Abstract 14063: Characteristics of Heart Disease Patients Whose Respiratory Rate Increases Ealier Than Usual

Abstract

Background:During a ramp exercise, respiratory rate(RR) does not increase in parallel with ramp slope but increases abruptly at some points. Usually start point of RR increasing is regulated by thorax compliance, but sometimes it increases when pulmonary wedge pressure increased. That is, those who exaggerate respiration earlier than usual has a possibility to be heart failure. In this study, we planned to investigate the characteristics of subjects whose RR increases below anaerobic threshold(AT).

Methods: Consecutive 132 patients with heart disease who performed a cardiopulmonary exercise test(CPX) were enrolled. We divided subjects into two groups according to the relation between RR increasing point(RIP) and AT. RIP was determined that the point where the RR slope abruptly increased during a ramp exercise. Those whose RIP was coincided with AT or above AT were classified into group-A, patients whose RIP was below AT was classified into group-B. Between these two groups, we compared baseline characteristics of the patients.

Results: Twenty one patients whose RIP was not determined were excluded. Between group-A(n=69) and group-B(n=42), there was no significant difference in age, gender and AT intensity(53.4+20.1watt vs. 53.0+15.8 watt). Further, there was no significant difference in peak VO2, peak VO2/HR. However, left ventricular enddiastolic diameter(LVEDd) was significantly larger in group-B(52.0+10.2mm) than group-A(47.8+7.2mm)(p=0.007). LVEF was significantly lower in group-B(53.2+16.5%) than group-A(59.5+14.8%)(p=0.02). Minimum VE/VCO2(33.2+5.6 vs. 34.8+4.0, p=0.05) and VE/VCO2 slope(30.5+7.1 vs. 32.5+4.5, p=0.06) tended to be greater in group-B as comparing with group-A. Percentage of heart failure was greater in group-B(38.1%) than in group-A(17.4%) (p=0.01).

Conclusion: Patients whose respiratory rate abruptly increases during a ramp exercise earlier than usual are revealed to have deteriorated cardiac function and exercise tolerance.