Following a heart attack or percutaneous coronary intervention (PCI) procedure (to 'open up' narrowed blood vessels in the heart), patients are encouraged to join a cardiac rehabilitation (CR) programme, which provides health and lifestyle advice to assist recovery and reduce risk of future cardiac events. Whilst NICE recommends that CR should "offer people an individual consultation to discuss diet", access to registered dietitians is limited. Instead, CR patients typically receive general healthy eating guidance. Since approximately 50% of patients decline CR, online tools may improve participation. The University of Reading have developed a web-based application (eNutriCardio) that uses a diet questionnaire to assess the quality ('healthiness') of a user's diet. It provides the user with unique, personalised recommendations of foods to increase/reduce to improve diet quality, which aligns with UK public health dietary advice, and incorporates behaviour change techniques.

This pilot study will investigate whether supplementing the usual NHS CR offering with personalised nutrition advice from eNutriCardio (intervention) has a different impact on diet quality and cardiac risk factors (e.g. weight and blood cholesterol) than the CR offering alone (control) after 12 weeks. 82 post-heart attack or PCI patients will provide a dried blood spot sample and record their typical diet using eNutriCardio before being randomly allocated to the control or intervention group. Both groups will be invited to participate in an NHS CR programme, but only intervention participants will receive nutrition advice from eNutriCardio. After 12 weeks, both groups will repeat the diet questionnaire and blood spot sample at home. A follow-up questionnaire will be completed after a further 8 weeks. Participants may also join an optional focus group to discuss their experiences of CR and eNutriCardio. This study is funded by the Health Innovation Partnership, a collaboration between the University of Reading and RBFT.

Recruitment will end when 82 participants have been recruited or the recruitment end date (29th February 2024) is reached (whichever comes first). Participants will be screened by the experienced RBFT Cardiology Research Team following their admission to hospital for a myocardial infarction or PCI procedure. Immediately after receiving informed consent and completing the screening form, the Cardiology Research Team will direct eligible participants to eNutriCardio and help them to register. After registration, participants will be randomly allocated by eNutriCardio to either the PN intervention or control group:

• PN intervention group: in addition to the usual NHS CR offering, participants will receive web-based delivery of PN advice based on the participant's dietary intake; PN advice will be unique to each participant.
• Control group: participants will receive the usual NHS CR offering without PN advice from eNutriCardio.

Since people are often more motivated to change their diet following a 'health scare', participants will use eNutriCardio during their hospital stay or be asked to do this within 7 days of discharge to ensure their pre-event/pre-surgery diet is captured at baseline (any new 'healthier' dietary regimes would be misrepresentative of their habitual intake).

This proof-of-principle pilot study will be conducted over 20 weeks alongside the usual NHS CR offering:

• Week 0 (baseline; ideally within 7 days of hospital discharge): participants will use eNutriCardio to complete the eNutri FFQ, to provide self-reported anthropometric measurements (height and weight) and demographic information, and to answer questions on behaviour change, physical activity, computer proficiency, and usability of eNutriCardio (via the system usability scale (SUS)). They will also provide a DBS sample. Those randomised to the PN group will also receive PN advice about their diet via eNutriCardio.
• Approximately 10 days after hospital discharge: as part of the usual CR care, participants will be contacted by a CR team to discuss CR. They may choose to join or decline to take part.
• Approximately week 4-8: as part of usual CR care, participants will start their 6-8 week CR programme (unless they have declined).
• Weeks 2, 4 & 8: participants in the PN group only will receive interactive coaching emails to set goals and be reminded of their PN advice.
• Week 12 (end of study): participants in both groups will use eNutriCardio to complete the eNutri FFQ, provide self-reported weight, answer questions on physical activity and behaviour change (repeated from week 0), and provide feedback on the CR offering and dietary advice received during the study (e.g. from CR and/or eNutriCardio). They will also provide a second DBS sample.
• Week 20 follow-up: participants in both groups will complete a short online questionnaire about the longer-term effects of the dietary advice received during the study.
• Focus group: after completing the study, 8-10 participants in each group will be invited to participate in an optional focus group at the University of Reading to discuss the dietary advice in more detail.

Pre-screening inclusion criteria (i.e. before patient is approached on the ward):

• Adult patients admitted to RBH following MI or elective PCI procedures
• Eligible to take part in an NHS CR programme run by RBFT or Berkshire Healthcare NHS Trust (identified as living in eligible postcode areas).

Screening inclusion criteria (i.e. screening following the consent process):

• Able to understand verbal and written English without difficulties.
• Able to access eNutriCardio from their usual location (e.g. home): will have access to a suitable device (laptop, computer, tablet or smartphone) AND access to the internet .
• Have an active email address.

Focus group inclusion criteria:

• Request to be contacted about the focus group
• Complete the eNutriCardio questionnaires during week 12
• Take part in an NHS Cardiac Rehabilitation programme
• Can visit the UoR for approximately 1 to 1½ hours
• Able and willing to contribute to a group discussion speaking in English
• Willing to be audio and video recorded
• Other inclusion criteria will already be identified through participation in the pilot study e.g. 18 years and older, able to read and understand English, do not have a dementia or another condition affecting memory

Pre-screening exclusion criteria:

• Diagnosed with dementia or other conditions affecting memory.
• Diagnosed with diabetes (any type).

Screening exclusion criteria:

• Patients unable to give informed consent.
• Pregnant, lactating or planning a pregnancy within the next 5 months.
• Food allergies to dairy, nuts/seeds and/or fish/shellfish.
• Medical conditions/treatments that have a considerable impact on an individual's diet/appetite on a day-to-day basis (e.g. severe gastrointestinal disorders, receiving chemotherapy treatment).
• Usually eat on fewer than 2 occasions per day.
• Receiving dietary advice from a dietitian, nutritionist or medical professional or plan to do so within the next 5 months.
• Following a restrictive diet, such as a vegan diet, meal replacement shake/juice diet (e.g. SlimFast), intermittent fasting diet (e.g. 5:2), very low carbohydrate diet (e.g. keto, Atkins) or any "fad"/"celebrity" diet, or plan to do so within the next 5 months; vegetarians can take part.
• Following a weight-loss programme, such as Weight Watchers, Noom, LighterLife and Slimming World, or plan to do so within the next 5 months; those aiming to lose weight through general healthy eating and "cutting down" without following specialised weight loss advice can take part.
• Taking weight-loss medication (prescribed or over the counter) or plan to do so within the next 5 months.
• Visual and/or physical impairments that prevent an individual from interacting with visual elements on the screen on their device/using their device, such as clicking buttons/mouse or using the touch pad or viewing images.
• Taking part in another research study.

We plan to share anonymised individual participant data that underlie results in publications in a public repository. Sharing of IPD will be in line with the confidentiality and consent agreements. This may include:

• Sociodemographics
• Anthropometrics
• Dietary intake data
• Blood biomarkers

No later than the time of first publication and available indefinitely thereafter.

We plan for open access.

Due to the nature of the study, the participants and researchers will be unblinded. Although the participants will not be explicitly told which group they are in, they will become aware of their group after completing the eNutriCardio FFQ at baseline. Those randomised to the intervention group will receive their eNutriCardio PN advice and those randomised to the control group will not receive any PN advice from eNutriCardio and therefore know which group they have been allocated to.