Clinical determinants of poor six-minute walk test performance in patients with left ventricular systolic dysfunction and no major structural heart disease.

BACKGROUND: The clinical determinants of six-minute walk test (6-MWT) performance in patients with left ventricular systolic dysfunction (LVSD) have rarely been investigated, and it is not clear whether they differ from patients referred for the assessment of symptoms of heart failure who do not have major structural heart disease (MSHD). METHODS AND RESULTS: 571 patients with LVSD enrolled in a chronic disease management programme (79% male; mean age 71+/-10 years; BMI 28+/-5) completed a 6-MWT with a mean distance 337+/-103 m. 688 patients referred with suspected heart failure but in whom MSHD was excluded (49% male; mean age 70+/-11 years; BMI 28+/-6) had a mean 6-MWT distance of 391+/-106 m (P<0.001 compared to patients with LVSD). Relationships with walking distance were determined by calculating odds ratios (ORs) with 95% confidence intervals (CIs) for walking300 m. In patients with LVSD, predictors of poor walking distance (or=75 years (OR=4.0, 95% CI=2.4-6.4); low BMI (<20) (OR=3.4, 95% CI=1.6-7.3); anaemia (OR=2.8, 95% CI=1.8-4.2); resting heart rate>80 beats x min(-1) (OR=2.2, 95% CI=1.3-3.5); and being female (OR=2.0, 95% CI=1.3-3.0). Serum creatinine and NT-proBNP showed dose-response effects, as did self-perceived feelings of depression and anxiety. Determinants of 6-MWT in patients without MSHD were similar including age>or=75 years (OR=6.0, 95% CI=3.4-10.4), anaemia (OR=2.8, 95% CI=1.6-4.9), resting HR>80 beats x min(-1) (OR=2.5, 95% CI=1.4-4.4) and being female (OR=1.6, 95% CI=1.9-2.4). NT-proBNP and self-perceived feelings of depression and anxiety also showed dose-response effects. CONCLUSION: The determinants of poor 6-MWT performance depend on physical-cardiovascular and non-cardiovascular, and psychological factors. Clinical predictors for poor walking performance are similar for patients with LVSD and without MSHD.

Stimulus satiation: effects of repeated exposure to foods on pleasantness and intake.

Frequent and repeated exposure to foods produces stimulus satiation or monotony. To explore further the nature of stimulus satiation, two experiments were conducted. Experiment 1 investigated the influence of initial pleasantness and frequency of intake on monotony. Tests showed that bread and butter was eaten more frequently but was liked less than chocolate. Therefore, normal-weight, healthy males were randomly assigned to either a chocolate condition (CC, N=13) or bread and butter condition (BC, N=16). All subjects received fixed amounts of the assigned food (67g/1473kJ of chocolate or 95g/1355kJ of bread and butter) every day for 22 days. On days 1, 8, 15 and 22 subjects consumed this food ad libitum. Pleasantness of taste and desire to eat chocolate declined significantly over time but no such changes were observed for bread and butter. Experiment 2 examined intake, pleasantness and desire to eat chocolate in 53 subjects over a 15 day period, with 3 conditions: control (CS: N=15), fixed (FS: N=20) and variable (VS: N=18). CS received no chocolate except on test days (days 1, 8 and 15), FS received 67g/1473kJ of chocolate daily and VS received increasing amounts of chocolate from 57g/1251kJ on day 1 to 86g/1888kJ by day 12. Pleasantness and desire to eat chocolate declined over time with this being more pronounced for F and V subjects. However, ad libitum intake increased over time. Both experiments demonstrated significant changes in pleasantness and desire to eat chocolate, but no commensurate decline in intake. Thus, although stimulus satiation occurred for subjective ratings of pleasantness and desire to eat chocolate, intake remained unaffected. This apparent dissociation between pleasantness and intake may reflect different processes underlying liking and wanting.

The influence of phosphatidylserine supplementation on mood and heart rate when faced with an acute stressor.

There have been previous reports that supplements of phosphatidylserine (PS) blunted the release of cortisol in response to exercise stress and that it improved mood. The present study extended these observations by considering whether PS supplementation influenced subjective feelings of stress and the change in heart rate when a stressful mental arithmetic task was performed. In young adults, with neuroticism scores above rather than below the median, the taking of 300mg PS each day for a month was associated with feeling less stressed and having a better mood. The study for the first time reports an improvement in mood following PS supplementation in a sub-group of young healthy adults.