Aims This study investigated the relationship between right ventricular (RV) structure and function and survival in idiopathic pulmonary arterial hypertension (IPAH). Methods and resultsIn 64 patients, cardiac magnetic resonance, right heart catheterization, and the six-minute walk test (6MWT) were performed at baseline and after 1-year follow-up. RV structure and function were analysed as predictors of mortality. During a mean follow-up of 32 months, 19 patients died. A low stroke volume (SV), RV dilatation, and impaired left ventricular (LV) filling independently predicted mortality. In addition, a further decrease in SV, progressive RV dilatation, and further decrease in LV end-diastolic volume (LVEDV) at 1-year follow-up were the strongest predictors of mortality. According to Kaplan-Meier survival curves, survival was lower in patients with an inframedian SV index 25 mL/m 2 , a supramedian RV end-diastolic volume index !84 mL/m 2 , and an inframedian LVEDV 40 mL/m 2 . Conclusions The RV contains prognostic information in IPAH. A large RV volume, low SV, and a reduced LV volume are strong independent predictors of mortality and treatment failure.

Background-To support the clinical distinction between systolic heart failure (SHF) and diastolic heart failure (DHF), left ventricular (LV) myocardial structure and function were compared in LV endomyocardial biopsy samples of patients with systolic and diastolic heart failure. Methods and Results-Patients hospitalized for worsening heart failure were classified as having SHF (nϭ22; LV ejection fraction (EF) 34Ϯ2%) or DHF (nϭ22; LVEF 62Ϯ2%). No patient had coronary artery disease or biopsy evidence of infiltrative or inflammatory myocardial disease. More DHF patients had a history of arterial hypertension and were obese. Biopsy samples were analyzed with histomorphometry and electron microscopy. Single cardiomyocytes were isolated from the samples, stretched to a sarcomere length of 2.2 m to measure passive force (F passive ), and activated with calcium-containing solutions to measure total force. Cardiomyocyte diameter was higher in DHF (20.3Ϯ0.6 versus 15.1Ϯ0.4 m, PϽ0.001), but collagen volume fraction was equally elevated. Myofibrillar density was lower in SHF (36Ϯ2% versus 46Ϯ2%, PϽ0.001). Cardiomyocytes of DHF patients had higher F passive (7.1Ϯ0.6 versus 5.3Ϯ0.3 kN/m 2 ; PϽ0.01), but their total force was comparable. After administration of protein kinase A to the cardiomyocytes, the drop in F passive was larger (PϽ0.01) in DHF than in SHF. Conclusions-LV myocardial structure and function differ in SHF and DHF because of distinct cardiomyocyte abnormalities. These findings support the clinical separation of heart failure patients into SHF and DHF phenotypes.

Background-Heart failure with preserved left ventricular (LV) ejection fraction (EF) is increasingly recognized and usually referred to as diastolic heart failure (DHF). Its pathogenetic mechanism remains unclear, partly because of a lack of myocardial biopsy material. Endomyocardial biopsy samples obtained from DHF patients were therefore analyzed for collagen volume fraction (CVF) and sarcomeric protein composition and compared with control samples. Single cardiomyocytes were isolated from these biopsy samples to assess cellular contractile performance. Methods and Results-DHF patients (nϭ12) had an LVEF of 71Ϯ11%, an LV end-diastolic pressure (LVEDP) of 28Ϯ4 mm Hg, and no significant coronary artery stenoses. DHF patients had higher CVFs (7.5Ϯ4.0%, PϽ0.05) than did controls (nϭ8, 3.8Ϯ2.0%), and no conspicuous changes in sarcomeric protein composition were detected. Cardiomyocytes, mechanically isolated and treated with Triton X-100 to remove all membranes, were stretched to a sarcomere length of 2.

Background-Prominent features of myocardial remodeling in heart failure with preserved ejection fraction (HFPEF) are high cardiomyocyte resting tension (F passive ) and cardiomyocyte hypertrophy. In experimental models, both reacted favorably to raised protein kinase G (PKG) activity. The present study assessed myocardial PKG activity, its downstream effects on cardiomyocyte F passive and cardiomyocyte diameter, and its upstream control by cyclic guanosine monophosphate (cGMP), nitrosative/oxidative stress, and brain natriuretic peptide (BNP). To discern altered control of myocardial remodeling by PKG, HFPEF was compared with aortic stenosis and HF with reduced EF (HFREF). Methods and Results-Patients with HFPEF (nϭ36), AS (nϭ67), and HFREF (nϭ43) were free of coronary artery disease. More HFPEF patients were obese (PϽ0.05) or had diabetes mellitus (PϽ0.05). Left ventricular myocardial biopsies were procured transvascularly in HFPEF and HFREF and perioperatively in aortic stenosis. F passive was measured in cardiomyocytes before and after PKG administration. Myocardial homogenates were used for assessment of PKG activity, cGMP concentration, proBNP-108 expression, and nitrotyrosine expression, a measure of nitrosative/oxidative stress. Additional quantitative immunohistochemical analysis was performed for PKG activity and nitrotyrosine expression. Lower PKG activity in HFPEF than in aortic stenosis (PϽ0.01) or HFREF (PϽ0.001) was associated with higher cardiomyocyte F passive (PϽ0.001) and related to lower cGMP concentration (PϽ0.001) and higher nitrosative/oxidative stress (PϽ0.05). Higher F passive in HFPEF was corrected by in vitro PKG administration. Conclusions-Low myocardial PKG activity in HFPEF was associated with raised cardiomyocyte F passive and was related to increased myocardial nitrosative/oxidative stress. The latter was probably induced by the high prevalence in HFPEF of metabolic comorbidities. Correction of myocardial PKG activity could be a target for specific HFPEF treatment. (Circulation. 2012;126:830-839.)

Abstract-Abnormalities of diastolic function are common to virtually all forms of cardiac failure. However, their underlying mechanisms, precise role in the generation and phenotypic expression of heart failure, and value as specific therapeutic targets remain poorly understood. A growing proportion of heart failure patients, particularly among the elderly, have apparently preserved systolic function, and this is fueling interest for better understanding and treating diastolic abnormalities. Much of the attention in clinical and experimental studies has focused on relaxation and filling abnormalities of the heart, whereas chamber stiffness has been less well studied, particularly in humans. Nonetheless, new insights from basic and clinical research are helping define the regulators of diastolic dysfunction and illuminate novel targets for treatment. This review puts these developments into perspective with the major aim of highlighting current knowledge gaps and controversies. Key Words: myocardium Ⅲ dilated cardiomyopathy Ⅲ heart failure Ⅲ hypertrophy Ⅲ compliance Ⅲ diastole Ⅲ relaxation T he heart spends more than half its time in diastole (relaxing and then filling to prepare for the next ejection). Although abnormalities of diastolic function are well recognized and common to virtually all forms of heart failure, just how they affect basal and reserve function and their relative role in clinical heart failure remain unclear. There are a number of reasons for this. First, diastole assessment ideally requires invasive measurements that are nontrivial to obtain, whereas noninvasive surrogates often reported in clinical studies reflect integrative properties that lack specificity. Second, relatively few animal models recapitulate human diastolic disease, particularly chamber stiffening, which is often normal in murine models despite extensive matrix, myofibrillar, or signaling abnormalities. Third, there are few if any targeted treatments that can specifically test the impact of altering diastolic function on heart failure pathophysiology and outcome. Last, diastolic function has been less amenable to reductionist approaches given the potent roles that chamber geometry, loading (both intrinsic and extrinsic to myocytes), extracellular matrix, and myocardial perfusion all bring to bear.Another problem is that there is no single definition for diastolic dysfunction; many features can be altered, and any one change or their combination is typically called diastolic dysfunction, although the pathophysiology and functional significance varies greatly. Thus, the term is used to describe slowed force (or pressure) decay and cellular relengthening rates, increased (or decreased) early filling rates and deceleration, elevated or steeper diastolic pressure-volume (PV) relations, and filling-rate dependent pressure elevation (viscoelasticity). Clinically, the most common manifestation is an elevated end-diastolic pressure (EDP) and altered filling patterns, but neither of these identifies specific features of diastolic dys...

Abstract-High diastolic stiffness of failing myocardium results from interstitial fibrosis and elevated resting tension (F passive ) of cardiomyocytes. A shift in titin isoform expression from N2BA to N2B isoform, lower overall phosphorylation of titin, and a shift in titin phosphorylation from N2B to N2BA isoform can raise F passive of cardiomyocytes. In left ventricular biopsies of heart failure (HF) patients, aortic stenosis (AS) patients, and controls (CON), we therefore related F passive of isolated cardiomyocytes to expression of titin isoforms and to phosphorylation of titin and titin isoforms. Biopsies were procured by transvascular technique (44 HF, 3 CON), perioperatively (25 AS, 4 CON), or from explanted hearts (4 HF, 8 CON). None had coronary artery disease. Isolated, permeabilized cardiomyocytes were stretched to 2.2-m sarcomere length to measure F passive . Expression and phosphorylation of titin isoforms were analyzed using gel electrophoresis with ProQ Diamond and SYPRO Ruby stains and reported as ratio of titin (N2BA/N2B) or of phosphorylated titin (P-N2BA/P-N2B) isoforms. F passive was higher in HF (6.1Ϯ0.4 kN/m 2 ) than in CON (2.3Ϯ0.3 kN/m 2 ; PϽ0.01) or in AS (2.2Ϯ0.2 kN/m 2 ; PϽ0.001). Titin isoform expression differed between HF (N2BA/N2Bϭ0.73Ϯ0.06) and CON (N2BA/N2Bϭ0.39Ϯ0.05; PϽ0.001) and was comparable in HF and AS (N2BA/N2Bϭ0.59Ϯ0.06). Overall titin phosphorylation was also comparable in HF and AS, but relative phosphorylation of the stiff N2B titin isoform was significantly lower in HF (P-N2BA/P-N2Bϭ0.77Ϯ0.05) than in AS (P-N2BA/P-N2Bϭ0.54Ϯ0.05; PϽ0.01). Relative hypophosphorylation of the stiff N2B titin isoform is a novel mechanism responsible for raised

Background— Excessive diastolic left ventricular stiffness is an important contributor to heart failure in patients with diabetes mellitus. Diabetes is presumed to increase stiffness through myocardial deposition of collagen and advanced glycation end products (AGEs). Cardiomyocyte resting tension also elevates stiffness, especially in heart failure with normal left ventricular ejection fraction (LVEF). The contribution to diastolic stiffness of fibrosis, AGEs, and cardiomyocyte resting tension was assessed in diabetic heart failure patients with normal or reduced LVEF. Methods and Results— Left ventricular endomyocardial biopsy samples were procured in 28 patients with normal LVEF and 36 patients with reduced LVEF, all without coronary artery disease. Sixteen patients with normal LVEF and 10 with reduced LVEF had diabetes mellitus. Biopsy samples were used for quantification of collagen and AGEs and for isolation of cardiomyocytes to measure resting tension. Diabetic heart failure patients had higher diastolic left ventricular stiffness irrespective of LVEF. Diabetes mellitus increased the myocardial collagen volume fraction only in patients with reduced LVEF (from 14.6±1.0% to 22.4±2.2%, P <0.001) and increased cardiomyocyte resting tension only in patients with normal LVEF (from 5.1±0.7 to 8.5±0.9 kN/m 2 , P =0.006). Diabetes increased myocardial AGE deposition in patients with reduced LVEF (from 8.8±2.5 to 24.1±3.8 score/mm 2 ; P =0.005) and less so in patients with normal LVEF (from 8.2±2.5 to 15.7±2.7 score/mm 2 , P =NS). Conclusions— Mechanisms responsible for the increased diastolic stiffness of the diabetic heart differ in heart failure with reduced and normal LVEF: Fibrosis and AGEs are more important when LVEF is reduced, whereas cardiomyocyte resting tension is more important when LVEF is normal.

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