Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) therapy has been shown to improve survival in patients with various heart conditions who are at high risk for ventricular arrhythmias. Whether benefit occurs in patients early after myocardial infarction is unknown. METHODS: We conducted the Defibrillator in Acute Myocardial Infarction Trial, a randomized, open-label comparison of ICD therapy (in 332 patients) and no ICD therapy (in 342 patients) 6 to 40 days after a myocardial infarction. We enrolled patients who had reduced left ventricular function (left ventricular ejection fraction, 0.35 or less) and impaired cardiac autonomic function (manifested as depressed heart-rate variability or an elevated average 24-hour heart rate on Holter monitoring). The primary outcome was mortality from any cause. Death from arrhythmia was a predefined secondary outcome. RESULTS: During a mean (+/-SD) follow-up period of 30+/-13 months, there was no difference in overall mortality between the two treatment groups: of the 120 patients who died, 62 were in the ICD group and 58 in the control group (hazard ratio for death in the ICD group, 1.08; 95 percent confidence interval, 0.76 to 1.55; P=0.66). There were 12 deaths due to arrhythmia in the ICD group, as compared with 29 in the control group (hazard ratio in the ICD group, 0.42; 95 percent confidence interval, 0.22 to 0.83; P=0.009). In contrast, there were 50 deaths from nonarrhythmic causes in the ICD group and 29 in the control group (hazard ratio in the ICD group, 1.75; 95 percent confidence interval, 1.11 to 2.76; P=0.02). CONCLUSIONS: Prophylactic ICD therapy does not reduce overall mortality in high-risk patients who have recently had a myocardial infarction. Although ICD therapy was associated with a reduction in the rate of death due to arrhythmia, that was offset by an increase in the rate of death from nonarrhythmic causes.

Guidelines--for the obedience of fools and the guidance of wise men?

Guidelines for medical management are now part of medical life. A fool--loosely defined as someone who does not know much about a particular area of medicine--will do well to follow guidelines when treating patients, but a wise man (again, loosely defined as someone who does know about the disease in question) might do better not to follow them slavishly. The problem is that the evidence on which guidelines are based is seldom very good. Clinical trials have a variety of problems which often make their relevance to 'real world' medicine dubious. The interpretation of trial results depends heavily on opinion, and a guideline that purports to be evidence based is actually often opinion based. A guideline will depend on the opinions of those who wrote it, and the wise man will use his judgement and give due weight to his own opinions and expertise.

The diagnosis of heart failure in general practice: implications for the UK National Service Framework.

BACKGROUND: The UK National Service Framework recommends patients with suspected heart failure undergo echocardiography. Selection of patients for this investigation in primary care is difficult. It is not clear which clinical features best identify patients with left ventricular systolic dysfunction. AIM: Using echocardiography, to establish the accuracy of primary care diagnosis of left ventricular systolic dysfunction. To investigate the sensitivity, specificity and predictive values of clinical features in the diagnosis of left ventricular systolic dysfunction. STUDY: A cross-sectional study of 621 patients from a population prescribed loop diuretics in 7 general practices. METHOD: Clinical diagnoses were extracted from general practice records. Symptoms, clinical signs, ECG features, brain natriuretic peptide levels and echocardiographic findings were studied in a research clinic. RESULTS: Left ventricular systolic dysfunction (ejection fraction <40%) was present in 50% of 621 patients prescribed loop diuretics in primary care. General practice diagnoses showed high false positive rates. Individual or combinations of clinical features did not accurately predict left ventricular systolic dysfunction. CONCLUSION: These results suggest the clinical diagnosis of left ventricular systolic dysfunction is inaccurate in this population. General practitioners should have a low threshold for referring patients prescribed loop diuretics for echocardiography. Increased open access echocardiography facilities will be needed.

Difficulties of introducing the National Service Framework for heart failure into general practice in the UK.

BACKGROUND: The National Service Framework (NSF) sets standards for the management of heart failure in the UK. Loop diuretics are commonly first prescribed in primary care. Some patients taking these drugs have heart failure and may benefit from other treatments including ACE inhibitors. Accurate diagnosis in primary care is essential for the aims of the NSF to be realised. AIMS: To investigate loop diuretic prescribing in general practice, to analyse recorded clinical features, patient investigations and ACE inhibitor use in this population. METHOD: One thousand three hundred and one patients taking loop diuretics were identified from prescription records of seven general practices. Demographic details, clinical features, investigations and drug treatments were extracted from patient records. RESULTS: The prevalence of loop diuretic prescribing increased with age. Twenty percent of patients were attributed a diagnosis of heart failure but relevant clinical features were recorded in less than 50% of patient records. Open access echocardiography was used in 8.9% of patients. ACE inhibitors were prescribed in 39.8% of patients considered to have heart failure. 18.2% of these were taking the recommended target dose. CONCLUSION: Loop diuretics are prescribed commonly, particularly in the elderly. There is no clear pattern of documented clinical features that leads to prescription of these drugs. Open access echocardiography is rarely used to aid diagnosis. ACE inhibitors are under-prescribed and under-dosed in patients diagnosed with heart failure in this study population.

Evidence-based medicine, opinion-based medicine, and real-world medicine.

The freedom of a doctor to treat an individual patient in the way he believes best has been markedly limited by the concept of evidence-based medicine. Clearly all would wish to practice according to the best available evidence, but it has become accepted that "evidence-based" means that which is derived from randomized, and preferably double-blind, clinical trials. The history of clinical trial development, which can be traced to the use of oranges and lemons for the treatment of scurvy in 1747, has reflected a progressive need to establish whether smaller and smaller effects of treatment are real. It has led to difficult concepts such as "equivalence" and aberrations such as "meta-analysis." An examination of evidence-based practice shows that it has usually been filtered through the opinions of experts and journal editors, and "opinion-based medicine" would be a more appropriate term. In the real world of individual patients with multiple diseases who are receiving a number of different drugs, the practice of evidence-based (or even opinion-based) medicine is extremely difficult. For each patient a judgment has to be made by the clinician of the likely balance of risks and benefits of any therapy. Good practice still requires clinical freedom for doctors.

Assessing exercise capacity, quality of life and haemodynamics in heart failure: do the tests tell us the same thing?

BACKGROUND: The objective measurement of exercise tolerance is an important component of heart failure trials. The use of laboratory-based treadmill exercise testing has attracted criticism, however, as being unrepresentative of patients' true capabilities. AIM: To examine the relationships between tests of exercise capacity, quality of life and haemodynamics in patients with stable symptomatic heart failure. METHODS: Thirty-six patients with mild-moderate chronic heart failure were studied. Exercise capacity was assessed in the laboratory by maximal treadmill tests and self-paced corridor walk tests, and in the patients' homes by hip-borne pedometers. Quality of life was assessed by a disease-specific questionnaire. Cardiac output and limb blood flow were measured by non-invasive techniques. RESULTS: Customary activity as assessed by pedometer scores correlated with quality of life questionnaire scores (r(S) = 0.47, P = 0.04), and both variables correlated with limb (calf) blood flow (pedometer scores: r(S) = 0.39, P = 0.03; quality of life scores: r(S)= 0.50, P = 0.04). The laboratory-based maximal treadmill test correlated with the self-paced corridor walk test, but neither of these tests correlated with pedometer scores, quality of life or haemodynamics. CONCLUSIONS: Different methods of assessing exercise capacity do not appear to give comparable results and bear different relationships to haemodynamic variables and quality of life. Pedometer scores of customary activity may better reflect patients' quality of life and appear to be more closely related to limb blood flow than the maximal treadmill exercise test or the corridor walk test. The sole use of laboratory-based exercise tests in therapeutic trials may give a misleading assessment of treatment efficacy in heart failure patients.