European heart journal
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European heart journal · Dec 1995
Randomized Controlled Trial Comparative Study Clinical TrialEffect of metoprolol on death and cardiac events during a 2-year period after coronary artery bypass grafting. The MACB Study Group.
To evaluate the effect of long-term treatment with metoprolol after coronary bypass grafting on death and cardiac events. ⋯ Prophylactic treatment with metoprolol over a 2-year period after coronary artery bypass grafting did not reduce death or the development of cardiac events. However, the 95% confidence limits ranged from the possibility of a 30% reduction in events to a 68% increase in events if patients were treated with metoprolol as compared with placebo.
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European heart journal · Dec 1995
Inferior ST segment depression as a useful marker for identifying proximal left anterior descending artery occlusion during acute anterior myocardial infarction.
To determine whether or not ST segment deviation on admission electrocardiograms can identify patients with anterior acute myocardial infarction due to proximal left anterior descending artery occlusion, the magnitude and location of ST segment elevation or depression were compared between patients with proximal left anterior descending artery occlusion (group A, n = 47) and those with distal left anterior descending artery occlusion (group B, n = 59). ST segment depression in each of the inferior leads was significantly greater in group A than in group B. The incidence of ST segment depression > or = 1 mm in each of the inferior leads (II; 81% vs 27%, III; 85% vs 54%, aVF; 87% vs 47%, P < 0.01) was significantly higher in group A than in group B. ⋯ ST segment depression > or = 1 mm in all of the inferior leads was most valuable for identifying group A patients (77% sensitivity and 78% specificity). In contrast, the maximal ST segment elevation in lead V2 alone or ST segment elevation > or = 1 mm in lead aVL had a low diagnostic value (43% sensitivity and 86% specificity, 66% sensitivity and 53% specificity, respectively). In conclusion, this study indicates that analysis of ST segment deviation in the inferior leads is useful for identifying patients with acute anterior myocardial infarction due to proximal left anterior descending occlusion.
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European heart journal · Dec 1995
Time domain analysis of the signal averaged electrocardiogram in patients with a conduction defect or a bundle branch block.
Doubts have been expressed about the clinical usefulness of time domain analysis of the signal averaged electrocardiogram in patients with prolonged QRS complex duration. We studied 147 patients using a signal averaged ECG (40-250 Hz) whose QRS complex was longer than 100 ms. A baseline electrophysiology study was also performed in 128 of these patients. ⋯ The same criteria applied to patients with a major conduction defect were sensitive (sensitivity: 87%) but non-specific (specificity: 50%). However, by using modified late potential criteria, such as the presence of two of any of the following three signal averaged parameters: filtered QRS duration > or = 145 ms, low amplitude signal duration > or = 50 ms, root mean square of the last 40 ms of the filtered QRS complex < or = 17.5 microV, we derived a non-optimal but still acceptable combination of sensitivity (68%) and specificity (73%). We conclude that traditional late potential criteria can be applied in patients with a minor conduction defect, but modification of these criteria is necessary to derive useful clinical information for risk stratification of patients with a QRS complex duration > or = 120 ms.
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European heart journal · Nov 1995
Comparative StudyA comparison of non-invasive continuous finger blood pressure measurement (Finapres) with intra-arterial pressure during prolonged head-up tilt.
Simultaneous intra-radial and non-invasive (Finapres, Ohmeda) blood pressures were compared during prolonged head-up tilt, in eight patients (mean age 49 years) with malignant vasovagal syncope. Twelve tilts were performed, of which eight resulted in vasovagal syncope. The mean bias (difference between Finapres and intra-arterial pressures) for systolic pressure was +0.7 mmHg (standard deviation 11.3 mmHg) and for diastolic pressure was +5.4 mmHg (standard deviation 7 mmHg). ⋯ In all but one tilt highly significant positive increases in both systolic (median 7.1 mmHg) and diastolic bias (median 8.1 mmHg) occurred on tilt with respect to resting pre-tilt levels. Independent of the absolute level of agreement, the non-invasive measurements followed changes in intra-arterial pressure closely, with 89% of beat-to-beat changes in systolic pressure, and 95% of beat-to-beat changes in diastolic pressure followed to within +/- 2 mmHg. This study suggests that the Finapres is well suited for use during diagnostic tilt testing, demonstrating an acceptable within-tilt precision and closely following pressure changes during vasovagal syncope.
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European heart journal · Nov 1995
Utilization of oxygen by the contractile apparatus is disturbed during reperfusion of post-ischaemic myocardium.
Post-ischaemic ventricular function remains depressed (= myocardial stunning) despite nearly normal coronary blood flow during reperfusion. In order to illuminate the causes of this phenomenon, we studied the relationship between ventricular function and myocardial oxygen consumption (MVO2tot) in experiments on 15 isolated rabbit hearts perfused with erythrocyte suspension (hct = 30%). Left ventricular systolic function was assessed by measuring aortic flow (ml.min-1), peak systolic pressure (LVPmax), dP/dtmax, and early relaxation in terms of dP/dtmin during control and 30 min after the onset of reperfusion, following 20 min global no-flow ischaemia. The pressure-volume area was calculated as a measure of total mechanical energy. The external mechanical efficiency (Eext) was assessed from stroke work and MVO2tot. Both contractile efficiency (Econ = inverse slope of the MVO2-PVA relationship) and MVO2 of the unloaded contracting heart (MVO2unl = basal MVO2 + MVO2 for excitation-contraction coupling) were calculated using pressure-volume area and MVO2tot. ⋯ Ventricular function after brief episodes of ischaemia is decreased whereas MVO2tot is maintained, i.e. external efficiency is decreased. MVO2 for the unloaded contraction remained unchanged, indicating that MVO2 for excitation-contraction coupling is inappropriately high for the depressed contractile state. The decreased contractile efficiency indicates further that O2 utilization of the contractile apparatus is disturbed during reperfusion.