Atrial fibrillation--a review of course and prognosis

Four recent major studies concerning the prognosis in atrial fibrillation (AF) are reviewed. The one-year mortality ranged from 16.0 to 0.2%, highest in elderly, hospitalized patients with chronic AF and lowest in young individuals with paroxysmal AF without other heart disease. The recognized clinical impression that the prognosis in AF is determined by age, type of AF and clinical status is thus confirmed. In three studies, however, the prognosis in lone atrial fibrillation seemed to be poorer than previously thought. The overall rate of thromboembolic complications in AF was about 25% in several studies. The effectiveness of coumarin drugs in the prophylaxis of these complications is not proved, and the time has come to subject them to more careful clinical investigation.

Left ventricular function after myocardial infarction: relation between systolic time intervals and quantitative ischaemic ECG changes

Twentyfour male patients with sustained myocardial infarction (MI) were studied with 12-lead ECG and systolic time intervals (STI) 5 months after the acute episode. From the ECGs were calculated the summed voltages of the R wave (sigma R), the Q wave (sigma Q), and the ST segment deviation (sigma ST). These ischaemic ECG variables were correlated with the STI parameters of left ventricular function: LVETI, PEP and PEP/LVET. Statistically significant regression equations relating the ECG changes to the STI variables were found in anterior MI, for sigma ST in the entire series, but not in inferior MI. Thus a simple and rapid inspection of the resting 12-lead ECG gives an indirect but reliable quantitative estimate of left ventricular function in patients with a sustained myocardial infarction.

Cardiac disease in patients with reversible cerebral ischemic events

The establishment of a possible association between ischemic cerebral attacks and prolapsing mitral valve has been studied in 45 consecutive patients aged 60 years or less with transient cerebral ischemic attacks and reversible ischemic neurological deficits. The study comprised cardiac history, auscultation, electrocardiography and echocardiography. We found only one patient (2%) with mitral valve prolapse but 19 patients (42%) with cardiac abnormalities. Two of the patients with cardiac abnormalities had a flail posterior mitral leaflet, one had ventricular septal defect and one had sclerotic aortic valves. We conclude that all patients with transient cerebral ischemic attacks should be subjected to heart examination, if possible including echocardiography.

Echocardiography in lone atrial fibrillation

Twenty-seven consecutive patients with suspected lone atrial fibrillation were studied by M-mode echocardiography. Echocardiography disclosed structural or functional cardiac abnormalities in only two (12%) of 17 patients without any sign of underlying heart disease by history or physical examination, whereas an accompanying or underlying cardiac disorder was found in 6 (60%) of 10 patients with ambiguous clinical findings. It is concluded that echocardiography is of minor value in patients with lone atrial fibrillation if symptoms and signs of other cardiac disorders are totally absent, but the presence of even minor or ambiguous clinical abnormalities seems to be a clear indication for echocardiography in these patients. It is, however, emphasized that echocardiography appears to guide the clinical management in less than 20% of patients with clinically suspected lone atrial fibrillation.

Pericardiocentesis in patients with and without incipient cardiac tamponade due to pericardial effusion. An easy and safe bedside approach

Fourteen patients with pericardial effusion of various origins underwent pericardiocentesis on 16 occasions. Incipient cardiac tamponade was present on 19 occasions in 12 patients. Pericardiocentesis was carried out bedside under sterile conditions by a trained cardiologist. In case of impaired central circulation, drainage was sufficient to stabilize the clinical condition haemodynamically, and no adverse events occurred during pericardiocentesis. Fenestration of the parietal pericardium was necessary in 5 patients because of rapid regeneration of the fluid and in one patient due to pyopericardium with cardiac constriction. Pericardiocentesis is recommended in incipient cardiac tamponade. In the hands of experienced cardiologists the drainage procedure can be carried out safely without sophisticated equipment.

[A quantitative assessment of the impact of diet on the mortality of heart disease in Denmark. Estimation of etiologic fraction]

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.

Olive oil and the Mediterranean diet: implications for health in Europe

At a meeting convened by the European Commission at the Italian National Research Council in Rome, 11 April 1997, European nutrition, cardiology, lipidology and public health specialists gathered to reach a health consensus on olive oil and the Mediterranean diet.

[Reproducibility of electrocardiographic interpretation in patients with suspected myocardial infarction. A controlled study of the effect of a training trial]

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).

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.

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.

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.

[Atrial fibrillation--thromboembolism and prevention]

Chronic non-rheumatic atrial fibrillation is associated with a risk of thromboembolic complications of about 5% per year. Previous myocardial infarction seems to be a significant risk factor for development of thromboembolic complications in chronic atrial fibrillation, whereas paroxysmal atrial fibrillation and isolated atrial fibrillation in younger patients may be associated with a lower risk of emboli. Silent cerebral infarction occurs more often in chronic atrial fibrillation than among controls in sinus rhythm. Three prospective trials of patients with atrial fibrillation found effect of warfarin on the occurrence of thromboembolic complications. In one study aspirin 325 mg daily was effective in patients below 75 years of age, but not in patients above this age. The other trials revealed no effect of aspirin.

Atrial fibrillation and left atrial enlargement: cause or effect?

In a blinded controlled study, 58 consecutive patients with definite left atrial enlargement (M-mode dimension of at least 45 mm) were followed up after 1-2 years. The aim of the study was to examine the following: (a) the prospective risk of developing atrial fibrillation (AF); and (b) the effect of the heart rhythm on the left atrial size. Of 36 patients in sinus rhythm, one developed paroxysmal AF and one developed persistent AF during a median follow-up period of 20 months. Thus the incidence of new AF was 5% per year. Eighteen patients died before scheduled echocardiographic follow-up, but in the remaining subjects the left atrial dimension did not change significantly: the median increment was 1 mm in 20 patients who sustained sinus rhythm vs 2 mm in 16 patients with chronic AF (P greater than 0.05). Although left atrial dilatation may cause AF and vice versa, this study demonstrated that the incidence of new AF is low, despite the fact that the left atrial dimension is substantially increased. Similarly, AF per se does not appear to have any major impact on the left atrial dimension.

The value of the left ventricular ejection fraction in the treatment of angina pectoris following acute myocardial infarction: a randomized double blind study

Radionuclide determination of left ventricular ejection fraction was performed at hospital discharge and one month later in 60 patients who had suffered acute myocardial infarction. At the first determination, the patients were randomized into two groups. In the first group, the cardiologist who cared for the patients was provided with the result of the determination of the ejection fraction whereas, in the second group, the result was withheld. At a 'blinded' evaluation two months after hospital discharge, 7 of those patients (24%) from the group where the cardiologist knew the ejection fraction and 11 of the patients (38%) in whom this result was withheld complained of angina pectoris on exertion (ns). The medication of the patients did not differ in the two groups. No significant difference was found in the values of the ejection fraction in patients with and without angina pectoris. In this controlled study, we were not able to document a clinical effect by routinely determinating left ventricular ejection fraction in patients with acute myocardial infarction in the treatment of angina pectoris.

[Treatment of acute myocardial infarction--an elucidative report]

The present-day optimal treatment of patients with acute myocardial infarction (AMI) is reviewed. The prehospital phase should be as brief as possible. Emergency observation and treatment in hospital should be initiated without delay. Schematic stages for mobilization have been discarded and free mobilization is recommended. Routine acute intervention with thrombolysis is recommended for patients in whom symptoms have been present for 6-12 hours and treatment with Aspirin is recommended. Beta-blocking agents are recommended for patients with increased risk after discharge. Treatment of ventricular and supraventricular arrhythmias, block and cardiac failure are reviewed in detail. Patients without complications should be monitored for three to five days and may be discharged after seven to ten days. Exercise ECG should be carried out at discharge to assess the working capacity, ischaemia and subjective reaction. The importance of good patient information is emphasized. Cessation of smoking, control of lipids and blood pressure are important as secondary interventions. As far as possible, outpatient control should be offered after discharge. The criteria for referral to specialized cardiological departments are established both for emergency and elective referral. Patients under the age of 70 years with high risk for repeated AMI or death after discharge (with residual ischaemia) should possibly be referred for coronary arteriography.

Cerebral computed tomography in paroxysmal atrial fibrillation

Atrial fibrillation (AF) is associated with an increased risk of stroke. In patients with chronic AF, without clinically known cerebrovascular disease, computed tomography (CT) has revealed a high frequency of abnormal low-density areas suggesting old asymptomatic infarcts. To investigate the frequency of such lesions in paroxysmal AF, 30 patients with paroxysmal AF and 30 controls matched in sinus rhythm, without history of cerebrovascular disease, were CT scanned. Four patients with paroxysmal AF (13%) and 3 controls (10%) had abnormal CT scans with areas of low density with sharp demarcation from surrounding tissue. The abnormal areas probably reflected small, clinically silent infarcts. There were no differences between paroxysmal AF and controls in number and size of abnormal areas with apparent tissue loss. In contrast to chronic AF, the risk of such lesions in paroxysmal AF does not seem to be increased compared with matched sinus rhythm controls. This is in agreement with the clinical experience of a low risk of stroke in paroxysmal AF.

Central haemodynamic changes after a meal

Eight healthy people (seven men and one woman, aged 19 to 31 years) were studied by radionuclide cardiography when supine before and 30 minutes after a standard meal (6300 kJ). Control investigations were performed on a different day within a week of the standard meal. There was a median increase in cardiac output of 62% that was attributable to a 17% increase in heart rate and a 41% increase in stroke volume. Blood pressure and concentrations of plasma catecholamines did not change. The median end diastolic and end systolic volumes of the left ventricle increased by 41% so that the left ventricular ejection fraction was unchanged. There were no significant changes during the control experiments. In healthy people a meal caused an appreciable increase in stroke volume and dilatation of the left ventricle. The activity of the sympathetic nervous system, as measured by plasma catecholamines, did not change much, and changes in blood volume alone did not seem to explain the haemodynamic response to the meal.

First passage radionuclide cardiography for determination of cardiac output: evaluation of an improved method

A noninvasive method for determination of cardiac output by aid of first passage radionuclide cardiography is presented. As opposed to most other scintigraphic methods, a forward blood flow is measured, even in patients with valvar incompetence. In addition, the technique allows measurement of cardiac output in the presence of cardiac arrhythmias. No geometrical assumptions, corrections for radiation attenuation, loss of tracer, or empirical correction factors due to extracardiac radioactivity are required. We have evaluated the method in 19 patients with various heart diseases by comparison of the radionuclide cardiac outputs with those derived from the thermodilution technique performed simultaneously. Eight patients had valvar incompetence and 2 had cardiac arrhythmias. The mean radionuclide and thermodilution cardiac output values were 5.03 l/min (SD 1.21) and 5.18 l/min (SD 1.09), respectively. The 95% confidence interval for the bias was -0.40 to 0.10 l/min, and correlation analysis demonstrated an excellent correlation between results obtained with the two methods, r = 0.91 (P less than 0.001). This study shows that the improved gamma camera method represents a valid noninvasive technique for determination of cardiac output.

The veteran athlete: an echocardiographic comparison of veteran cyclists, former cyclists and non-athletic subjects

To determine the effects of prolonged endurance training on the heart, a comparison was made of veteran cyclists aged 41-51 years, former cyclists, and non-athletic subjects, including echocardiography, ECG, systolic and diastolic time intervals, and maximal oxygen uptake. The veterans had significantly larger diastolic diameter, systolic diameter, thickness of septum, posterior wall, and left ventricular mass. The enlargement of the left ventricle was found to be proportionate, as the ratio of diastolic diameter to wall thickness showed no change. In contrast to earlier reports, no indication of reduced cardiac function was found in the veterans, as echocardiographically measured function parameters, systolic, and diastolic time intervals were similar in the three groups. In the former athletes, whose previous training experience was similar to that of the veterans, no significant variation in cardiac structure and function was found in relation to the control group. This indicates that the physiological hypertrophy caused by physical training can be reversible.

Central hemodynamic changes after ingestion of a meal in patients with coronary artery disease

Thirty-six patients with coronary artery disease participated in a controlled trial of the influence of food intake on central hemodynamic parameters determined noninvasively by radionuclide cardiography. Stroke volume increased considerably (23%) and heart rate was slightly higher (8%) half an hour after the meal, whereas the elevated cardiac output two hours postprandially could be ascribed entirely to relative tachycardia. No significant hemodynamic changes occurred in the patients who fasted. That the left ventricular ejection fraction was increased postprandially (3% to 4%) indicated that food intake had positive inotropic as well as chronotropic effects on the ischemic heart, even in heart failure. Afterload reduction and increased sympathetic nervous activity contribute to the changes, but the primary mechanism may be a change in resistance and blood flow in the intestinal vascular bed involved in digestion.

Prospective evaluation of chronic cardiotoxicity due to high-dose epirubicin or combination chemotherapy with cyclophosphamide, methotrexate, and 5-fluorouracil

In a prospective study the left ventricular ejection fraction (LVEF), right ventricular ejection fraction (RVEF), systolic blood pressure, ECG, and heart rate were recorded at rest and during submaximal work to compare the cardiotoxic effect of epirubicin with a combination chemotherapy without known cardiotoxicity. A total of 14 females with advanced breast cancer were treated with epirubicin at a median cumulative dose of 827 mg/m2 (range, 550-1244). These patients had previously received cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) or cyclophosphamide alone as adjuvant treatment, or CMF for advanced disease. The control group consisted of 11 females with advanced breast cancer given CMF only. The systolic blood pressure at rest as well as during submaximal work was significantly lower (P less than 0.05) after treatment in the epirubicin group than in the CMF controls. With regard to LVEF, the median value of 54% at rest was significantly lower after treatment in the epirubicin group than in the controls (59%). There was a significant fall in LVEF at rest and during exercise in the epirubicin group, whereas no such changes were found in the CMF controls after treatment. The RVEF was unaffected. In the epirubicin-treated group one patient developed fatal congestive heart failure, and in the remaining 13 patients treatment was discontinued due to progression of the cancer and not to cardiotoxicity. Thus, the cardiotoxicity of epirubicin changed the clinical outcome in only 1 of 14 patients with advanced breast cancer.

Placebo-controlled, randomised trial of warfarin and aspirin for prevention of thromboembolic complications in chronic atrial fibrillation. The Copenhagen AFASAK study

From November, 1985, to June, 1988, 1007 outpatients with chronic non-rheumatic atrial fibrillation (AF) entered a randomised trial; 335 received anticoagulation with warfarin openly, and in a double-blind study 336 received aspirin 75 mg once daily and 336 placebo. Each patient was followed up for 2 years or until termination of the trial. The primary endpoint was a thromboembolic complication (stroke, transient cerebral ischaemic attack, or embolic complications to the viscera and extremities). The secondary endpoint was death. The incidence of thromboembolic complications and vascular mortality were significantly lower in the warfarin group than in the aspirin and placebo groups, which did not differ significantly. 5 patients on warfarin had thromboembolic complications compared with 20 patients on aspirin and 21 on placebo. 21 patients on warfarin were withdrawn because of non-fatal bleeding complications compared with 2 on aspirin and none on placebo. Thus, anticoagulation therapy with warfarin can be recommended to prevent thromboembolic complications in patients with chronic non-rheumatic AF.

The reliability of measuring left ventricular ejection fraction by radionuclide cardiography: evaluation by the method of variance components

A statistical model based on the method of variance components was applied to obtain confidence statements for single and repeat determinations of left ventricular ejection fraction by radionuclide techniques. With this approach variance caused by individual factors in the measurement procedure is estimated to allow calculation of confidence intervals based on single measurements and the detection limits for changes. Six study groups made up of a total of 143 subjects were examined by both multigated equilibrium and first pass imaging. Under favourable conditions (with an updated gamma camera and experienced observer) the 95% confidence interval with a single measurement of left ventricular ejection fraction by equilibrium imaging was +/- 3 ejection fraction units, compared with +/- 6 units with the first pass technique (one ejection fraction unit = 1/100 of the possible values from 0.00 to 1.00). The minimal significant changes (at the 5% level) in measured equilibrium left ventricular ejection fraction at intervals of 15 min, 3 days, 1, 3, and 4 weeks were +/- 4, +/- 4, +/- 5, +/- 5, and +/- 6 units, respectively. The corresponding minimal detectable changes in a subject's "true" left ventricular ejection fraction for the same intervals were +/- 7, +/- 7, +/- 10, +/- 10, and +/- 12 units respectively. With first pass imaging, only average values for the variation at repeat determination could be calculated. The minimal significant change in measured first pass left ventricular ejection fraction was +/- 7 units, and the minimal detectable change in "true" left ventricular ejection fraction was +/- 14 units. Measurements of left ventricular ejection fraction by equilibrium technique were generally more reproducible than first pass determinations because the variability caused by study acquisition, observer analysis, and residual errors was smaller. The method of variance components appears to be well suited to the evaluation of quantitative biological measurements in clinical use. The popularity of established procedures may obscure the lack of basic information about method evaluation.

Risk factors for stroke in chronic atrial fibrillation

Atrial fibrillation is associated with an increased risk of stroke. Different risk factors may be of importance regarding stroke incidence and mortality in atrial fibrillation. Retrospectively, we studied 786 patients with chronic atrial fibrillation, 229 with rheumatic heart disease and 557 without. In all, 127 patients had stroke (16%). Using Cox's proportional hazard model for failure-time data with age, gender, etiology, degree of heart failure and cardiac enlargement as explanatory (independent) variables, only etiology (rheumatic heart disease) was a significant risk factor for stroke (P less than 0.006). Significant risk factors for death in 653 patients without stroke were age (P = 0.000) and congestive heart failure at the onset of atrial fibrillation (P = 0.000). The need to identify other risk factors for stroke in patients with atrial fibrillation is emphasized, for selecting patients at high risk for prophylactic treatment with anticoagulants or aspirin.

Cardiac function at rest and during exercise in early and late alcohol intoxication

Seven healthy men, aged 21 to 30 years, were investigated by radionuclide cardiography at rest and during submaximal exercise at heavy (early) and during declining (late) alcohol intoxication. Control studies, in which alcohol was substituted by an isocaloric, isovolumic drink, were performed on a different day. The left ventricular ejection fraction at rest decreased from 59 to 56% during early intoxication (serum ethanol 35 +/- 6 mmol/l), whereas no change was observed in the ejection fraction during exercise. No significant change was recorded in stroke volume after alcohol consumption as opposed to a small increase after ingestion of the caloric drink. Plasma noradrenaline concentrations were elevated during exercise and early intoxication. During late intoxication (serum ethanol 21 +/- 5 mmol/l) the left ventricular ejection fraction at rest was increased by 7% compared with the baseline value. At rest the heart rate was increased from 68 +/- 7 to 84 +/- 15 beats/min, whereas cardiac output had reverted to the baseline value. Plasma noradrenaline at late intoxication was increased both at rest and during exercise compared with the baseline values. Apart from tachycardia and a reduction in left ventricular volumes during late intoxication no alcohol induced hemodynamic changes occurred during exercise.

Left ventricular volumes during graded upright exercise in healthy untrained subjects

Left ventricular (LV) volume changes were studied by radionuclide cardiography at rest and during graded upright bicycle exercise in seven healthy untrained men aged 21-30 years. The exercise-induced changes in LV volumes were most pronounced during mild exercise: from rest to 25% submaximal exercise stroke volume increased by 26% and LV ejection fraction from 0.60 to 0.69 (both P less than 0.01), whereas further increments of the work load resulted in only small changes of these variables. LV end-diastolic volume increased initially by 10% (P less than 0.05) but returned to baseline values at higher work loads, whilst a rather constant decrease was recorded in LV end-systolic volume during increasing exercise loads. Changes in plasma catecholamine levels were most pronounced at the high work loads, indicating that these hormones are not directly contributing to the LV volume changes.

Atrial fibrillation: natural history, complications, and management

Atrial fibrillation is a clinically important arrhythmia that carries important prognostic and therapeutic implications. Hypertension, ischemic heart disease, and rheumatic valvular disease are the commonest causes of atrial fibrillation. The presence of chronic or paroxysmal atrial fibrillation places the patient at increased risk for embolic stroke and/or death. When atrial fibrillation develops, there is loss of the atrial transport factor ("atrial kick"), with consequent decrease of cardiac output. Stroke output declines by 20-30% in normal individuals with loss of atrial kick; the decline in stroke output is considerably larger in patients with heart disease. Atrial fibrillation can be electrically or pharmacologically reverted to sinus rhythm. Even patients with refractory atrial fibrillation can be reverted to sinus rhythm with amiodarone.

Hemodynamic effects of alcohol at rest and during upright exercise in coronary artery disease

The hemodynamic effects of acute alcohol intoxication were studied at rest and during upright exercise in 28 patients with coronary artery disease by right-sided heart catheterization and radionuclide cardiography. The mean arterial blood pressure at rest was reduced by 5% and the left ventricular ejection fraction at rest decreased 2% because of end-systolic dilation during intoxication (serum ethanol 21 mmol/liter). No changes were observed in heart rate, stroke volume, pulmonary artery pressure, pulmonary artery wedge pressure or total peripheral resistance. No significant changes occurred in plasma catecholamines, and no changes occurred in any variable during mild exercise corresponding to a 30 to 40% heart rate increase. Thus, alcohol ingested in moderate doses causes slight impairment of left ventricular emptying and a reduction in the arterial blood pressure at rest in patients with coronary artery disease. A mild exercise load can be tolerated during alcohol intoxication without hemodynamic changes.

Autonomic nervous control of postprandial hemodynamic changes at rest and upright exercise

Postprandial hemodynamic changes were studied in healthy subjects at rest and during exercise in the upright position with and without autonomic blockade of the heart. At rest cardiac output increased 61% mostly because of a stroke volume increase accomplished by left ventricular end-diastolic dilation. These changes seemed to be dependent on the autonomic nervous system, whereas the postprandial heart rate increase did not. During exercise cardiac output was 23% higher after food intake due to a rise in both stroke volume and heart rate. These changes were apparently under influence of the autonomic nervous system, whereas left ventricular dilation was not. The present findings indicate that most of the postprandial changes in the central circulation are under control of the autonomic nervous system.

Left ventricular performance in alcoholic patients without chronic liver disease

Left ventricular performance was studied non-invasively in 24 chronic alcoholics without liver disease. Twelve patients who had abstained from drinking for at least one month (group A) and 12 sex and age matched patients who had ceased drinking during the preceding 24 hours (group B) were studied at rest and during 50% submaximal exercise. Cardiac output and stroke volume were measured by first passage and left ventricular ejection fraction by multigated radionuclide cardiography. Twelve healthy sex and age matched controls were also studied. Haemodynamic variables were similar in group A and the controls, except that in group A left ventricular end systolic volume index did not decrease during exercise. In group B the heart rate was increased both at rest and during exercise and plasma noradrenaline concentrations were increased. The stroke volume index did not increase significantly during exercise in group B. In addition, the increase in left ventricular ejection fraction was smaller in group B than in controls. End systolic contraction was reduced in group B patients and diastolic blood pressure was increased. These results suggest that cardiac abnormalities in chronic alcoholics may be reversed after cessation of drinking if no chronic liver disease is present. Recent alcohol consumption increases sympathetic nervous activity, impairs cardiac contractility, and increases afterload during physical stress.