IMPORTANCE The presumed proarrhythmic action of caffeine is controversial. Few studies have assessed the effect of high doses of caffeine in patients with heart failure due to left ventricular systolic dysfunction at high risk for ventricular arrhythmias. OBJECTIVE To compare the effect of high-dose caffeine or placebo on the frequency of supraventricular and ventricular arrhythmias, both at rest and during a symptom-limited exercise test. DESIGN, SETTING, AND PARTICIPANTS Double-blinded randomized clinical trial with a crossover design conducted at the heart failure and cardiac transplant clinic of a tertiary-care university hospital. The trial included patients with chronic heart failure with moderate-to-severe systolic dysfunction (left ventricular ejection fraction <45%) and New York Heart Association functional class I to III between March 5, 2013, and October 2, 2015. INTERVENTIONS Caffeine (100 mg) or lactose capsules, in addition to 5 doses of 100 mL decaffeinated coffee at 1-hour intervals, for a total of 500 mg of caffeine or placebo during a 5-hour protocol. After a 1-week washout period, the protocol was repeated. MAIN OUTCOMES AND MEASURES Number and percentage of ventricular and supraventricular premature beats assessed by continuous electrocardiographic monitoring. RESULTS We enrolled 51 patients (37 [74%] male; mean [SD] age, 60.6 [10.9] years) with predominantly moderate-to-severe left ventricular systolic dysfunction (mean [SD] left ventricular ejection fraction, 29% [7%]); 31 [61%] had an implantable cardioverterdefibrillator device. No significant differences between the caffeine and placebo groups were observed in the number of ventricular (185 vs 239 beats, respectively; P = .47) and supraventricular premature beats (6 vs 6 beats, respectively; P = .44), as well as in couplets, bigeminal cycles, or nonsustained tachycardia during continuous electrocardiographic monitoring. Exercise test-derived variables, such as ventricular and supraventricular premature beats, duration of exercise, estimated peak oxygen consumption, and heart rate, were not influenced by caffeine ingestion. We observed no increases in ventricular premature beats (91 vs 223 vs 207 beats, respectively) in patients with higher levels of plasma caffeine concentration compared with lower plasma levels (P = .91) or with the placebo group (P = .74). CONCLUSIONS AND RELEVANCE Acute ingestion of high doses of caffeine did not induce arrhythmias in patients with systolic heart failure and at high risk for ventricular arrhythmias. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT02045992

O ensino médico é extremamente importante na determinação da qualidade técnica dos futuros profissionais. Embora o Brasil apresente legislação específica sobre o tema, observamos discrepâncias no processo de aprendizado, o que, muitas vezes, compromete a formação dos futuros médicos. Além disso, métodos de ensino tradicionais, baseados fundamentalmente no diagnóstico de problemas, são ainda praticados em várias faculdades. Estes métodos relegam preceitos educacionais e, muitas vezes, colocam os estudantes em papel secundário. Nessa perspectiva, apresentamos um promissor método de ensino médico chamado Preceptoria em um Minuto (One-Minute Preceptor), salientando seu papel voltado ao profissional em formação. Destacamos também a importância deste método por permitir o ensino em tempo relativamente limitado, frente à crescente demanda por atendimentos

No abstract