probably related to lack of significant myofibrillar loss. Thus, irrespective of heart size or myofibrillar preservation on biopsy, heart transplantation should be strongly considered in MDCM if signs of severe cardiac dysfunction persist despite therapy.

Functional and structural abnormalities in patients with dilated cardiomyopathy

Passive diastolic properties of the left ventricle were determined in 10 control subjects and 12 patients with dilated cardiomyopathy. Simultaneous left ventricular angiography and high fidelity pressure measurements were performed in all patients. Left ventricular chamber stiffness was calculated from left ventricular pressure-volume and myocardial stiffness from left ventricular stress-strain relations with use of a viscoelastic model. Patients with dilated cardiomyopathy were classified into two groups according to the diastolic constant of myocardial stiffness (beta). Group 1 consisted of seven patients with a normal constant of myocardial stiffness less than or equal to 9.6 (normal range 2.2 to 9.6) and group 2 of 5 patients with a beta greater than 9.6. Structural abnormalities (percent interstitial fibrosis, fibrous content) in patients with dilated cardiomyopathy were assessed by morphometry from right ventricular endomyocardial biopsies. Heart rate was similar in the three groups. Left ventricular end-diastolic pressure was significantly greater in patients with cardiomyopathy (18 mm Hg in group 1 and 22 mm Hg in group 2) than in the control patients (10 mm Hg). Left ventricular ejection fraction was significantly lower in groups 1 (37%) and 2 (36%) than in the control patients (66%). Left ventricular muscle mass index was significantly increased in both groups with cardiomyopathy. The constant of chamber stiffness (beta*) was slightly although not significantly greater in groups 1 and 2 (0.58 and 0.58, respectively) than in the control group (0.35). The constant of myocardial stiffness beta was normal in group 1 (7.0; control group 6.9, p = NS) but was significantly increased in group 2 (23.5). Interstitial fibrosis was 19% in group 1 and 43% (p less than 0.001) in group 2 (normal less than or equal to 10%). There was an exponential relation between both diastolic constant of myocardial stiffness (beta) and interstitial fibrosis (IF) (r = 0.95; p less than 0.001) and beta and fibrous content divided by end-diastolic volume index (r = 0.93; p less than 0.001). It is concluded that myocardial stiffness can be normal in patients with dilated cardiomyopathy despite severely depressed systolic function. Structural alterations of the myocardium with increased amounts of fibrous tissues are probably responsible for the observed changes in passive elastic properties of the myocardium in patients with dilated cardiomyopathy. The constant of myocardial stiffness (beta) helps to identify patients with severe structural alterations (group 2), representing possibly a more advanced stage of the disease.

The challenge of cardiomyopathy

The combined clinical and pathophysiologic characteristics and diagnostic features as well as current concepts of pathogenesis, therapy and prevention of the principal forms of cardiomyopathy are reviewed. These include hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy and specific cardiac muscle disease. Emphasis is placed on recent developments and unresolved questions requiring application of newer techniques of molecular biology and genetics and adult myocyte culturing.