Prospective study of everolimus with calcineurin inhibitor-free immunosuppression after heart transplantation: results at four years.

BACKGROUND: Immunosuppression is necessary after transplantation but it is associated with distinct adverse side effects. These negative effects could at least partially be overcome with the mammalian target of Rapamycin (mTOR) inhibitor everolimus. Few studies have examined everolimus therapy with calcineurin inhibitor (CNI) withdrawal in maintenance heart transplant patients (HTx). METHODS: In this prospective, single-arm, single-center study, maintenance patients after HTx were converted from CNI to everolimus. They were followed for 48 months. Primary endpoints were kidney-function and arterial hypertension. RESULTS: Forty-eight patients were recruited (mean post-transplant time 5.4 ± 3.5 years). Of these, 36 were followed for the entire 4-year period. Median calculated glomerular filtration rate increased from 40.7 (32.4 to 59.1) mL/minute at baseline to 48.9 (29.7 to 67)) mL/minute at month 48 (p = not significant). Median systolic and diastolic blood pressure, triglycerides, and high-density lipoprotein and low-density lipoprotein cholesterol, did not change significantly in a comparison of the values at baseline and at 48 months. Early resolution of most non-renal CNI-related adverse events was sustained. Due to adverse events, CNI therapy had to be reintroduced in 6 patients (12.5%). No significant changes in cardiac function parameters were observed. CONCLUSIONS: Calcineurin inhibitor-free immunosuppression with everolimus is an effective and safe option in selected maintenance HTx patients. Most adverse effects under everolimus occurred early after conversion and in most cases resolved without intervention within a few weeks. Refining selection criteria may help both in identifying patients who will profit most from switching and in alleviating the need to reintroduce CNI therapy.

Heterogeneous Connexin43 distribution in heart failure is associated with dispersed conduction and enhanced susceptibility to ventricular arrhythmias.

AIMS: Sudden arrhythmogenic cardiac death is a major cause of mortality in patients with congestive heart failure (CHF). To investigate determinants of the increased arrhythmogenic susceptibility, we studied cardiac remodelling and arrhythmogenicity in CHF patients and in a mouse model of chronic pressure overload. METHODS AND RESULTS: Clinical and (immuno)histological data of myocardial biopsies from CHF patients with (VT+) and without (VT-) documented ventricular arrhythmia were compared with controls. In CHF patients, ejection fraction was decreased and QRS duration was increased. Cell size and interstitial fibrosis were increased, but Connexin43 (Cx43) levels, the most abundant gap junction in ventricular myocardium, were unchanged. No differences were found between VT+ and VT- patients, except for the distribution pattern of Cx43, which was significantly more heterogeneous in VT+. Mice were subjected to transverse aortic constriction (TAC) or sham operated. At 16 weeks, cardiac function was determined by echocardiography and epicardial ventricular activation mapping was performed. Transverse aortic constriction mice had decreased fractional shortening and prolonged QRS duration. Right ventricular conduction velocity was reduced, and polymorphic VTs were induced in 44% TAC and 0% sham mice. Interstitial fibrosis was increased and Cx43 quantity was unchanged in TAC mice with and without arrhythmias. Similar to CHF patients, heterogeneous Cx43 distribution was significantly associated with arrhythmias in TAC mice and with spatial heterogeneity of impulse conduction. CONCLUSION: Heterogeneous Cx43 expression during CHF is associated with dispersed impulse conduction and may underlie enhanced susceptibility to ventricular tachyarrhythmias.

Reduced repolarization reserve due to anthracycline therapy facilitates torsade de pointes induced by IKr blockers.

BACKGROUND: Cytostatic agents such as anthracyclines may cause changes in the electrophysiologic properties of the heart. We hypothesized that anthracyclines facilitate life-threatening proarrhythmic side effects of cardiovascular and non-cardiovascular repolarization prolonging drugs. METHODS AND RESULTS: The electrophysiologic effects of chronic administration of doxorubicin (Dox) were studied in ten rabbits, which were treated with Dox twice a week (1.5 mg/kg i.v.). A control group (11 rabbits) was given NaCl solution. Two of ten Dox rabbits died suddenly, the remaining animals showed mild clinical signs of heart failure after a period of six weeks. Echocardiography demonstrated a decrease in ejection fraction (pre treatment: 74 +/- 23% to post treatment: 63 +/- 16% (p <0.05)). In isolated hearts, action potential duration measured by eight simultaneously recorded monophasic action potentials (MAP) was similar in Dox and control hearts. However, in Dox rabbits, administration of the I(Kr)-blocker erythromycin (150-300 microM) led to a significant greater prolongation of the mean MAP duration (63 +/- 21ms vs 29 +/- 12 ms, p <0.05) and the QT interval (100 +/- 32ms vs 58 +/- 17 ms, p <0.05) as compared to control. Moreover, I(Kr)-block led to a more marked increase of dispersion of MAP(90) in the Dox group as compared to control hearts (23 +/- 7ms vs. 9 +/- 4 ms). In the presence of hypokalemia more episodes of early afterdepolarizations and torsade de pointes occurred (p <0.05). CONCLUSION: Even during the early phase of chemotherapeutic treatment,before significant QT-prolongation is present,anthracyclines lead to an increased sensitivity to the proarrhythmic potency of I(Kr)-blocking drugs. Thus, anthracycline therapy reduces repolarization reserve and thereby represents a novel contributing factor for the development of life-threatening proarrhythmia.

Lysosomal, cytoskeletal, and metabolic alterations in cardiomyopathy of cathepsin L knockout mice.

Although lysosomal proteases are expressed in the heart at considerable levels, their specific functions in this organ remain elusive. Mice deficient for the lysosomal cysteine protease cathepsin L (CTSL) develop a late onset dilated cardiomyopathy (DCM) that is characterized by cardiac chamber dilation, fibrosis, and impaired cardiac contraction at 12 month of age. Investigation of the pathogenic sequence of DCM in ctsl-/- mice revealed numerous dysmorphic lysosome-like structures in heart muscle as early as 3 days after birth, whereas skeletal muscle was not affected. Labeling of the acidic cell compartment of neonatal cardiomyocytes and detection of lysosomal markers after subcellular fractionation confirmed increased lysosome content in CTSL deficient myocardium; however, specific storage materials were not detected. The myocardium of ctsl+/+ and ctsl-/- mice revealed no differences in incidence of cell death, proliferation, and capillary density during DCM progression. However, an observed increase in mRNA expression of natriuretic peptides in young adult mice indicates the activation of the adaptive "fetal" gene program, while proteome analysis revealed decreased levels of the sarcomere-associated proteins alpha-tropomyosin, desmin, and calsarcin 1, as well as considerable changes of metabolic enzymes. Bioinformatic pathway analysis suggested a switch to anaerobic catabolism and impairment of mitochondrial respiration. This interpretation was supported by a 50% reduction in resting state oxygen consumption and impaired respiration capacity in ctsl-/- myocardial homogenates. In summary, the data indicate an essential role of CTSL in maintaining the structure of the endosomal/lysosomal compartment in cardiomyocytes. Lysosomal impairment in ctsl-/- hearts results in metabolic and sarcomeric alterations that promote DCM development.

Pericarditis constrictiva and high-degree atrioventricular block as a first manifestation of a cardiac B-cell lymphoma.

Primary cardiac lymphoma is an extremely rare extranodal non-Hodgkin's lymphoma, exclusively located in the heart and/or the pericardium with no evidence of extracardiac dissemination. In this report, we describe a cardiac B-cell lymphoma arising in a 70-year-old woman who presented to the hospital with heart failure symptoms and a high-degree atrioventricular block of unknown origin. Echocardiography revealed a massive infiltrative thickening of the atrial septum, the aortic root, and the pericardium. Pulsed wave and Doppler tissue findings were highly suggestive for pericarditis constrictiva. Positron emission tomography showed unusually strong metabolic activity in the atrial septum, both atria, and the entire pericardium. Suggested malignoma was confirmed by the pericardial biopsy specimens, which revealed a high-grade diffuse CD20+ B-cell lymphoma.