Feasibility of Low Energy Diet in HFpEF and Type 2 Diabetes

Open, Single arm intervention, feasibility study

The aims of the proposed feasibility study are to assess whether a low-energy meal replacement plan (MRP) in patients with HFpEF and T2D:

1. Is acceptable to an older, co-morbid, multi-ethnic population

The secondary objectives are to assess whether a low-energy MRP in patients with HFpEF and T2D may be:

1. associated with improved symptoms
2. likely to lead to favourable cardiovascular reverse remodelling
3. likely to improve functional capacity and quality of life
4. associated with favourable reductions in cardiovascular biomarkers
5. associated with increased physical activity
6. associated with favourable cardiovascular outcomes

All patients will undergo the following assessments at baseline, 12-weeks and 12 months (following MRP):

1. Anthropometry: height, weight, BMI.
2. Haemodynamics: resting heart rate and blood pressure.
3. 6-minute walk test +/- cardiopulmonary exercise test (if able to perform)
4. CMR: contrast enhanced, stress perfusion CMR
5. MLWHFQ
6. WHODAS 2.0 (12-item version)
7. Fasting blood test: full blood count, urea and electrolytes, HbA1c, fasting glucose, BNP, high-sensitivity troponin I, insulin and C-peptide. Plasma (≈35mL) will be stored for future biomarker analysis including metabolomics.
8. Urinalysis for proteinuria and urine protein/creatinine ratio.
9. Body composition; dual-energy X-ray absorptiometry (DEXA) scanning.

12. At the end of the 12-week intervention, participants will be invited to a semi-structured interview to explore qualitative aspects of the study to guide future trial design.

13. At 12 months attendance at cardiac rehabilitation will be reviewed.

The MRP provided by Cambridge Weight Plan® contains \~810 kcal/day (30% protein, 50% carbohydrate, 20% fat). The diet will be stopped, and a maintenance diet re-introduced once 50% excess body weight has been lost, or by 12 weeks, whichever comes first.

Eligibility Criteria:
Inclusion Criteria:

* Established T2D (HbA1c ≥6.5%, duration \>3months)
* Obesity (BMI ≥30 or ≥27 kg/m2 if black/south Asian ethnicity)
* Symptoms limiting exercise capacity in normal daily activities (dyspnoea or fatigue) or an established diagnosis of HF
* Diagnosis of HFpEF in accordance with European Society of Cardiology criteria: LV EF \>50% with objective evidence of cardiac structural or functional alterations (LV hypertrophy (≥12mm); LV mass index ≥115g/m2 for males and ≥95g/m2 for females; E/e' ≥13 and a mean e' septal and lateral wall \<9 cm/s; left atrial volume index \>34mL/m2 or reduced global longitudinal strain (\>-18%); elevated levels of natriuretic peptides (B-type natriuretic peptide \>35pg/mL and/or NT-pro B-type natriuretic peptide \>125pg/mL))

Exclusion Criteria:

* Unwilling to undertake MRP (low energy diet)
* HBa1c \>10%
* Diabetes duration \>12 years
* High-dose insulin requirement: either on full basal-bolus insulin regime or insulin requirement \>1U/kg/day
* Have been on insulin treatment \>10 years
* Current treatment with anti-obesity drugs
* Diagnosed eating disorder or purging
* Weight loss \> 5kg in preceding 3 months (unless related to hospitalisation for HF)
* Absolute contraindications to MRI
* Severe renal impairment eGFR\<30ml/min/m2
* Myocardial infarction within preceding 6 months
* History of substance abuse
* Cancer undergoing active treatment
* Unable to consent due to lack of mental capacity
* Pregnancy/considering pregnancy
* People unable to perform activities of daily living independently or unable attend for clinical appointments without a carer/attendant
* Unable to read/understand English sufficiently to provide informed consent