Pick the right cardiac test.
Non-invasive testing for suspected or known CAD: pretest likelihood, exercise ECG, stress echo, SPECT, PET, CMR, CCTA, FFR-CT and calcium score, patient factors, stress preparation, high-risk results and pitfalls.
Reviewed October 2026 · verify against current guidelines
Scope — outpatient and post-ED testing for suspected or known coronary disease. Acute chest pain triage, troponin and disposition: undifferentiated chest pain. Confirmed ACS: ACS. ED scoring: HEART pathway tool.
Cardiac testing · 1 of 6
First decide whether to test.
US pathway: stable chest pain, no known CAD (2021 chest pain)
| Low risk | Use a pretest-probability model to identify low risk; testing can then be deferred (Class 1). If testing is wanted: a calcium score to exclude calcified plaque (Class 2a), or exercise ECG without imaging to exclude ischemia (Class 2a). |
|---|---|
| Intermediate to high risk | CCTA (Class 1, LOE A) or stress imaging with echo, PET or SPECT, or CMR (Class 1, LOE B-R). Exercise ECG is reasonable if the resting ECG is interpretable and the patient can reach at least 5 METs (Class 2a). Where nuclear imaging is chosen, PET over SPECT if available (Class 2a). |
| Choosing | Let local availability and expertise decide between CCTA and stress testing. CCTA is favored under 65 and not on preventive therapy; stress testing at 65 or older (2021 figure notes). |
European: pretest likelihood bands (ESC 2024)
| Estimate | Use the risk-factor-weighted clinical likelihood model: sex, age, symptom features and number of risk factors (Class I). Adjust upward for resting ECG changes, LV dysfunction, ventricular arrhythmia, peripheral artery disease or coronary calcium on an old chest CT (Class I). |
|---|---|
| 5% or less | Very low. Deferring testing should be considered (Class IIa) unless symptoms persist after noncardiac causes are excluded. |
| Above 5% to 15% | Low. A calcium score should be considered to reclassify patients to very low (Class IIa). The benefit of testing is uncertain; it may be done if symptoms are limiting. |
| Above 5% | With symptoms, CCTA or functional imaging is the first test (Class I). Up to 50%, CCTA is the preferred rule-out test (Class I). Above 15% to 85%, functional imaging rules in better and suits questions of ischemia, viability or microvascular disease. |
| Above 85% | Very high. Invasive angiography is recommended (Class I) with very high likelihood, symptoms refractory to GDMT, angina at a low level of exercise or high event risk, with pressure-wire assessment available. |
Why most patients need less
About 85% of people with new symptoms of suspected chronic coronary syndrome sit at 15% likelihood or less (ESC 2024). In the validation cohorts, annual MI or death ran 0.5%, 1.1% and 2.1% for very low, low and moderate likelihood. The model classed 38% as very low, versus 12% with the older ESC pretest table. In acute chest pain the 2021 guideline makes the same point: for low-risk patients, urgent testing is not routinely needed.
Calcium score: where it fits
| Stable, low risk | Reasonable first-line test to exclude calcified plaque (2021, Class 2a). |
|---|---|
| What zero means | A calcium score of zero has a negative predictive value above 95% for obstructive CAD, but it misses more in the young: zero calcium was found in 58% of patients under 40 with obstructive CAD versus 9% of those aged 60 to 69 (ESC 2024). |
| With nuclear imaging | Report the calcium score from the attenuation-correction CT (ESC 2024, Class I); adding it to stress testing can be useful (2021, Class 2a). |
| Acute chest pain | Not a stand-alone ED test: it cannot assess stenosis or noncalcified plaque (2022 ACC pathway). |
Cardiac testing · 2 of 6
Anatomy or ischemia: name the question.
What each test answers
| Exercise ECG | Reasonable as a diagnostic test in the 2021 guideline if the resting ECG is interpretable and the patient can reach at least 5 METs (Class 2a). ESC 2024: recommended for exercise capacity, symptoms, BP response, arrhythmia and event risk (Class I), but as a diagnostic test only when imaging is unavailable (Class IIb). |
|---|---|
| Stress echo | Wall motion with exercise or dobutamine; no radiation, bedside, low cost. May miss ischemia under about 10% of myocardium (ESC 2024). Use ultrasound contrast when 2 or more contiguous segments are not seen (Class I). |
| SPECT MPI | Relative perfusion, scar and LVEF with exercise or a drug stressor. Attenuation correction or prone imaging may reduce false positives (2021, Class 2b). |
| PET MPI | Better accuracy than SPECT and absolute myocardial blood flow; reasonable in preference to SPECT where available (2021, Class 2a; ESC 2024 Class I for SPECT or, preferably, PET). |
| Stress CMR | Perfusion, function and scar without radiation (ESC 2024, Class I). Limited by non-conditional devices, claustrophobia and arrhythmia. |
| CCTA | Plaque and stenosis, obstructive or not. Class 1 for intermediate-to-high risk stable chest pain (2021); Class I first-line at likelihood above 5% to 50% (ESC 2024). In SCOT-HEART, adding CCTA cut 5-year CV death or MI from 3.9% to 2.3% (ESC 2024). |
| FFR-CT | Turns a 40% to 90% proximal or mid stenosis into a vessel-specific ischemia estimate (2021, Class 2a; ESC 2024, Class IIb). No extra contrast, stressor or radiation; needs good images. |
Sequential testing
- Inconclusive or abnormal stress result: CCTA is reasonable (2021, Class 2a).
- Inconclusive CCTA: stress imaging is reasonable (2021, Class 2a). Stenosis of uncertain significance: functional imaging (ESC 2024, Class I).
- Negative stress test but high suspicion: CCTA or invasive angiography may be reasonable (2021, Class 2b).
- Still uncertain after non-invasive testing: invasive angiography with pressure-wire assessment (ESC 2024, Class I).
Cardiac testing · 3 of 6
Fit the test to the patient.
Patient factors
| Can exercise | Exercise is the preferred stressor when possible: it adds exercise capacity (ASE 2020, Class I). Diagnostic exercise ECG needs at least 5 METs (2021). |
|---|---|
| Baseline ECG | Exercise ECG is not diagnostic with abnormal resting ST changes, digoxin, LBBB, WPW pattern or ventricular pacing (2021); ESC 2024 names ST depression of 0.1 mV or more, LBBB or digitalis (Class III). For perfusion imaging with LBBB, pacing or pre-excitation, use a vasodilator, not dobutamine: septal defects mislead (ASNC 2016). |
| Obesity | Image quality falls with echo and CCTA (2021; ESC 2024). PET is particularly recommended in obesity because of its high photon energy (ESC 2024). |
| CKD | CCTA is not recommended with eGFR below 30 (ESC 2024, Class III). Vasodilators and dobutamine carry no renal contraindication, and regadenoson has been used safely in end-stage kidney disease (ASNC 2016). Gadolinium for CMR carries a nephrogenic systemic fibrosis concern in kidney failure (ESC 2024). See contrast. |
| Rate and rhythm | CCTA needs a slow, regular rhythm and breath-holding; fast irregular rhythm is a Class III setting (ESC 2024). ESC 2024 lists beta-blocker or ivabradine for rate control and nitroglycerin for vasodilation as CCTA premedication; a contraindication to either matters (2021). |
| Calcium and age | Extensive calcification degrades CCTA, so stress testing is preferred (2021). In stable chest pain, CCTA is favored under 65 and not on preventive therapy; stress testing is favored at 65 or older (2021). |
| Known CAD | Optimize GDMT before testing (2021, Class 1). Changed symptoms despite GDMT: stress PET or SPECT, CMR or stress echo (2023 CCD, Class 1), with PET preferred to SPECT (Class 2a). CCTA for grafts or stents of 3 mm or more (Class 2a). |
| Young, women | Avoid ionizing radiation where another test answers the question (ESC 2024). Screen for pregnancy before radiation in women of childbearing age (2021). |
Note, October 2026 — stress-lab details below cite ASNC 2016. ASNC published its 2026 stress-testing guideline online on 8 September 2026 (Duvall WL et al., J Nucl Cardiol 2026:102970; PMID 42710612). ASNC says it updates contraindications and "cautionary conditions" and patient preparation, including caffeine avoidance and medication management. Its full text was not available for this review, so items marked ASNC 2016 may be superseded. Doses follow the FDA labels.
Cardiac testing · 4 of 6
Prepare the stress, prevent the failed study.
Preparation
| Caffeine | No methylxanthines (coffee, tea, caffeinated drinks or drugs, aminophylline, theophylline) for at least 12 hours before vasodilator stress (FDA regadenoson label; 2021). They blunt the vasodilator and can produce a false negative (dipyridamole label). Caffeine's half-life is about 5 hours in healthy adults, many patients still have detectable levels after 12 to 24 hours of reported abstinence, and decaffeinated coffee still contains some (ASNC 2016). |
|---|---|
| Dipyridamole | Hold oral dipyridamole, including combination products, for at least 2 days before adenosine or regadenoson (ASNC 2016; regadenoson label). It potentiates adenosine (adenosine label). |
| Beta-blockers | For exercise or dobutamine, they blunt the heart-rate response; holding them helps reach target but may cause hypertension or arrhythmia, and full washout takes 5 half-lives (ASE 2020). Anti-ischemic drugs, beta-blockers included, have been reported to reduce the accuracy of vasodilator stress too (ASNC 2016). Hold or continue per the lab's protocol and the question being asked. |
| Fasting | Nothing to eat for at least 3 hours before pharmacologic stress (ASNC 2016). |
Choosing the stressor
| Regadenoson | Selective A2A agonist. Fixed 0.4 mg IV over up to 10 seconds, 5 mL saline flush, tracer 10 to 20 seconds later. Contraindicated in second- or third-degree AV block or sinus node dysfunction without a working pacemaker. Lowers seizure threshold (label). In 999 patients with asthma or COPD, bronchoconstriction did not differ from placebo but dyspnea was commoner (label; ASNC 2016). |
|---|---|
| Adenosine | Weight-based infusion, 140 mcg/kg/min for 6 minutes; half-life under 10 seconds. Contraindicated in high-grade AV block or sinus node disease without a pacemaker and in bronchospastic lung disease (label). |
| Dipyridamole | 0.142 mg/kg/min over 4 minutes. Longer-acting: have aminophylline ready for bronchospasm or chest pain (label). |
| Reversal | Aminophylline, 50 to 250 mg by slow IV injection, attenuates persistent vasodilator effects (regadenoson and dipyridamole labels). Do not use a methylxanthine for a seizure during stress (regadenoson and adenosine labels). |
| Dobutamine | Preferred with significant reactive airway disease (ASNC 2016). Stages of 3 minutes from 5 to 40 mcg/kg/min, with atropine 0.25 to 0.5 mg steps up to 1 to 2 mg if target heart rate, 85% of age-predicted, is not reached (ASE 2020). Atropine: avoid in narrow-angle glaucoma, myasthenia gravis, obstructive uropathy and obstructive gastrointestinal disorders (2021). Contraindications are in the next table. |
| Any stressor | Contraindicated for every modality: ACS, severe arrhythmia, malignant hypertension, significant LVOT obstruction and symptomatic severe aortic stenosis (ASE 2020). The 2021 guideline also lists, for exercise testing and largely for stress echo: active ACS or acute MI within 2 days, uncontrolled heart failure, significant arrhythmia, severe symptomatic aortic stenosis, severe hypertension (for example 200/110 or more), and acute illness such as acute PE, acute myocarditis or pericarditis, or acute aortic dissection. Suspected ACS goes to the ED, ideally by EMS, not to the stress lab (2021, Class 1). |
Absolute and relative contraindications (ASNC 2016; may be superseded by ASNC 2026)
| Exercise, absolute | High-risk unstable angina; decompensated or poorly controlled heart failure; resting BP above 200/110; uncontrolled arrhythmia; severe symptomatic aortic stenosis; acute PE; acute myocarditis or pericarditis; acute aortic dissection; severe pulmonary hypertension; acute MI within 2 to 4 days; acute symptomatic illness. |
|---|---|
| Exercise, relative | Known significant left main stenosis; asymptomatic severe aortic stenosis; hypertrophic obstructive cardiomyopathy or other severe LVOT obstruction; significant tachy- or bradyarrhythmia; high-degree AV block; electrolyte abnormalities; inability to exercise adequately. With imaging, LBBB, pacing or WPW should preferably have vasodilator stress. |
| Adenosine or regadenoson, absolute | Bronchospasm with ongoing wheezing or significant reactive airway disease; second- or third-degree AV block or sinus node disease without a functioning pacemaker; systolic BP below 90; BP above 200/110; dipyridamole within 48 hours; hypersensitivity; unstable angina, ACS or MI within 2 to 4 days. |
| Adenosine or regadenoson, relative | Profound sinus bradycardia under 40; Mobitz I second-degree AV block; severe aortic stenosis; seizure disorder. For adenosine, caffeine within 12 hours is also listed. |
| Dipyridamole, absolute | Bronchospasm with ongoing wheezing or significant reactive airway disease; systolic BP below 90; BP above 200/110; caffeine within 12 hours; hypersensitivity; unstable angina, ACS or MI within 2 to 4 days. |
| Dipyridamole, relative | Profound sinus bradycardia under 40; second- or third-degree AV block without a functioning pacemaker; severe aortic stenosis; seizure disorder. |
| Dobutamine, absolute | Unstable angina, ACS or MI within 2 to 4 days; significant LVOT obstruction; atrial tachyarrhythmia with uncontrolled rate; prior VT; BP above 200/110; aortic dissection; hypersensitivity. |
| Dobutamine, relative | Beta-blockade blunting the response; severe aortic stenosis; symptomatic or large aortic aneurysm; LBBB; paced ventricular rhythm. |
Cardiac testing · 5 of 6
Read the high-risk result, then act.
High-risk results: US 2021 first, then the ESC 2024 Class I list
| US, CCTA (2021) | Stable chest pain with left main stenosis of 50% or more on CCTA, FFR-CT 0.80 or less, or severe stenosis of 70% or more in all 3 main vessels: invasive angiography guides therapy (Class 1, B-R). |
|---|---|
| ESC, exercise ECG | Duke treadmill score below minus 10. |
| ESC, SPECT or PET | Ischemia in 10% or more of the LV myocardium. |
| ESC, Stress echo | 3 or more of 16 segments with stress-induced hypokinesia or akinesia. |
| ESC, Stress CMR | 2 or more of 16 segments with perfusion defects, or 3 or more dobutamine-induced dysfunctional segments. |
| ESC, CCTA | Left main stenosis 50% or more; three-vessel disease 70% or more; two-vessel disease 70% or more including the proximal LAD; or proximal LAD 70% or more with FFR-CT 0.8 or less. |
| ESC, other markers | Outside the Class I list, the ESC text also counts ST depression at low workload with symptoms, low exercise capacity, complex ventricular ectopy, arrhythmia or abnormal BP response as markers of high cardiac mortality. |
| LV function | LVEF below 50% already means high risk of death (ESC 2024). New LV dysfunction or heart failure in known CCD: invasive angiography (2023 CCD, Class 1). |
What follows
| High risk | Invasive angiography, with FFR or iFR when appropriate, to refine risk and improve symptoms and outcomes (ESC 2024, Class I). Hemodynamic significance is FFR 0.80 or less, or iFR 0.89 or less. |
|---|---|
| Ischemia alone | In ISCHEMIA (5179 patients with moderate-severe ischemia; left main disease, LVEF under 35% and unacceptable angina on medical therapy excluded), routine invasive care did not reduce the composite MACE endpoint at about 3.3 years; angina improved more with invasive care, especially with frequent angina (2023 CCD). Most such patients start with optimized GDMT (ESC 2024). |
| Nonobstructive | Optimize preventive therapy (2021, Class 1). A normal functional test does not uniformly predict annual risk under 1%; a normal CCTA does (2023 CCD). |
| Risk tiers | Annual CV death or MI: low under 1%, intermediate 1% to 3%, high above 3% (2023 CCD, Class 1; ESC 2024 uses the same cut-points for cardiac mortality). |
Cardiac testing · 6 of 6
Radiation, contrast and the usual mistakes.
Radiation and contrast
| No ionizing radiation | Exercise ECG, stress echo, stress CMR. FFR-CT adds none to the CCTA (ESC 2024). |
|---|---|
| Nuclear | PET gives superior images at much lower dose than SPECT. Thallium-201 should be avoided for its higher dose; newer CZT SPECT cameras cut dose and time (ESC 2024). |
| Iodinated contrast | Assess kidney function and contrast allergy before CCTA; preventive measures are recommended below eGFR 30 (ESC 2024). In CCD with CKD, minimize treatment-related AKI (2023 CCD, Class 1). See contrast. |
| Echo and CMR agents | Ultrasound contrast is generally safe; rare anaphylaxis is reported (ESC 2024). Perflutren hypersensitivity is a contraindication (2021). CMR is listed with hemodialysis as a limitation (ESC 2024). |
Appropriate-use pitfalls
- Testing the low-risk patient. No evidence that stress testing or imaging within 30 days improves outcomes after a low-risk ED visit (2021).
- Surveillance testing. Stable CCD with no change on GDMT: routine periodic CCTA or stress testing is Class 3, no benefit; routine LV function checks too; routine angiography is Class 3, harm (2023 CCD).
- Angiography to risk-stratify. Not routine without LV dysfunction, heart failure, refractory angina or suspected left main disease (2023 CCD, Class 3).
- Exercise ECG as the diagnostic test. The standards differ. US 2021: reasonable (Class 2a) if the resting ECG is interpretable and the patient reaches at least 5 METs. ESC 2024: not recommended to rule out CAD at likelihood above 5% to 50% when CCTA or functional imaging is available (Class III). Know which one your service follows.
- CCTA in the wrong body. eGFR below 30, decompensated heart failure, heavy calcium, fast irregular rhythm, severe obesity or no breath-hold (ESC 2024, Class III).
- Repeating a failed modality. After a nondiagnostic study, switch tests (2022 ACC pathway).
- Calcium score in the ED. It cannot see stenosis or soft plaque (2022 ACC pathway).
- Coffee on the day. A methylxanthine within 12 hours can neutralize vasodilator stress.
CAD coronary artery diseaseCCD chronic coronary diseaseCCS chronic coronary syndromeCCTA coronary CT angiographyFFR-CT CT-derived fractional flow reserveiFR instantaneous wave-free ratioMPI myocardial perfusion imagingCMR cardiac magnetic resonanceCZT cadmium-zinc-telluride detectorGDMT guideline-directed medical therapyLVOT left ventricular outflow tractMETs metabolic equivalentsLBBB left bundle branch blockWPW Wolff-Parkinson-WhiteAV atrioventricularVT ventricular tachycardiaCOPD chronic obstructive pulmonary diseaseCKD chronic kidney diseaseFFR fractional flow reserveAKI acute kidney injuryACS acute coronary syndromeLV left ventricleLVEF left ventricular ejection fractionMACE major adverse cardiovascular eventsLAD left anterior descending arteryCV cardiovascularPE pulmonary embolismPET positron emission tomographySPECT single-photon emission CT
Educational reference only — not medical advice. Stress-agent doses restate the US prescribing information and stress-lab guidance for recognition, not ordering; the imaging lab's protocol governs. Verify against the current ACC/AHA, ESC, ASE and ASNC documents and local policy.
Sources
Verify against current guidelines and local protocol before acting.
- Gulati M, Levy PD, Mukherjee D, et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain. Circulation 2021;144(22):e368-e454. doi:10.1161/CIR.0000000000001029. Recommendations, Table 5 and figure footnotes read from the guideline text and the AHA guideline slide set (professional.heart.org).
- Virani SS, Newby LK, Arnold SV, et al. 2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease. Circulation 2023;148(9):e9-e119. doi:10.1161/CIR.0000000000001168. Sections 3.1, 3.2, 6.7 and 7.1.
- Vrints C, Andreotti F, Koskinas KC, et al. 2024 ESC Guidelines for the management of chronic coronary syndromes. Eur Heart J 2024;45(36):3415-3537. doi:10.1093/eurheartj/ehae177. Section 3, Recommendation Tables 3, 5, 8-11, 13 and 14, Table 6.
- Pellikka PA, Arruda-Olson A, Chaudhry FA, et al. Guidelines for performance, interpretation, and application of stress echocardiography in ischemic heart disease: from the American Society of Echocardiography. J Am Soc Echocardiogr 2020;33(1):1-41.e8. doi:10.1016/j.echo.2019.07.001.
- Henzlova MJ, Duvall WL, Einstein AJ, Travin MI, Verberne HJ. ASNC imaging guidelines for SPECT nuclear cardiology procedures: stress, protocols, and tracers. J Nucl Cardiol 2016;23(3):606-639. doi:10.1007/s12350-015-0387-x. Superseded by: Duvall WL, Skali H, Aggarwal NR, et al. 2026 ASNC guideline for stress testing in SPECT and PET myocardial perfusion imaging. J Nucl Cardiol 2026:102970. doi:10.1016/j.nuclcard.2026.102970 (online 8 September 2026). The 2026 full text could not be opened for this review (publisher access blocked); details attributed to ASNC 2016 should be checked against it.
- Regadenoson injection, US prescribing information (Hospira, DailyMed, revised December 2025). Adenosine injection for myocardial perfusion scintigraphy, US prescribing information (NorthStar Rx, DailyMed, February 2025). Dipyridamole injection, US prescribing information (Hikma, DailyMed, August 2026).
- Kontos MC, de Lemos JA, Deitelzweig SB, et al. 2022 ACC Expert Consensus Decision Pathway on the Evaluation and Disposition of Acute Chest Pain in the Emergency Department. J Am Coll Cardiol 2022;80(20):1925-1960. doi:10.1016/j.jacc.2022.08.750.
- Facts restated in our own words; no society tables, figures or algorithms reproduced. Not affiliated with or endorsed by the AHA, ACC, ESC, ASE or ASNC.