Clinical cardiac electrophysiologic evaluation of the positive inotropic agent, DPI 201-106

DPI 201-106 is a new positive inotropic agent. The cardiac electrophysiology of 16 patients was studied before and during DPI 201-106 administration (loading dose of intravenous DPI 201-106, 1·8 mg kg−1 h−1 administered over 10 min, followed by a maintenance dose of 0·2 mg kg−1 h−1). DPI 201-106 had no effect on the sinus node. The AH interval during fixed-rate atrial pacing became prolonged during DPI 201-106 infusion. There was a significant prolongation of the QT interval [QT (corrected), 417 ± 22 to 502 ± 35 ms, P<0·05; QT (atrial pacing at 600 ms), 374 ±17 to 419 ± 23 ms, P<0·05; QT (ventricular pacing at 600 ms), 409 ± 37 to 449 ± 30 ms, P<0·05]. The ventricular effective refractory period significantly prolonged during DPI 201-106 administration (242 ± 21 to 287 ± 56 ms, P < 0·05), but the supernormal-period duration decreased. The atrial effective refractory period was shortened in four patients and prolonged in one (261 ± 67 to 240 ± 53 ms, NS). The corrected atrial repolarization time (PTac) shortened significantly during DPI 210-106 infusion (479 ± 26 to 445 ± 22 ms at 20 min of the maintenance dose, P<0·05). Atrial fibrillation was initiated in five patients during DPI infusion, but no ventricular arrhythmia was provoked. These findings suggest that DPI 201-106 has novel differential electrophysiological effects on atria and ventricle

The QT interval: a predictor of the plasma and myocardial concentrations of amiodarone.

A study was performed to assess whether plasma and myocardial concentrations of amiodarone correlated with changes on the surface electrocardiogram. Nine patients--seven with angina and two with paroxysmal ventricular tachycardia--were treated with oral amiodarone (200-400 mg daily) for at least nine months before undergoing cardiac surgery. QT intervals were measured from lead II of the surface electrocardiograms recorded before amiodarone treatment and immediately before surgery. Patients with prominent U waves after taking amiodarone were excluded from the study. Plasma and myocardial samples were collected at the beginning of the surgical procedure for estimating plasma and myocardial concentrations using the high performance liquid chromatographic technique. Amiodarone caused a significant lengthening of the QTc interval. There was a good correlation between plasma and myocardial concentrations, and both correlated well with the percentage increase in the QTc interval. Although there was a strong correlation between the dosage given (mg/kg/day) and both plasma and myocardial concentrations, the correlation with the percentage increase in the QTc interval was weaker but still highly significant. Despite previous reports to the contrary, the findings indicate that the plasma concentration of amiodarone does correlate well with the myocardial concentration. The degree of lengthening of the QTc interval may be used clinically to estimate the myocardial concentration of amiodarone

Intracoronary β-radiation to reduce restenosis after balloon angioplasty and stenting. The Beta Radiation In Europe (BRIE) study

Aims The BRIE trial is a registry evaluating the safety and performance of90 Sr delivered locally (Beta-Cath TM system of Novoste) to de-novo and restenotic lesions in patients with up to two discrete lesions in different vessels. Methods and Results In total, 149 patients (175 lesions) were enrolled; 62 treated with balloons and 113 with stents. The restenosis rate, the minimal luminal diameter and the late loss were determined in three regions of interest: (a) in a subsegment of 5mm containing the original minimal luminal diameter pre-intervention termed target segment; (b) the irradiated segment, 28mm in length, and (c) the entire analysed segment, 42mm in length, termed the vessel segment. Binary restenosis was 9·9% for the target segment, 28·9% for the irradiated segment, and 33·6% for the vessel segment. These angiographic results include 5·3% total occlusions. Excluding total occlusions binary restenosis was 4·9%, 25% and 29·9%, respectively. At 1 year the incidence of major adverse cardiac events placed in a hierarchical ranking were: death 2%, myocardial infarction 10·1%, CABG 2%, and target vessel revascularization 20·1%. The event-free survival rate was 65·8%. Non-appropriate coverage of the injured segment by the radioactive source termed geographical miss affected 67·9% of the vessels, and increased edge restenosis significantly (16·3% vs 4·3%, P=0·004). It accounted for 40% of the treatment failures. Conclusion The results of this registry reflect the learning process of the practitioner. The full therapeutic potential of this new technology is reflected by the restenosis rate at the site of the target segment. It can only be unravelled once the incidence of late vessel occlusion and geographical miss has been eliminated by the prolonged use of thienopyridine, the appropriate training of the operator applying this new treatment for restenosis prevention, and the use of longer sources. Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserve