Low Carotid Mean Flow Velocity: A Noninvasive Marker for Coronary Heart Disease—A Community-Based Study

Background: Coronary heart disease (CHD) remains a leading cause of global mortality, often sharing pathophysiologic pathways with cerebrovascular atherosclerosis. Carotid duplex ultrasonography provides a convenient, noninvasive assessment of both vascular structure and hemodynamics. However, the clinical implications of specific carotid flow velocities for predicting CHD risk have not yet been fully explored. Methods: We conducted a case–control study using two community-based cohort datasets from Taiwan’s northern coastal region, enrolling individuals during two periods: from September 2010 to May 2011 and September 2014 to May 2020. Among 4102 participants aged 40–74 years, 45 were excluded for insufficient Doppler waveforms, leaving 4057 eligible subjects. Of these, 165 individuals with physician-confirmed myocardial infarction or prior coronary intervention/surgery were classified as CHD cases; the remaining 3892 served as controls. Carotid blood flow parameters—peak systolic (PSV), end-diastolic (EDV), and time-average maximal flow velocity (MFV), as well as resistance and pulsatility indices (RIs and PIs)—were determined by color Doppler ultrasound at the bilateral common carotid arteries (CCAs). Associations between these measurements and CHD were evaluated through logistic regression, adjusting for conventional cardiovascular risk factors. Results: Participants diagnosed with CHD exhibited significantly lower carotid flow velocities as well as higher RIs and PIs. After multivariable adjustments, right-sided common carotid artery (CCA) flow velocities have a relatively better predictive capacity than left-sided CCA flow velocities. However, left-sided RIs (adjusted OR per 0.1 increase = 1.41, p = 0.027) and PIs (adjusted OR per 1.0 increase = 1.60, p = 0.037) have better predictive value. Right-sided CCA MFV emerged as an independent predictor of CHD which was the most important (adjusted OR per 5.0 cm/s increase = 0.85; 95% CI: 0.77–0.95, p = 0.0038). As compared to subjects with high MFV (≥44.2 cm/s), the multivariable-adjusted OR of having CHD was significantly elevated for subjects with low MFV (<36.02 cm/s; OR = 1.79; 95% CI: 1.13–2.84, p = 0.013). Combinatory analysis further revealed that individuals with low right MFV, particularly when combined with hypertension, had substantially elevated odds of CHD. Conclusions: Reduced right CCA MFV may serve as a clinically informative signal for the presence of CHD. These findings highlight the potential role of detailed carotid Doppler profiling in refining CHD risk assessment, especially among hypertensive patients. Future prospective investigations are warranted to validate the predictive utility of the MFV for coronary events and to explore whether modifying this parameter through targeted interventions can mitigate cardiovascular risk.