Afterload-induced left ventricular diastolic dysfunction during myocardial ischaemia and reperfusion.

NEW FINDINGS: What is the central question of this study? While the load dependence of the diastolic function is established for the normal heart, little is known about the response of the acutely ischaemic and reperfused myocardium to alterations in afterload. What is the main finding and its importance? Using a model that simulates the clinical scenario of acute ischaemia-reperfusion, we show that increased afterload aggravates diastolic dysfunction during both acute ischaemia and reperfusion. In addition, increased afterload induces diastolic dyssynchrony, which might be the underlying mechanism of the diastolic dysfunction of the ischaemic myocardium. These findings provide us with new information regarding how better to manage patients who undergo revascularization therapy after acute myocardial infarction. The effects of changes in left ventricular (LV) afterload on diastolic function of acutely ischaemic and reperfused myocardium have not been studied in depth. We examined the following factors: (i) the consequences of increasing the LV afterload on LV diastolic function during acute ischaemia and reperfusion; (ii) whether the myocardial response to afterload elevation is stable throughout a 2 h reperfusion period; and (iii) the role of LV wall synchrony in the development of afterload-induced diastolic dysfunction. We instrumented 12 anaesthetized, open-chest pigs with Millar pressure catheters and piezoelectric crystals before ligating mid-left anterior descending coronary artery for 1 h, followed by reperfusion for 2 h. Six of the animals survived throughout the 2 h of reperfusion, and their data were used for comparisons across the different experimental phases. Left ventricular afterload was increased by inflating an intra-aortic balloon. Data were recorded at baseline, after 20 min of coronary occlusion and at 30 and 90 min of myocardial reperfusion. The increased afterload for 2 min lengthened the isovolumic relaxation during ischaemia and during early and late reperfusion but had no significant effect on isovolumic relaxation before coronary artery occlusion. Increasing the afterload aggravated LV diastolic dyssynchrony during coronary artery occlusion, but not during reperfusion. The afterload-induced prolongation of isovolumic relaxation was positively correlated with afterload-induced diastolic dyssynchrony. These observations indicate that, during myocardial ischaemia and throughout reperfusion, LV diastolic function is afterload dependent. Afterload-induced diastolic dyssynchrony might be an underlying mechanism of diastolic dysfunction during acute ischaemia.

Intracoronary Administration of Allogeneic Cardiosphere-Derived Cells Immediately Prior to Reperfusion in Pigs With Acute Myocardial Infarction Reduces Infarct Size and Attenuates Adverse Cardiac Remodeling.

BACKGROUND: Allogeneic cardiosphere-derived cells (CDCs) exert cardioprotective effects when administered intracoronarily after reperfusion in animal models of acute myocardial infarction (AMI). The "no-reflow" phenomenon develops rapidly post-reperfusion and may undermine the efficacy of cell therapy, due to poor cell delivery in areas of microvascular obstruction (MVO). We hypothesized that CDC-induced cardioprotection would be enhanced by cell administration prior to reperfusion, when microvasculature is still relatively intact, to facilitate widespread cell delivery within the ischemic area. METHODS AND RESULTS: We studied 81 farm pigs; 55 completed the specified protocols. A dose-optimization study in infarcted pigs demonstrated that the doses of 5 million and 10 million CDCs are the maximum safe doses that can be administered intracoronarily at 5 minutes prior to and at 5 minutes post-reperfusion, respectively, without aggravating MVO. Quantification of acute cell retention by polymerase chain reaction demonstrated that cell delivery prior to reperfusion resulted in higher cardiac cell retention compared to delivery post-reperfusion. We then performed a randomized, placebo-controlled study to assess the long-term efficacy of intracoronary infusion of 5 million allogeneic CDCs, delivered at 5 minutes prior to reperfusion, in a porcine model of AMI. The CDC therapy resulted in decreased scar size, improved regional systolic function, and attenuation of adverse cardiac remodeling (manifested as preserved global systolic function, preserved end-systolic volume, and decreased interstitial fibrosis) compared to placebo at 30 days post-MI. CONCLUSIONS: Dose-optimized intracoronary infusion of allogeneic CDCs prior to reperfusion in a porcine model of AMI is feasible, safe and confers long-term benefits.

Red blood cell distribution width is a significant prognostic marker in advanced heart failure, independent of hemoglobin levels.

INTRODUCTION: Advanced heart failure (HF) is associated with increased morbidity and mortality; traditionally used prognostic factors often fail to predict the outcome. Increased red blood cell distribution width (RDW) has recently been recognized as an important unfavorable prognostic factor in HF, independent of anemia; however, the role of RDW in patients with advanced HF has not yet been investigated. METHODS: Eighty consecutive patients with stage D heart failure, recently hospitalized for HF decompensation, were enrolled. A Cox proportional-hazard model was used to determine whether RDW was independently associated with outcome. RESULTS: At study entry, ejection fraction (EF), pulmonary capillary wedge pressure (PCWP), hemoglobin (Hb) and RDW were 25 ± 8.6%, 27.5 ± 8 mmHg, 12.5 ± 1.9 mg/dL and 18 ± 3.5% (normal <14.5%) respectively. At 6 months, 44 patients (55%) had died. In this patient population, EF (p=0.45), PCWP (p=0.106), age (p=0.54), albumin (0.678), iron (p=0.37), creatinine (p=0.432), iron deficiency defined by bone marrow aspiration (p=0.37), bilirubin (p=0.422), peak VO2 (p=0.057) and Hb (p=0.95) were not significant predictors of a worse outcome. However, RDW was a significant marker for adverse prognosis (p=0.007, HR: 1.14, CI: 1.04-1.24) and retained its prognostic significance even when corrected for Hb values (HR: 1.15, CI: 1.05-1.27, p=0.003). CONCLUSIONS: RDW is a significant prognostic factor for an adverse outcome in patients with advanced stage heart failure who have experienced recent decompensation, independent of the presence of anemia or malnutrition, and is superior to more traditionally used indices. RDW may be associated with severe disease by reflecting subtle metabolic and proinflammatory abnormalities in HF.