You may have heard of a “carotid ultrasound.” But did you know there are actually two different carotid tests — one for stroke risk and one for heart attack risk? And there’s a third test, done during a heart ultrasound, that most doctors don’t even measure.
All three tests are safe (no radiation, no needles, no contrast dye), affordable (typically $100-400), and available now. The equipment exists in every cardiology office. Yet most South Asians have never had them.
Why This Matters for South Asians
The Research: Multiple peer-reviewed studies confirm that South Asians face dramatically elevated cardiovascular risk:
STUDY EVIDENCE: South Asian Cardiovascular Risk
- A 2018 American Heart Association Scientific Statement found that “South Asians have higher proportional mortality rates from ASCVD compared with other Asian groups and non-Hispanic whites.”
- Studies in the US found South Asians have a three times higher risk for cardiovascular disease than the national average.
- Stanford Health Care reports South Asians have a four times greater risk of heart disease than the general population and the highest rate of hospitalization in California for coronary artery disease.
Sources: Circulation 2018; PMC 2022; Stanford Health Care
Standard risk calculators like the Framingham score were developed using data from white Americans. They consistently underestimate heart disease risk in South Asians. We need better screening tools. These three ultrasound tests can help fill that gap.
Test #1: Carotid Doppler Ultrasound (For Stroke Risk)
What It Measures
This test looks for blockages in the carotid arteries — the two large blood vessels on either side of your neck that supply blood to your brain. The ultrasound uses “Doppler” technology to measure blood flow and can detect plaque buildup that narrows the artery, blood flow speed (faster flow means more narrowing), and complete or near-complete blockages.
What It Tells You
This test answers one question: Are you at risk for a stroke? If your carotid artery is significantly blocked (usually 70% or more), you may need surgery or a stent to prevent a stroke.
STUDY EVIDENCE: Carotid Doppler Accuracy
The US Preventive Services Task Force reviewed the evidence and found that carotid duplex ultrasonography (DUS) has sensitivity of 90% and specificity of 94% for detecting 70% or greater stenosis, compared with digital subtraction angiography as the reference standard.
A study in Stroke journal found that by adjustment of velocity criteria, carotid Doppler can achieve 100% specificity or 96% sensitivity for detecting significant stenosis.
Sources: USPSTF Recommendation 2021; Stroke 1996;27:1965-69
The Limitation
This test only finds advanced disease — blockages that have already formed. It does not detect early atherosclerosis before blockages develop. That’s where the next test comes in.
Test #2: Carotid Intima-Media Thickness (CIMT) — For Heart Attack Risk
What It Measures
This test measures the thickness of the artery wall itself — specifically the two inner layers called the intima and media. Using high-resolution ultrasound, the technician measures the combined thickness of these two layers in millimeters. This is usually done at the common carotid artery, about 1-2 cm below where it splits.
What It Tells You
This test answers a different question: Is atherosclerosis developing in your body? The thickness of your carotid artery wall reflects what is happening throughout your entire vascular system — including your heart. A thicker wall means more plaque is building up everywhere.
STUDY EVIDENCE: CIMT Predicts Heart Attacks and Strokes
Meta-Analysis of Multiple Large Studies:
- A systematic review and meta-analysis found that a 1 standard deviation increase in CIMT was predictive for myocardial infarction (HR 1.26, 95% CI 1.20-1.31) and for stroke (HR 1.31, 95% CI 1.26-1.36).
- A 2023 Journal of the American Heart Association meta-analysis found that a 1-SD increase in common carotid artery IMT was associated with future stroke (HR 1.32), MI (HR 1.27), and CVD events (HR 1.30).
UK Biobank Study (29,292 Participants):
- Higher cIMT values (>800 µm) were predictive of increased risk for coronary heart disease (HR: 2.15) and myocardial infarction (HR: 2.46).
Meta-Analysis of 119 Clinical Trials (100,667 Patients):
- A 10 µm/year slower cIMT progression was associated with a relative risk of 0.91 for cardiovascular disease events, proving that reducing CIMT thickness reduces actual heart disease risk.
Sources: Atherosclerosis 2013; JAHA 2023; PMC 2025; Eur Heart J 2020
Professional Guidelines Support CIMT
PROFESSIONAL GUIDELINES: American Society of Echocardiography
The 2008 ASE Consensus Statement endorsed CIMT measurement, noting that “nine published prospective studies, which included at least 1000 asymptomatic participants, have examined CIMT and cardiovascular disease risk. Each study demonstrated that CIMT was significantly associated with risk for myocardial infarction, stroke, death from coronary heart disease, or a combination of these events.”
The ASE recommends CIMT for:
- Individuals with intermediate cardiovascular disease risk (6%-20% 10-year risk)
- Patients with family history of premature cardiovascular disease
- Individuals younger than 60 with severe single risk factor abnormalities
- Women younger than 60 with 2 or more cardiovascular disease risk factors
Source: J Am Soc Echocardiogr 2008;21:93-111
Recent Study from North India
STUDY EVIDENCE: CIMT in North Indian Patients (2025)
A prospective study of 150 North Indian patients at Dr. Ram Manohar Lohiya Institute of Medical Sciences, Lucknow found:
- Patients with significant CAD had mean CIMT of 0.80mm vs 0.69mm in controls (P < 0.001)
- 40% of CAD patients had abnormal CIMT (>0.9mm) vs only 8% of controls
- CIMT significantly correlated with disease severity (P = 0.001)
- Patients with abnormal CIMT were more likely to have triple vessel disease and chronic total occlusions
Source: Heart India 2025;13:182-8. doi:10.4103/heartindia.heartindia_26_25
The Critical Difference: Doppler vs. CIMT
Key Point: If you ask your doctor for a “carotid ultrasound,” you will probably get the Doppler test for stroke risk. That test might come back “normal” even if you have significant early atherosclerosis. You must specifically ask for CIMT — carotid intima-media thickness measurement.
| Feature | Carotid Doppler | CIMT |
|---|---|---|
| Primary purpose | Detect stroke risk | Detect heart attack risk |
| What it measures | Blood flow and blockages | Artery wall thickness |
| Finds disease when… | Already blocking 50%+ of artery | Just beginning to develop |
| Prevention stage | Late – damage already significant | Early – still reversible |
Test #3: Interatrial Septal Thickness (For Hidden Heart Fat)
What It Measures
This test measures the thickness of the wall between the two upper chambers of your heart (the atria). This wall can accumulate fat — and that fat reflects how much dangerous fat surrounds your entire heart.
What It Tells You
This test reveals cardiac adiposity — fat around your heart that directly causes inflammation and atherosclerosis in your coronary arteries. This is different from the fat you can see or pinch. Cardiac fat is visceral fat — the dangerous internal fat that drives metabolic disease.
STUDY EVIDENCE: Interatrial Septal Thickness
2026 Study (115 patients, Heart India):
- Strong correlation between IAS thickness and Gensini score (r = 0.823, P < 0.001)
- ROC curve analysis: area under curve of 0.975 for predicting atherosclerosis
- Optimal cutoff of >6mm yielded 93.15% sensitivity and 97.62% specificity
- After adjusting for age, diabetes, dyslipidemia, and LDL, IAS thickness remained the main independent predictor of atherosclerosis (OR: 339.9, P < 0.001)
2023 Study (200 patients, J Indian Acad Echocardiogr):
- Mean IST was 8.02 ± 3.2 mm in CAD patients
- Age, hypertension, and history of CAD significantly associated with IST
Sources: Heart India 2026; J Indian Acad Echocardiogr Cardiovasc Imaging 2023;7:1-7
Why Most Doctors Don’t Measure It: This is newer research, primarily from Indian investigators. It is not yet part of standard echocardiogram protocols in the United States. Most sonographers do not measure it unless specifically asked.
How to Talk to Your Doctor
Many doctors have not heard of CIMT or interatrial septal thickness. Others may be skeptical of tests not yet in mainstream guidelines. Here is how to have a productive conversation:
For CIMT:
“Doctor, I am South Asian and concerned that standard risk calculators may underestimate my cardiovascular risk. The American Society of Echocardiography has endorsed carotid intima-media thickness measurement for intermediate-risk patients. Given my background, I would like to request this test.”
For Interatrial Septal Thickness:
“I understand I’m scheduled for an echocardiogram. Recent research shows that interatrial septal thickness greater than 6mm is strongly associated with coronary artery disease. Could the sonographer please measure and report this? It only takes a moment using the subcostal view.”
References
- Volgman AS, et al. Atherosclerotic Cardiovascular Disease in South Asians in the United States: Epidemiology, Risk Factors, and Treatments. Circulation. 2018;138:e1-e34.
- Stein JH, et al. Use of carotid ultrasound to identify subclinical vascular disease and evaluate cardiovascular disease risk: a consensus statement from the ASE Carotid IMT Task Force. J Am Soc Echocardiogr. 2008;21:93-111.
- Willeit P, et al. Carotid Intima-Media Thickness Progression as Surrogate Marker for Cardiovascular Risk: Meta-Analysis of 119 Clinical Trials Involving 100,667 Patients. Circulation. 2020;142:621-642.
- UK Biobank Study. Carotid intima-media thickness, cardiovascular disease, and risk factors in 29,000 UK Biobank adults. PMC 2025.
- Shetty AB, et al. Interatrial septal thickness as a marker of atherosclerosis. Heart India. 2026;doi:10.4103/heartindia.heartindia_94_25.
- Balla NV, Maale SR. Interatrial septal thickness as a predictor of the presence and severity of coronary artery disease. J Indian Acad Echocardiogr Cardiovasc Imaging. 2023;7:1-7.
- Jamwal N, et al. Association of carotid intima-media thickness with coronary artery disease severity. Heart India. 2025;13:182-8.
- USPSTF. Asymptomatic Carotid Artery Stenosis: Screening. JAMA. 2021.
- Stanford Health Care. Heart Disease in South Asians. 2022.
10. American Heart Association. Why are South Asians dying of heart disease? MASALA Study. 2023.
The Bottom Line
You do not need to wait for chest pain or a heart attack to find out if you have heart disease. Three simple ultrasound tests — CIMT, carotid Doppler, and interatrial septal thickness — can reveal problems years before symptoms appear.
These tests are safe, affordable, and available today. But most doctors will not offer them unless you ask.
As a South Asian, your risk is higher than standard calculators suggest. You deserve screening tools that account for this reality.
Take this article to your next appointment. Ask the questions. Request the tests. Your heart is worth it.
