Randomized control trial investigating the influence of coffee on heart rate variability in patients with ST-segment elevation myocardial infarction.

BACKGROUND Cardiac autonomic dysfunction post ST-segment elevation myocardial infarction (STEMI) has been linked to an excess risk of premature cardiovascular morbidity and mortality above those with normal autonomic function post-STEMI. AIM The aim of this study was to evaluate the effect of acute ingestion of coffee on autonomic function and cardiovascular outcomes in patients with acute STEMI. DESIGN Randomized control trial. METHODS We randomized 103 patients with acute STEMI, admitted to our Coronary Care Unit, to receive regular coffee (caffeinated) or de-caffeinated coffee using a randomized controlled double-blinded design. Heart rate variability was assessed 5 days post-STEMI to assess the effect of caffeine on autonomic function. RESULTS In the group randomized to regular coffee, parasympathetic activity increased by up to 96% (P = 0.04) after 5 days. There was no detrimental effect of regular coffee on cardiac rhythm post-STEMI. CONCLUSION Coffee ingestion is associated with an increase in parasympathetic autonomic function immediately post-STEMI. Coffee was found to be safe and not associated with any adverse cardiovascular outcomes in the short term.