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.

OMNI scale perceived exertion at ventilatory breakpoint in children: response normalized

PURPOSE

The Children's OMNI Scale of Perceived Exertion was used to identify a response normalized rating of perceived exertion (RPE)-Overall, RPE-Legs, and RPE-Chest that corresponds to the ventilatory breakpoint (Vpt) in 8- to 12-yr-old female and male children.

METHODS

Subjects were a priori stratified into two fitness groups on the basis of peak oxygen uptake (VO2 peak): average (A) (41.0-49.0 mL x kg(-1) x min(-1); N = 24) and above average (AA) (50.0-58.0 mL x kg(-1) x min(-1); N = 24). Vpt was determined by a progressive cycle ergometer protocol to VO2 peak.

RESULTS

A gender effect was not observed for any descriptive or dependent variable. Mean VO2peak for the A group was 1.72 L x min(-1) and for the AA group 2.04 L x min(-1). Vpt corresponded to 64.0% VO2 peak for A and 74.0% VO2peak for AA. RPE-Overall (mean A and AA, 6.1), RPE-Legs (mean A and AA, 7.2), and RPE-Chest (mean A and AA, 4.5) did not differ between the fitness groups.

CONCLUSION

Findings indicated that undifferentiated and differentiated RPE-Vpt were similar between female and male children who varied in VO2peak and Vpt. A comparatively stable RPE-Vpt for 8- to 12-yr-old children that vary in VO2peak and Vpt indicates a group normalized perceptual response.