Arterial Stiffness and Endothelial Function in Heart Failure

This study is designed as an observational pilot study involving 50 patients (age ≥ 18 years) with a new diagnosis of HF (HFpEF or HFrEF). It is sponsored by Coventry University but will take place at The Cardiology and Cardiac Rehabilitation Departments at University Hospital Coventry and Warwickshire (study site). All study assessments will be scheduled to coincide with participants' routine clinical appointments, ensuring no additional hospital visits are required solely for research purposes.

The study will involve participants attending the clinical research site for three study visits lasting approximately 1.5 hours each:

(i) Visit 1: Baseline visit- at the point of diagnosis. (ii) Visit 2: After completion of initial pharmacologic treatment for HF (usually around 4±2 weeks).

(iii) Visit 3: After completion of cardiac rehabilitation - delivered as part of standard care for HF patients (another 4±2 weeks)

The following assessments will be performed as part of this study:

Baseline (only):

• Collection of demographic details (age, sex, ethnicity, alcohol consumption, and smoking status)
• Collection of previous/existing results from the participants medical records will include the following:
• Medical History: Documented diagnoses, comorbidities, and history of cardiovascular conditions.
• Concomitant Medications: Details of all current prescribed and over-the-counter medications relevant to their clinical care.
• Physical Examination and Vital Signs: Blood pressure, pulse rate, and any other routinely recorded cardiovascular parameters available within their clinical record.

All data will be collected only from information already recorded as part of routine clinical care.

Baseline (Week 0), Visit 2 (Week 4 ± 2), Visit 3 (Week 4 ± 2)

The participant will undergo the study assessments as described below:

Participant will undergo physical examination (Blood pressure and Pulse) and anthropometrics (Body weight, height, and body mass index (BMI)) at each visit.

1. Arterial stiffness, as a measure of arterial function, will be assessed using the non-invasive SphygmoCor device (AtCor Medical Ltd., Australia), which allows for both pulse wave analysis and pulse wave velocity to be performed non-invasively using the gold standard techniques. The measurement is simple and painless, taking only a few minutes to perform. While the participant is in a comfortable supine position, the researcher will place a tonometer (pencil-like sensor) gently against the wrist and will record blood pressure signal from the pulse.
2. Endothelial function, as a measure of vascular health, will be assessed using non-invasive Laser Doppler Flowmetry (LDF) technique, which measures cutaneous microvascular blood flow according to the Fizeau-Doppler principle. Measurements of cutaneous blood flow will be expressed in perfusion units and the Laser Doppler signal will be continuously monitored on a computer (Moor instruments, VMS software V.4.06) coupled with Moor instruments system (moorVMS-VASC). The thenar eminence will be used for the placement of the LDF probe (VP1T/7), consistently at the same place, before and post the occlusive reactive hyperaemia manoeuvre. The room temperature will be maintained at 22°C during forearm cutaneous blood flow measurements. Reactive hyperaemia will be produced by occluding the forearm blood flow with a pneumatic cuff inflated to a pressure of 50 mm Hg above the Systolic blood pressure for 3 min. The signal obtained during complete forearm arterial occlusion will be used to determine the biological zero for cutaneous blood flow. Baseline (resting) flow will be calculated as the average of a stable 6-minute Laser Doppler Flowmetry recording obtained prior to cuff occlusion.
3. Haemodynamic monitoring and Cardiac Output Response to Stress (CORS) test Participants will then be connected to the bioreactance Non-Invasive Cardiac Output Monitor (StarlingSV, Baxter Inc., UK) which we have previously evaluated. The method uses four pairs of electrodes applied at the front side of the upper and lower thorax (similar to ECG). Bioreactance is a novel method for continuous non-invasive cardiac function monitoring and estimates cardiac output by analysing the frequency of relative phase shift of electronic current delivered across the thorax. Measurements will be performed using the protocol we have recently developed. Cardiac output will be evaluated whilst participants are lying on their back with their legs elevated at 45 degrees. This is called passive leg raise assessment. The CORS test will also be performed consisting of three phases: 3-min rest (supine) phase, 3-min challenge (standing) phase, and 3-min stress (exercise step-test) phase.
4. Voice recording Subtle changes in speech pattern have emerged as a tool to risk stratify, diagnose, and monitor cardiovascular conditions. Participants will be seated in a quiet room in the clinical research facility to complete the recording. Participants' voices will be audio recorded for up to five minutes while they read a standardised text aloud, speak freely for a short time, count out loud, and then say specific sounds. The recorder will be started just before patients start to read the text and stopped at the end of the task. Voice will be recorded on a standard digital recorder. However, recordings will be transferred immediately to a secure University owned server as per Coventry University ethics guidelines and procedures and then deleted from the recorder device. The software extracts relevant voice features after low-level acoustic features and sudden impulsive noise have been removed using spectral noise gating and voice processing techniques. Extracted voice features are presented in numerical values and will be stored in a password protected computer for further analysis using machine learning and artificial intelligence.