Ischemic Heart Disease Investigation: Complete 2026 Doctor’s Diagnostic Guide

By Dr. Sagar Rajkuwar, ENT Specialist, Nashik, Maharashtra, India
🌐 www.entspecialistinnashik.com

Short answer: Modern ischemic heart disease investigation follows a stepwise diagnostic pathway: (1) focused history and examination with risk-score assessment, (2) resting 12-lead ECG, (3) baseline bloods — lipid profile, HbA1c, Lipoprotein(a), hs-CRP, high-sensitivity troponin, renal function, (4) non-invasive imaging — echocardiography, coronary artery calcium (CAC) score, CT coronary angiography (CCTA), (5) functional testing — stress ECG, stress echocardiography, SPECT/PET myocardial perfusion imaging, cardiac MRI with vasodilator stress, and (6) invasive coronary angiography with FFR, iFR, IVUS, or OCT when needed. If you are reading about ischemic heart disease investigation, this 2026 ENT-authored guide — built on WHO, CDC, NHS, AHA/ACC/SCAI 2021, and ESC 2024 Chronic Coronary Syndromes — walks you through every test.

Table of Contents

1. Introduction
2. Step 1 — History & Risk Score
3. Step 2 — Resting 12-Lead ECG
4. Step 3 — Blood Tests & Biomarkers
5. Step 4 — Resting Echocardiography
6. Step 5 — CAC Score & CT Coronary Angiography
7. Step 6 — Functional (Stress) Testing
8. Step 7 — Cardiac MRI
9. Step 8 — Invasive Coronary Angiography
10. Functional Assessment During Angiography: FFR, iFR, CFR, IMR
11. Intracoronary Imaging: IVUS & OCT
12. Investigation of Vasospastic & Microvascular Angina
13. Investigation After an MI
14. Investigation in Special Groups
15. Choosing the Right Test — ESC 2024 Pathway
16. External Video Resource
17. FAQs
18. Conclusion
19. References

1. Introduction

Ischaemic heart disease (IHD), also called coronary artery disease (CAD), is the global leader among causes of death. Accurate ischemic heart disease investigation is critical to pick the right patients for lifestyle, medication, PCI, or CABG while avoiding over-testing and over-treatment.

2. Step 1 — History & Risk Score

2.1 Clinical history

• Character of chest pain (pressure/tightness/burning)
• Triggers (exertion, cold, emotion, heavy meals)
• Duration, radiation, associated breathlessness, sweating, nausea
• Risk factors — age, sex, family history, hypertension, diabetes, dyslipidaemia, smoking
• Comorbidities — CKD, autoimmune disease, prior pregnancy complications

2.2 Pre-test probability tools

• Diamond–Forrester and ESC 2024 CAD Consortium scores
• ASCVD risk calculator (ACC/AHA)
• SCORE2 (ESC)
• QRISK3 (NHS)
• Framingham Risk Score

3. Step 2 — Resting 12-Lead ECG

• Baseline for every suspected CAD patient
• Features: ST-depression, T-wave inversion, pathological Q-waves, LVH, LBBB
• A normal resting ECG does not exclude CAD
• Compare serial ECGs for dynamic changes

This is the cheapest and fastest step in ischemic heart disease investigation.

4. Step 3 — Blood Tests & Biomarkers

• Fasting lipid profile (total, LDL, HDL, triglycerides)
• Lipoprotein(a) — once in a lifetime per ESC 2024
• Apolipoprotein B for refined risk assessment
• Fasting glucose, HbA1c
• Renal function (eGFR, creatinine)
• Thyroid function if symptoms warrant
• Full blood count — anaemia can precipitate ischaemia
• High-sensitivity troponin I/T — gold-standard for MI diagnosis
• hs-CRP — residual inflammatory risk
• NT-proBNP — heart failure assessment

5. Step 4 — Resting Echocardiography

• Left ventricular ejection fraction (LVEF)
• Regional wall-motion abnormalities
• Diastolic function
• Valve disease
• Pericardial effusion
• Right ventricular function

6. Step 5 — CAC Score & CT Coronary Angiography

6.1 Coronary artery calcium (CAC) score

• Non-contrast CT; low radiation
• CAC = 0 confers very low 10-year risk
• CAC >100 or ≥75th percentile upgrades risk category
• Used in intermediate-risk primary prevention

6.2 CT coronary angiography (CCTA)

• First-line test for symptomatic stable CAD per ESC 2024
• Shows plaque anatomy, degree of stenosis, high-risk plaque features
• Negative predictive value >95%
• Can be combined with CT-FFR for functional assessment non-invasively

7. Step 6 — Functional (Stress) Testing

7.1 Exercise ECG (Treadmill Test)

• Classic, cheap, widely available
• ≥1 mm horizontal/downsloping ST-depression → positive
• Lower sensitivity in women & those with abnormal baseline ECG

7.2 Stress echocardiography

• Exercise or dobutamine stress
• Detects new wall-motion abnormalities
• Sensitivity 85%, specificity 85%

7.3 SPECT / PET myocardial perfusion imaging

• Technetium-99m or thallium-201 (SPECT)
• Rubidium-82 or N-13 ammonia (PET)
• Quantifies ischaemic burden
• PET also assesses viability and myocardial blood flow

7.4 Stress CMR

• Vasodilator (adenosine/regadenoson) stress perfusion CMR
• Detects subendocardial ischaemia
• Simultaneous viability, scar, function
• No radiation

8. Step 7 — Cardiac MRI

• Gold-standard for LV function and tissue characterisation
• Late gadolinium enhancement — scar, viability
• T1/T2 mapping — oedema, iron overload, amyloid
• Essential for MINOCA workup (Takotsubo, myocarditis, SCAD)

9. Step 8 — Invasive Coronary Angiography

• Gold standard for anatomy
• Radial-first approach reduces bleeding
• Indications: STEMI, high-risk NSTEMI, high clinical suspicion with non-invasive imaging ambiguity, refractory angina, prior CABG dysfunction
• SYNTAX score calculated for revascularisation planning

10. Functional Assessment During Angiography: FFR, iFR, CFR, IMR

• FFR ≤0.80 → treat
• iFR ≤0.89 → treat (no adenosine required)
• FFR 0.81–0.90 → further assessment
• Coronary flow reserve (CFR) <2.0 → microvascular dysfunction
• Index of microcirculatory resistance (IMR) >25 → microvascular dysfunction
• FAME, FAME-2 trials showed FFR-guided PCI reduces events

11. Intracoronary Imaging: IVUS & OCT

• Intravascular ultrasound (IVUS) — plaque burden, stent sizing, apposition
• Optical coherence tomography (OCT) — higher resolution; detects thin-cap fibroatheroma, dissection, stent malapposition
• Important in left-main PCI, in-stent restenosis, calcified lesions

12. Investigation of Vasospastic & Microvascular Angina

• Normal coronaries on angiography with angina → think INOCA/ANOCA
• Acetylcholine provocation test for vasospasm
• CFR & IMR for microvascular dysfunction
• Cardiac PET for myocardial blood flow quantification

13. Investigation After an MI

• Serial ECG, troponin
• Echocardiography — LVEF, wall motion, complications (VSR, papillary muscle rupture, pericardial effusion)
• Coronary angiography
• Cardiac MRI if MINOCA suspected
• Risk-stratification before discharge; cardiac rehabilitation enrolment

14. Investigation in Special Groups

• Women: higher microvascular angina — add provocation testing when angiography is non-obstructive
• Diabetics: silent ischaemia common — low threshold for stress or imaging testing
• Elderly / frail: tailor radiation and contrast exposure
• Chronic kidney disease: prefer contrast-sparing modalities (stress CMR, SPECT) or iso-osmolar contrast with hydration
• Pregnancy: minimise radiation; echocardiography, CMR preferred
• Post-cancer: cardio-oncology input; higher CAD risk after chest radiotherapy or anthracyclines

15. Choosing the Right Test — ESC 2024 Pathway

• Low pre-test probability — rarely need imaging
• Intermediate pre-test probability — CCTA first-line
• High pre-test probability — invasive coronary angiography
• Already known CAD with symptoms — stress imaging (MPI/CMR/stress-echo) or invasive angiography depending on severity
• Suspected microvascular disease — functional invasive assessment

This evidence-based pathway is central to modern ischemic heart disease investigation.

16. External Video Resource

Watch a 10-minute explainer on ischemic heart disease investigation:

YouTube: IHD Investigation Pathway – AHA / BHF / ESC

17. FAQs

Q1. Is an ECG enough to diagnose IHD?

No — a normal ECG does not exclude IHD. Further testing is often needed.

Q2. What is the best non-invasive test?

CT coronary angiography is first-line for stable symptomatic patients per ESC 2024.

Q3. How often should Lp(a) be measured?

Once in a lifetime per ESC 2024, unless on specific Lp(a)-lowering therapy.

Q4. Can troponin diagnose chronic IHD?

No — troponin confirms acute myocardial injury. Mild chronic elevations may indicate structural disease.

Q5. Who needs a CAC score?

Intermediate-risk primary-prevention adults 40–75 years for refined risk stratification.

Q6. What is FFR?

Fractional Flow Reserve — a pressure-wire measurement during angiography; ≤0.80 indicates functional significance.

Q7. Is MRI better than CT for CAD?

CT is better for anatomy; MRI is better for function, scar and myocarditis.

Q8. Can smartwatches investigate IHD?

They can suggest arrhythmia; they cannot replace diagnostic cardiac testing.

18. Conclusion

The modern approach to ischemic heart disease investigation is stepwise, pre-test-probability-driven, and personalised. From a thorough history and resting ECG to CT coronary angiography, functional stress imaging, invasive angiography with FFR/iFR, and intracoronary imaging with IVUS/OCT — each test adds value only when the result will change management. Combined with careful lipid, inflammatory, and metabolic biomarker assessment, this pathway identifies patients who truly need revascularisation and spares others from unnecessary invasive procedures.

19. References

1. Vrints C, et al. 2024 ESC Guidelines on Chronic Coronary Syndromes.
2. Lawton JS, et al. 2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularisation.
3. Thygesen K, et al. Fourth Universal Definition of MI. Circulation 2018; updated 2023.
4. Grundy SM, et al. 2018 AHA/ACC Cholesterol Guideline (updated 2023).
5. Pellikka PA, et al. Stress Echocardiography — ASE 2020 Guidelines.
6. Taqueti VR, et al. Coronary microvascular dysfunction. NEJM 2018; 2024 update.
7. WHO Cardiovascular Diseases Fact Sheet 2024.
8. NHS UK Coronary heart disease overview 2024.

📞 ENT Consultation & Surgery

Dr. Sagar Rajkuwar (MS-ENT)
Prabha ENT Clinic, Ambad, Nashik
📱 7387590194 | 9892596635
🌐 www.entspecialistinnashik.com

Medical Disclaimer

Medical Disclaimer: This article is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Audiogram results should be interpreted by a qualified audiologist or ENT specialist. If you have sudden hearing loss, severe dizziness, ear discharge, or other concerning symptoms, seek medical evaluation promptly. Always consult a qualified cardiologist for individualised cardiac investigation.