RESUMEN
AIMS: The 6-min walk test is an inexpensive, safe, and easy tool to assess functional capacity in patients with cardiopulmonary diseases including heart failure (HF). There is a lack of reference values, which are a prerequisite for the interpretation of test results in patients. Furthermore, determinants independent of the respective disease need to be considered when interpreting the 6-min walk distance (6MWD). METHODS: The prospective Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression (STAAB) cohort study investigates a representative sample of residents of the City of Würzburg, Germany, aged 30 to 79 years, without a history of HF. Participants underwent detailed clinical and echocardiographic phenotyping as well as a standardized assessment of the 6MWD using a 15-m hallway. RESULTS: In a sample of 2762 participants (51% women, mean age 58 ± 11 years), we identified age and height, but not sex, as determinants of the 6MWD. While a worse metabolic profile showed a negative association with the 6MWD, a better systolic and diastolic function showed a positive association with 6MWD. From a subgroup of 681 individuals without any cardiovascular risk factors (60% women, mean age 52 ± 10 years), we computed age- and height-specific reference percentiles. CONCLUSION: In a representative sample of the general population free from HF, we identified determinants of the 6MWD implying objective physical fitness associated with metabolic health as well as with cardiac structure and function. Furthermore, we derived reference percentiles applicable when using a 15-m hallway.
RESUMEN
AIMS: Agonistic antibodies against neurohumoral receptors can induce cardio-noxious effects by altering the baseline receptor activity. To estimate the prevalence of autoantibodies directed against the beta-1 receptor (b1-AAB) in patients admitted to the hospital for acute heart failure (HF) at (i) baseline and (ii) after 6 months of follow-up (F6) and (iii) after another 12 months of follow-up (i.e. 18 months after index hospitalization), to estimate their prognostic impact on clinical outcome (death or first hospitalization for HF). METHODS AND RESULTS: In 47 patients, b1-AAB were serially determined in serum samples collected at index hospitalization and at 6 months of follow-up (F6) with a flow cytometry-based assay: median age 71 years (quartiles 60, 80), 23 (49%) women, 24 (51%) HF with preserved ejection fraction. Beta1-AAB were detected in three subjects at index hospitalization (6%), and in eight subjects at F6 (17%). There were no differences apparent between patients with and without b1-AAB at F6 with regard to age, sex, type, duration, or main cause of HF. During the 12 month period following F6 (i.e. up to month 18), eight events occurred. Event-free survival was associated with prevalence of b1-AAB at F6. Compared with patients without b1-AAB at F6, age-adjusted Cox regression indicated a higher event risk in patients harbouring b1-AAB, with a hazard ratio of 8.96 (95% confidence interval 1.81-44.50, P = 0.007). CONCLUSIONS: Our results suggest a possible adverse prognostic relevance of b1-AAB in patients with acute HF, but this observation needs to be confirmed in larger patient collectives.