This study aims to evaluate the feasibility and diagnostic accuracy of the CART-BP ring-type wearable blood pressure monitoring device in comparison with 24-hour ambulatory blood pressure monitoring (ABPM) in patients with heart failure with reduced ejection fraction (HFrEF, LVEF ≤ 40%). As a multi-center, prospective, exploratory study, 100 patients will be enrolled at two tertiary hospitals in South Korea. The agreement between the two devices in 24-hour mean, daytime, and nighttime blood pressure measurements will be assessed per ISO 81060-2:2018 criteria.

Hypertension is a major risk factor and exacerbating cause of heart failure. Accurate blood pressure monitoring in HFrEF patients is critically important, as reduced left ventricular stroke volume and altered peripheral vascular hemodynamics may affect the accuracy of photoplethysmography (PPG)-based blood pressure measurement.

The CART-BP device uses PPG technology in a ring form factor to enable continuous, non-invasive blood pressure monitoring. This study will simultaneously measure blood pressure using CART-BP and standard 24-hour ABPM over a 24-hour period. Agreement will be assessed using ISO 81060-2:2018 Criteria 1 and 2. An interim analysis will be conducted after 40 participants are enrolled to assess preliminary agreement and determine whether to continue to the full enrollment of 100 participants.

Inclusion Criteria:

1. Age ≥ 19 years (male or female)
2. Diagnosed with heart failure and currently under treatment
3. Left ventricular ejection fraction (LVEF) ≤ 40% confirmed by echocardiography performed within 1 year prior to enrollment
4. Able to undergo both 24-hour ambulatory blood pressure monitoring and ring-type blood pressure measurement
5. Voluntarily provided written informed consent to participate in this clinical study

Exclusion Criteria:

1. Office blood pressure: SBP < 90 mmHg, or DBP < 50 mmHg, or SBP > 180 mmHg, or DBP > 100 mmHg
2. Unable to perform 24-hour ambulatory blood pressure monitoring
3. Unable to wear or use the ring-type blood pressure device
4. Variability in three consecutive resting cuff blood pressure measurements ≥ 20 mmHg (SBP) or ≥ 10 mmHg (DBP)
5. Insufficient valid ABPM readings: < 25 daytime or < 12 nighttime measurements per ESH criteria; or < 25 daytime or < 12 nighttime valid readings from the ring-type device
6. Pregnant, suspected pregnancy, or breastfeeding
7. Judged by the investigator to be legally or mentally unfit to participate in the clinical study

Heart Failure with Reduced Ejection Fraction patients