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

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.

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.

An approach to endomyocardial biopsy interpretation

The endomyocardial biopsy (EMB) remains the gold standard mode of investigation for diagnosing many primary and secondary cardiac conditions. Through a percutaneous and transvenous route, tissue fragments are generally procured from the right ventricular septum, with very few complications. Widespread use of EMB followed the development of heart transplantation as a means to follow allograft rejection. It has since been useful in helping to diagnose conditions affecting the heart, including cardiomyopathies, myocarditis, infiltrative lesions, arrhythmias, and drug toxicities. The procedure has also been used as a research tool to investigate the natural history of disease and the cardiotoxicity of new medications. This review presents an approach to the evaluation of the EMB, which is particularly directed towards those who may be asked to interpret such biopsies, but are not dedicated cardiovascular pathologists. Through a systematic evaluation of the endocardium, myocardium, interstitium, and intramural vessels, in the context of a complete clinical history, enough information can be deduced to diagnose or exclude specific conditions of clinical value.