losartan-potassium and Tachycardia--Ventricular

Besides stimulating hematopoiesis, erythropoietin (EPO) protects against experimental ischemic injury in the heart. The present study evaluated the safety and tolerability of EPO treatment in non-anemic patients with acute myocardial infarction (MI).. In this single-center, investigator-initiated, prospective study, patients with a first acute MI were randomized to one bolus of 300 microg darbepoetin alfa or no additional medication before primary coronary intervention. Twenty-two patients (mean age 59 +/- 2 years) were included. In the darbepoetin group, serum EPO-levels increased to 130-270 times that of controls, within the first 24 h. After darbepoetin administration, only small and non-significant changes in hematocrit levels were observed, while endothelial progenitor cells (EPCs, CD34+/CD45-) were increased at 72 h (2.8 vs. 1.0 cells/microl in control group, p < 0.01). No adverse events were recorded during the 30-day follow-up. After 4 months, left ventricular ejection fraction was similar in the two groups (52 +/- 3% in darbepoetin vs. 48 +/- 5% in control group, p = NS).. Intravenous single high-dose darbepoetin alfa in acute MI is both safe and well tolerated. Darbepoetin treatment after MI stimulates EPCs mobilization. The results of this first pilot study support a larger scale clinical trial to establish efficacy of EPO administration in patients after acute MI.

Topics: Angioplasty, Balloon, Coronary; Antigens, CD34; Blood Cell Count; Blood Platelets; Darbepoetin alfa; Electrocardiography; Erythropoietin; Feasibility Studies; Heart Conduction System; Hemoglobins; Humans; Injections, Intravenous; Leukocyte Common Antigens; Male; Mesenchymal Stem Cells; Middle Aged; Myocardial Infarction; Patient Selection; Prospective Studies; Reticulocytes; Tachycardia, Ventricular; Treatment Outcome

Erythropoietin (EPO) is a potent cardioprotective agent in models of myocardial ischemia and reperfusion (I/R). It has been suggested recently that EPO may also reduce ventricular arrhythmia after I/R. The present study investigated the role of neuronal nitric oxide synthase (nNOS) on the antiarrhythmic effects of EPO. EPO treatment increased nNOS expression in isolated neonatal mouse ventricular myocytes. Cotreatment with the phosphatidylinositol 3 (PI3)-kinase inhibitor, LY294002 [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride], or treatment of cardiomyocytes infected with a dominant negative adenovirus targeted to Akt1 (ADV-dnAkt1) blocked the effects of EPO on nNOS expression, suggesting that EPO regulates nNOS expression via PI3-kinase and Akt. To examine the in vivo antiarrhythmic effects of EPO, wild-type (WT) and nNOS(-/-) mice were anesthetized and, after a baseline measurement, subjected to myocardial I/R to provoke ventricular arrhythmias. Pretreatment with EPO 24 h before ischemia increased nNOS expression and significantly reduced the number of premature ventricular contractions (PVCs) and the incidence of ventricular tachycardia (VT) in WT mice. In contrast, treatment with EPO had no effect on PVCs or the incidence of VT in nNOS(-/-) mice. Furthermore, EPO treatment after ischemia significantly reduced the threshold dose of cesium chloride (CsCl) to induce VT. We conclude that EPO via nNOS protects the heart from spontaneous and CsCl-induced ventricular arrhythmia during myocardial I/R.

Topics: Animals; Arrhythmias, Cardiac; Cells, Cultured; Cesium; Chlorides; Electrocardiography; Enzyme Inhibitors; Erythropoietin; Gene Expression; Heart; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Myocytes, Cardiac; Nitric Oxide Synthase Type I; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Tachycardia, Ventricular; Ventricular Premature Complexes