Background and Rationale:

Individuals with heart failure (HF) have severely reduced peak aerobic power (VO_2peak) and abnormal peripheral vascular endothelial function. Previous investigations have shown that heart transplantation (HTX) is associated with an improvement in VO_2peak. However, the effect of HTX on peripheral vascular endothelial function has not been well studied.

Objective:

The aim of this study was to compare VO_2peak and brachial artery endothelial function in clinically stable individuals with HF and HTX recipients.

Methods:

Forty-two HF (NYHA functional class I to III; age (mean +/- SD): 62 +/- 12 years; 76% men) and 31 HTX patients (age: 58 +/- 11 years; 77% men) were recruited for this investigation. VO_2peak, peak heart rate, systolic blood pressure and rate pressure product were obtained during a symptom-limited cycle exercise test. Age-predicted VO2peak was calculated from regression equations for healthy sedentary men and women. Brachial artery endothelial function was measured using the flow-mediated dilation procedure.

Results:

HTX patients had increased VO_2peak (HTX: 1.7 +/- 0.6 vs. HF: 1.4 +/- 0.5 L [middle dot] min^-1, P = 0.019; HTX: 20.6 +/- 7.5 vs. HF: 16.4 +/- 5.8 ml [middle dot] kg^-1 [middle dot] min^-1, P = 0.011), and percent of age-predicted VO_2peak (HTX: 70 +/- 22 vs. HF: 60 +/- 20%, P = 0.044) compared to HF patients. HTX recipients had increased peak heart rate (HTX: 144 +/- 22 vs. HF: 112 +/- 30 bpm, P < 0.001), systolic blood pressure (HTX: 174 +/- 26 vs. HF: 150 +/- 30 mmHg, P = 0.001) and rate pressure product (HTX: 25 +/- 6 vs. HF: 17 +/- 6 bpm [middle dot] mmHg [middle dot] 10³, P < 0.001) compared to individuals with HF. Brachial artery endothelial function was not different between groups (Figure 1).

Figure 1. Endothelial function in individuals with HF and HTX recipients. (all comparisons,

Conclusions:

VO_2peak is increased in HTX recipients compared to HF patients but it remains 30% lower in comparison to healthy sedentary individuals. Reduced VO_2peak in HTX recipients may be secondary to abnormal peripheral vascular endothelial function that remains impaired following HTX. Interventions that improve endothelial function may play an important role in improving the reduced VO_2peak in HTX recipients.

Section Description

For more information, contact Marilyn Thomas (204) 488-5854