[A quantitative assessment of the impact of diet on the mortality of heart disease in Denmark. Estimation of etiologic fraction]. / En kvantitativ vurdering af kostens betydning for dødeligheden af hjertesygdomme i Danmark. Beregning af aetiologisk fraktion.

INTRODUCTION: The aim of the present study was to quantify the impact of different dietary factors on the mortality from ischaemic heart disease in Denmark. METHODS: Relative risks and knowledge on the distribution of different dietary factors were used to estimate etiological fractions. RESULTS: It is estimated that an intake of fruit and vegetables and saturated fat as recommended would prevent 12 and 22%, respectively, of deaths from ischaemic heart disease in Denmark. An intake of fish among those at high risk for ischaemic heart disease, would lead to a 26% lower mortality, while alcohol intake among abstainers would have no significant quantitative effect. DISCUSSION: These results suggest that changes in dietary habits according to current recommendations would have an impact on public health in Denmark.

Fixed minidose warfarin and aspirin alone and in combination vs adjusted-dose warfarin for stroke prevention in atrial fibrillation: Second Copenhagen Atrial Fibrillation, Aspirin, and Anticoagulation Study.

BACKGROUND: Despite the efficacy of warfarin sodium therapy for stroke prevention in atrial fibrillation, many physicians hesitate to prescribe it to elderly patients because of the risk for bleeding complications and because of inconvenience for the patients. METHODS: The Second Copenhagen Atrial Fibrillation, Aspirin, and Anticoagulation Study was a randomized, controlled trial examining the following therapies: warfarin sodium, 1.25 mg/d; warfarin sodium, 1.25 mg/d, plus aspirin, 300 mg/d; and aspirin, 300 mg/d. These were compared with adjusted-dose warfarin therapy (international normalized ratio of prothrombin time [INR], 2.0-3.0). Stroke or a systemic thromboembolic event was the primary outcome event. Transient ischemic attack, acute myocardial infarction, and death were secondary events. Data were handled as survival data, and risk factors were identified using the Cox proportional hazards model. The trial was scheduled for 6 years from May 1, 1993, but due to scientific evidence of inefficiency of low-intensity warfarin plus aspirin therapy from another study, our trial was prematurely terminated on October 2, 1996. RESULTS: We included 677 patients (median age, 74 years). The cumulative primary event rate after 1 year was 5.8% in patients receiving minidose warfarin; 7.2%, warfarin plus aspirin; 3.6%, aspirin; and 2.8%, adjusted-dose warfarin (P = .67). After 3 years, no difference among the groups was seen. Major bleeding events were rare. CONCLUSIONS: Although the difference was insignificant, adjusted-dose warfarin seemed superior to minidose warfarin and to warfarin plus aspirin after 1 year of treatment. The results do not justify a change in the current recommendation of adjusted-dose warfarin (INR, 2.0-3.0) for stroke prevention in atrial fibrillation.

[Reproducibility of electrocardiographic interpretation in patients with suspected myocardial infarction. A controlled study of the effect of a training trial]. / Reproducerbarheden af bedømmelse af elektrokardiogrammer hos patienter mistaenkt for akut myokardieinfarkt. En kontrolleret undersøgelse af effekten af et undervisiningsforsøg.

We examined the effect of a training programme to reduce interobserver variation in interpretation of electrocardiography in suspected myocardial infarction. Sixteen doctors with 6-24 months of clinical training in internal medicine read serial electrocardiographic recordings in 107 patients and assessed whether signs indicative of acute myocardial infarction were present. There was disagreement in approximately 70% of cases. Eight of the doctors were randomly allocated to attend an eight hour long intensive course on interpretation of electrocardiography in myocardial infarction. The remaining eight participants were allocated to a control group, received no training, and were not told about the subject of the study. All the doctors then reviewed another series of electrocardiographic recordings. No difference was found in the level of agreement within the two groups before and after the training programme, or between the two groups before and after the training. The raters' ability to discriminate between electrocardiograms with a high and low indication of infarction remained unaffected. We conclude that the training programme did not increase agreement regarding the interpretation of electrocardiographic data in suspected myocardial infarction. Our results suggest that the diagnostic approach of physicians is established at a very early stage in their clinical training. The effect of training programmes should be evaluated by the use of randomized clinical studies.

Comparison between reference values for 201thallium uptake and washout from the myocardium after exercise and after dipyridamole.

A slow washout of 201Thallium has a high diagnostic and prognostic value for coronary artery disease. The aim of the present work was to contribute with reference data on 201Tl uptake and washout from the myocardium. With a quantitative method using circumferential profiles and interpolative background subtraction we performed 201Tl myocardial imaging in two groups of subjects with a low probability of coronary artery disease. Washout in per cent is defined as (1-D/I).100, where D is the delayed uptake rate and I the initial uptake rate. In group A (n = 16) myocardial hyperaemia was induced by maximal exercise, in group B (n = 15) by intravenous infusion of dipyridamole. In group A, the mean washout was 52%, and in group B it was 34% (P < 0.001). The delayed uptake rate D was significantly higher after dipyridamole, 58.4 cps, than after exercise, 44.5 cps (P < 0.05). There was no significant differences in I between the two groups. The findings regarding D and I explain that the washout is slower after dipyridamole than after exercise, as the mean D/I ratio was 0.48 in group A and 0.66 in group B (P < 0.001).

Interpretation of the electrocardiogram in suspected myocardial infarction: a randomized controlled study of the effect of a training programme to reduce interobserver variation.

We examined the effect of a training programme to reduce interobserver variation in interpretation of electrocardiography in suspected myocardial infarction. Sixteen doctors with 6-24 months of clinical training in internal medicine read serial electrocardiographic recordings in 107 patients and assessed whether signs indicative of acute myocardial infarction were present. There was disagreement in approximately 70% of cases. Eight of the doctors were randomly allocated to attend an 8-h intensive course on interpretation of electrocardiography in myocardial infarction. The remaining eight participants were allocated to a control group, received no training, and were not told about the subject of the study. All the doctors then reviewed another series of electrocardiographic recordings. No difference was found in the level of agreement within the two groups before and after the training programme, or between the two groups before and after the training. The raters' ability to discriminate between electrocardiograms with a high and low indication of infarction remained unaffected. We conclude that the training programme did not increase agreement regarding the interpretation of electrocardiographic data in suspected myocardial infarction. Our results suggest that the diagnostic approach of physicians is established at a very early stage in their clinical training. The effect of training programmes should be evaluated by the use of randomized clinical studies.

Reliability of first-pass radionuclide determination of cardiac output in the upright position at rest and during exercise.

The reliability of non-invasive determination of cardiac output using first-pass radionuclide cardiography at rest and during exercise in the upright position was evaluated in 20 patients with coronary artery disease. Cardiac output values ranged from 2.97 to 5.99 l/min at rest and from 5.08 to 10.82 l/min during exercise. Cardiac output results obtained by the radionuclide method were compared with those derived from the thermodilution technique performed simultaneously. The mean difference between the two techniques was 0.02 l/min at rest and -0.34 l/min during exercise; the limits of agreement (mean +/- 1.96 SD) were -1.29 to 1.33 l/min and -1.97 to 1.29 l/min, respectively, indicating an acceptable level of agreement. A high reproducibility of the radionuclide technique was found, with a mean difference between determinations by two observers of 0.03 l/min at rest and 0.21 l/min during exercise, the corresponding limits of agreement being -0.75 to 0.81 l/min and -0.79 to 1.21 l/min, respectively. With the aid of a variance component analysis of two determinations by each of four observers, 95% confidence intervals of +/- 10% at rest and +/- 12% during exercise were computed for the radionuclide cardiac output measurements. The observer variation was most pronounced for the part of the cardiac output determination related to measurement of left ventricular equilibrium activity during exercise. First-pass radionuclide cardiography is a reliable method for determination of cardiac output in cardiac patients at rest and during exercise in the upright position.

Magnesium substitution in acute ischaemic heart syndromes.

It has recently been suggested that intravenous infusion of magnesium may reduce mortality and the incidence of serious arrhythmias in patients with ischaemic heart disease and acute myocardial infarction. In the present double-blind, placebo-controlled study, 298 patients with suspected acute myocardial infarction were randomized to receive either intravenous magnesium chloride (80 mmol.24 h-1) or placebo. Infusions were started immediately after admission to the coronary care unit. One hundred and fifty patients received magnesium and 148 the placebo. Ischaemic heart disease was diagnosed in 244 patients. Acute myocardial infarction was observed among 83 patients in the magnesium group and 79 in the placebo group. Both treatment groups were comparable regarding sex, age, clinical status, previous cardiac disease and medication. Serum magnesium was significantly raised during magnesium infusion compared to placebo (P less than 0.01). Fatal events were only observed among patients with myocardial infarction, but neither the in-hospital mortality (magnesium: 12.1%; placebo 10.1%) nor the mortality after a follow-up period of 245 days (median observation time) was affected by magnesium substitution. Magnesium infusion was accompanied by a significantly increased incidence of atrioventricular conduction disturbances. The results suggest that patients suffering from acute ischaemic heart syndromes do not benefit from intravenous magnesium supplementation.