The American journal of cardiology
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Randomized Controlled Trial Comparative Study Clinical Trial
In-laboratory removal of femoral sheath following protamine administration in patients having intracoronary stent implantation.
Two hundred twenty-eight patients with successful coronary stent implantation were randomized either to protamine administration and femoral sheath removal (group I, n = 117) or no heparin neutralization and delayed sheath removal (group II, n = 111). The hospital stay after treatment was shorter in patients receiving protamine; therefore, protamine use for neutralizing circulating heparin may be safely administered immediately after stent implantation.
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Prolonged heart-rate adjusted QT intervals on the electrocardiogram (ECG) are associated with an increased risk for coronary heart disease and sudden death. However, the diagnosis of the prolonged QT interval is hampered by lack of standards. We studied variations in the prevalence of prolonged QT, based on different common definitions, in a large nonhospitalized population, and compared our results with other studies applying the same definitions. ⋯ Comparison with other studies applying the same correction formulas showed large discrepancies in prevalence estimates of prolonged QTc and QTlr, and to a lesser degree of prolonged QTI, possibly due to differences in measurement techniques. Future research is needed to relate QT interval to prognosis, to obtain measurement technique specific reference values of heart-rate adjusted QT measurements, and to obtain age- and sex-specific threshold values for prolonged QT. Such data are needed to use the QT interval with confidence.
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Randomized Controlled Trial Clinical Trial
Rationale, design, and organization of the Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT-HF). The International Steering Committee.
Metoprolol is a cardioselective beta blocker that has been shown to improve left ventricular function and symptoms of congestive heart failure (CHF) and also to decrease the number of hospitalizations due to CHF. However, the effects of metoprolol on mortality in patients with CHF have yet to be determined. Accordingly, the Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT-HF) has been designed to investigate the effect of once-daily dosing of metoprolol succinate controlled release/extended release (CR/XL) when added to standard therapy in patients with CHF. ⋯ The mean follow-up is estimated to be 2.4 years. The study data will be analyzed on an intention-to-treat basis. An Independent Safety Committee will monitor the safety aspects of the trial, and an Independent Endpoint Committee will classify all endpoints.
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About half of all deaths after myocardial infarction (MI) are sudden cardiac deaths. Most of these are thought to be due to ventricular fibrillation (VF). A number of interventions and many different antiarrhythmic agents have been investigated, but so far only beta-blocker therapy has been found to produce significant reductions in the risk of sudden cardiac death after MI. ⋯ Based on observations from animal experiments, it has been proposed that beta blockers with a high degree of lipophilicity penetrate the brain and thereby maintain high vagal tone during stress. A combination of direct anti-ischemic effects due to beta1 blockade and preservation of vagal tone appears to prevent VF in these animal models. Further clinical studies are needed to explore this hypothesis.
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QT interval prolongation and torsades de pointes ventricular tachycardia have been reported after therapeutic doses and overdosage of second generation antihistamines, such terfenadine and astemizol. Diphenhydramine (DPHM), a first generation H1 antagonist, is the most frequently used antihistaminic drug. Despite its widespread use, there are no data about cardiac action and electrocardiographic consequences of DPHM overdose. ⋯ None of the DPHM-overdose patients experienced torsades de pointes. In conclusion, DPHM overdose is associated with a significant increase in heart rate and a significant but moderate QTc prolongation. None of the studied patients, including those who had apparent QTc prolongation, experienced torsades de pointes ventricular tachycardia.