Here is the design of a clinical trial:

Official Title: Estimation of Metabolic Abnormalities,Lifestyle Behaviors and Diet Pattern in Adults With Heart Failure

Included conditions:
- Heart Failure
- Metabolic Disease

Study Armgroups:

Interventions:

Primary Outcomes:
- {'measure': 'a composite of cardiovascular mortality or hospitalization due to subjectively and objectively worsening HF', 'description': "An independent committee of experts including three physicians reviews all the death certificates and medical records for adjudicating the death cases and all suspected CVD cases biennially from the index episode, via telephone contacting patients' family members or reviewing medical records and the Hospital Discharge Register data.", 'timeFrame': '5 years'}

Please estimate the sample size based on the assumption: 
5% loss to follow-up, two-sided alpha level of 0.05, >80% power, two-sided Z test
Sample size estimation
        We use data of previous cohort studies of lifestyle behaviours in patients with chronic HF to determine the sample size. The sample size is calculated with the estimate of an 25.9% mortality in patients with HF without alcohol consumption,28 the estimate of an 37% mortality in patients with HF without exercise prescription.29 Assuming a 5% loss to follow-up,30 a two-sided alpha level of 0.05, we calculate that the study will have >80% power to detect a 20% reduction in mortality with a total number of 1500 patients, using the two-sided Z test. If the sample size cannot be fulfilled during the study time frame, the recruitment period will be extended. Sample size calculations are performed using PASS 15 (NCSS, Kaysville, Utah, USA).