RT Journal Article SR Electronic T1 Oxygen uptake is slower than heart rate on-kinetics in recent myocardial infarction patients JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P4162 VO 40 IS Suppl 56 A1 Marlus Karsten A1 Laura Neves A1 Thomas Beltrame A1 Audrey Borghi-Silva A1 Piergiuseppe Agostoni A1 Aparecida Catai YR 2012 UL http://erj.ersjournals.com/content/40/Suppl_56/P4162.abstract AB Background: The heart rate (HR) and oxygen uptake (VO2) on-kinetics analysis provides information about the individual response to aerobic exercise, which may be reduced after recent myocardial infarction (MI), mainly due to impairment in the oxygen transport system. Design: to determine whether the HR and VO2 onset dynamics were affected by recent MI, we evaluated the VO2 and HR on-kinetics in three groups of subjects with preserved ventricular (VF) and pulmonary function (PF). Methods: Eight men (49±8 years) with a recent MI (RMI), eleven men (52±7 years) with a late MI (LMI) and ten apparently healthy men (48±9 years) (CG) underwent to PF assessment, ramp cardiopulmonary exercise test (CPX) and two constant workload exercise tests (CWETs) on treadmill at moderate and high workloads, corresponding to 75% and 125% of the gas exchange threshold identified at CPX. VO2 was registered breath-by-breath and analyzed after smoothed by moving averages of 8 respiratory cycles. HR was recorded by digital telemetry system. A monoexponencial fit was applied to analyze VO2 and HR on-transient response to the first 360 seconds of the CWETs. Intragroup and intergroup comparisons were realized (p<0.05). Results: RMI group presented τVO2 slower than τHR at moderate and high workloads. When compared to LMI and CG, RMI presented slower τVO2 at high workload. All groups presented faster τHR and τVO2 at moderate when compared to high workload. Conclusion: Recent uncomplicated MI patients present slowing of τVO2 at aerobic exercise, which suggests impairment of oxygen delivery and extraction mechanisms.