Abstract 15191: Chronotropic Incompetence: Mechanism of Exercise Intolerance Specific to Patients with Elevated BNP and Preserved Ejection Fraction after Acute Myocardial Infarction?
Background: It remains unknown whether chronotropic incompetence is a specific mechanism of reduced exercise capacity in patients with elevated BNP and preserved left ventricular ejection fraction (LVEF), i.e., diastolic heart failure (DHF).
Methods: Among a total of 1043 consecutive patients with acute myocardial infarction (AMI) who participated in cardiac rehabilitation (CR), those fulfilling the following criteria were selected; LVEF≥40% and BNP<200pg/ml (Normal group, n=425), LVEF≥40% and BNP≥200pg/ml (DHF group, n=105) and LVEF<40% and BNP≥200pg/ml (SHF group, n=127). Chronotropic response index (CRI)<80% was defined as chronotropic incompetence.
Results: Compared with Normal group, both DHF and SHF groups showed significantly lower peak oxygen uptake (PVO2) (Normal 80±14 vs DHF 72±14%, p<0.01; vs SHF 71±13%, p<0.01). Although both DHF and SHF groups showed significantly lower peak HR (Normal 137±24 vs DHF 125±23 vs SHF 131±23bpm) and CRI (Normal 79±25 vs DHF 69±26vs SHF 74±25%) than Normal group (p<0.01), there were no significant differences between DHF and SHF groups. In addition, the prevalence of chronotropic incompetence (Normal 50% vs DHF 74% vs SHF 62%) was higher in DHF group than in Normal group (p<0.01), but not significantly different between DHF and SHF groups. There was significant correlations between PVO2 and CRI in all groups.
Conclusion: Chronotropic incompetence may contribute to exercise intolerance in both DHF and SHF patients after AMI, but is not necessarily specific to DHF.
- © 2011 by American Heart Association, Inc.