Cardiac imaging and stress testing

• Cardiac imaging is chosen by asking what question needs answering: heart structure and function, inducible myocardial ischaemia, myocardial viability, coronary anatomy, or a mix of these.
• Resting transthoracic echocardiography is the first imaging test in most patients because it is safe, inexpensive, and answers structural questions quickly.
• Exercise electrocardiography is still used when the ECG is interpretable and the patient can exercise, but it is less sensitive than imaging tests.
• Stress echocardiography and nuclear myocardial perfusion imaging detect inducible ischaemia; SPECT gives strong prognostic data but irradiates, while PET can quantify absolute myocardial blood flow.
• Coronary CT angiography is preferred when the question is anatomic, particularly in intermediate-risk patients, but it needs iodinated contrast and a slow, regular heart rate.
• Cardiac MRI gives high-resolution structure, function and tissue characterisation without ionising radiation and is particularly useful for myocardial viability, infiltrative disease and younger patients.

By the end of this page you should be able to:

1. Explain how ultrasound, ECG stress testing, stress echocardiography, SPECT/PET, coronary CT and cardiac MRI each measure a different aspect of cardiac disease.
2. Choose an initial noninvasive cardiac test based on pretest likelihood, symptoms, patient characteristics and local availability.
3. Describe exercise and pharmacologic stress protocols, including target heart rate, endpoints and common contraindications.
4. State the advantages and limitations of SPECT, PET, CCTA and cardiac MRI, including radiation, contrast and gadolinium considerations.
5. Outline the practical aspects of patient preparation, consent, monitoring and complications for these tests.
6. Recognise when a negative test is reassuring, when a second test is needed, and when the patient should proceed to invasive coronary angiography.

Cardiac imaging and stress testing answer questions that bedside assessment and the ECG cannot. Blood flow limitation from coronary atheroma is a dynamic problem: an artery may be narrowed enough to block blood flow during exertion, when myocardial oxygen demand rises, while flow at rest is adequate. Functional tests reproduce that demand and look for ischaemic clues in the ECG, heart wall motion, perfusion or symptoms. Anatomic tests, especially coronary computed tomography angiography, look directly at the lumen and plaque. Echocardiography measures structure and pump function but does not, on its own, prove coronary disease.

This topic is a procedure topic, so later sections organise the work by test rather than by disease. Safety, documentation and escalation principles apply to all of them: select, prepare, monitor, interpret, document, and act on the result.

No single test suits every patient. Contemporary guidelines therefore ask three questions in order: what is the pretest likelihood of obstructive coronary artery disease, what is the question being asked (anatomy, function, viability), and what can this patient and this department actually do safely? Newer guidelines also separate atherosclerotic from microvascular angina, because normal coronary arteries on CT do not exclude angina from coronary microvascular disease or vasospasm. That distinction is frequent enough in clinic practice to matter ^[8].

Transthoracic echocardiography (TTE) uses a piezoelectric ultrasound probe to send brief pulses, usually of 2 to 5 MHz frequency, through the chest wall and to build images from the reflected sound. It is the primary noninvasive modality for anatomic and functional cardiac assessment ^[6]. The principle is simple: the better the resolution, the less the penetration, so the image quality depends on choosing the right frequency and the right acoustic window.

A comprehensive TTE evaluates:

• Left and right ventricular size, wall thickness and global and regional contractile function (ejection fraction is measured by the Simpson rule in apical four-chamber and two-chamber views).
• Valvular structure and function, including grading of stenosis and regurgitation.
• Diastolic function and filling pressure, with parameters such as E/e' ratio; an E/e' ratio of 13 or more indicates diastolic dysfunction with increased filling pressure. ^[6]
• Pulmonary pressures, chamber dimensions, pericardial fluid and aortic root size.
• Additional structural findings, such as clots, vegetations and cardiac masses, where ultrasound characteristics and contrast behaviour can narrow the differential.

Color, pulsed and continuous-wave Doppler sit on top of two-dimensional images to estimate flow velocity and direction. Contrast microbubbles can improve endocardial border definition when acoustic windows are poor, which is particularly helpful during stress ^[2]. Standard adult TTE usually takes about 30 minutes, and longer when advanced techniques are added ^[6].

Guidelines recommend resting echocardiography in the initial evaluation of suspected chronic coronary syndrome to exclude left ventricular dysfunction and valvular disease and to provide structural information for risk stratification. The AHA/ACC framework also recommends a bedside TTE for intermediate-risk patients for the same reason, particularly when there is evidence of Q waves, heart failure, complex arrhythmia or a murmur ^[3]. Resting echocardiography is not accepted by either AHA/ACC or ESC as the sole test to diagnose stable coronary artery disease, although it is used in almost every patient ^[3].

Echocardiography is operator dependent, and acoustic windows can be limited by obesity, chronic lung disease, chest wall deformity or mechanical ventilation. It does not visualise coronary anatomy directly, and a normal resting scan does not rule out coronary disease. When transthoracic windows are inadequate, or the question involves posterior structures such as the aortic arch, valve prostheses or the atrial appendage, transoesophageal echocardiography is the natural escalation.

Transoesophageal echocardiography (TEE) places a multiplanar probe in the oesophagus, behind the heart, and avoids interference from the lungs. TTE and TEE are complementary rather than competing techniques ^[7].

Primary indications include:

• Assessment of a cardiac source of embolism
• Suspected infective endocarditis, especially with prosthetic valves
• Suspected prosthetic valve dysfunction
• Assessment of the thoracic aorta and other vessels
• Assessment of mitral regurgitation or prior to valvular repair
• Intraoperative monitoring of cardiac or percutaneous interventions
• A non-diagnostic TTE, particularly after cardiac surgery

A 30 to 35 centimetre advancement reaches the lower oesophagus, while a 35 to 40 centimetre advancement is used for transgastric views ^[7] (these are approximate probe depths, not patient measurements to be documented as targets).

Practical points: the patient must fast; the probe requires sedation for tolerability; serious complications are very rare but include oesophageal perforation, massive bleeding, arrhythmia and, in aortic dissection, rupture under hypertension ^[7]. Recovery monitoring and a 1.5 to 2 hour observation after sedation are standard in the reported protocol ^[7].

Exercise ECG testing asks one physiological question: can the coronary circulation keep up when myocardial oxygen demand is raised by exercise? The patient walks on a treadmill or cycles while ECG, blood pressure and symptoms are monitored. It is one of the cheapest, fastest and most available tests and remains valuable for functional capacity and prognosis.

The Bruce protocol is used most often worldwide. It has seven stages of three minutes each, a starting speed of 1.7 miles per hour at a 10 percent grade, which costs about 4 metabolic equivalents of task (METS), and workload rises with each stage. A modified Bruce protocol helps less able patients. ^[1]

The stress endpoint is usually 85 percent of the age-predicted maximum heart rate, calculated as 220 minus age ^[1]. A satisfactory result also depends on workload. Less than 5 METS is poor, 5 to 8 METS fair, 9 to 11 METS good and 12 METS or more excellent ^[1]. A Bruce exercise time of under 6 minutes, or failure to reach 85 percent of target heart rate, carries a worse prognosis, with a 5 year survival between 50 and 72 percent in the reported cohort, whereas reaching more than 10 METS predicts an excellent prognosis even when coronary disease is known ^[1]. ^[2]

The stress ECG is usually interpreted as follows ^[1]:

• Read ST segments 60 to 80 milliseconds after the J point.
• Positive for ischaemia if any of: 2 mm or more rapidly upsloping ST depression with slope more than 1 mV per second; 1.5 mm or more slowly upsloping (less than 1 mV per second); 1 mm or more horizontal or downsloping depression.
• An exercise test is also considered positive if there is symptomatic chest pain, high arrhythmia burden or abnormal blood pressure response.
• Failure to reach 85 percent of target heart rate produces a nondiagnostic test rather than a negative one.

The overall sensitivity of exercise ECG for anatomic coronary disease is reported around 46 to 69 percent in modern comparisons, with specificity around 54 to 69 percent, while older pooled cohorts report 60 to 70 percent sensitivity and 85 percent specificity ^[1][3]. Around 1 in 2500 tests is complicated by myocardial infarction or death, so the setting must have resuscitation capability ^[1].

Common indications include suspected angina, post-myocardial infarction risk stratification, assessment of functional capacity and prognosis, and evaluation of arrhythmias ^[1]. Absolute contraindications include acute myocardial infarction within a few days, unstable angina not previously stabilised, severe symptomatic left ventricular dysfunction, life-threatening dysrhythmia, acute pericarditis or myocarditis, acute aortic dissection and, practically, marked hypertension. Relative contraindications include severe aortic stenosis, outflow obstruction, significant valvular stenosis, left main disease, uncontrolled hypertension above 200 over 110 mmHg, electrolyte abnormalities and inability to exercise ^[1].

Other interpretation details matter in routine practice ^[1]:

• Beta blockers blunt heart rate response and reduce accuracy; withdraw rate-slowing drugs 48 hours beforehand if medically safe (the stress-echo protocol), but never precipitate rebound. ^[2]
• Digoxin, marked baseline ST changes, left ventricular hypertrophy, bundle branch block, ventricular pacing and pre-excitation preclude reliable interpretation.
• Low risk premenopausal women have a higher false positive rate, so women unable to reach 5 METS may be better sent for perfusion imaging or pharmacologic stress.

Standard monitoring includes 12-lead ECG and blood pressure before, during and recovery. Blood pressure should rise by at least 10 mmHg during exercise; a sustained systolic drop of more than 10 mmHg, confirmed within 15 seconds, is a high-risk sign that often indicates severe left ventricular dysfunction or critical coronary disease and is an indication to stop ^[1]. A systolic drop of more than 20 mmHg is one of the high-risk criteria. Other early-termination indications are arrhythmia other than occasional ectopics, severe hypertension (systolic above 250 mmHg or diastolic above 120 mmHg), ST elevation or more than 2 mm excessive horizontal or downsloping depression, angina with dynamic ST change, poor perfusion and reaching 100 percent of predicted heart rate ^[1].

Post-test care is simple after exercise ECG: the patient rests until heart rate and ECG normalise, avoids driving if deconditioned, and receives the written result including functional capacity. Post-myocardial infarction testing should be limited to about 5 METS in the first week and a symptom-limited protocol delayed 4 to 6 weeks after uncomplicated infarction ^[1].

AHA/ACC guidelines rate exercise ECG as reasonable first-line testing for excluding ischaemia and estimating functional capacity in low-risk patients with an interpretable ECG, and as a reasonable test for intermediate to high-risk patients who can exceed 5 METS. In this modern framework, exercise ECG alone is not recommended for all, and ESC guidance prefers functional imaging where available, noting that exercise ECG is useful for functional capacity and arrhythmia assessment and as an alternative only when imaging is unavailable ^[3].

Stress echocardiography compares left ventricular wall motion and thickening at rest and under stress. Ischaemia in the territory of a flow-limiting stenosis makes the corresponding segments become hypokinetic, akinetic or dyskinetic during stress; the abnormality appears before the ECG changes in the classic ischaemic cascade ^[2]. Myocardial perfusion contrast imaging can be added, improving detection of ischaemia and detection of multivessel or balanced disease ^[2].

Stress echocardiography is most useful when the pretest likelihood of coronary disease is intermediate, commonly around 15 to 85 percent in European guidance, and is used for diagnosis, risk stratification, functional assessment of an intermediate lesion and post-revascularisation symptoms ^[2]. ^[3]

• Exercise is the preferred stress whenever possible because it measures true physiological load, provides prognostic data on exercise capacity and has a better safety profile; it also gives information that is unique to exercise, such as time-to-symptoms, blood pressure response and chronotropic response ^[2][3].
• Semi-supine bicycle exercise is the recommended approach in the BSE framework and is more sensitive than post-treadmill imaging ^[2].
• Treadmill imaging uses the standard Bruce protocol and is completed within 90 seconds of exercise termination, with imaging during exercise preferred where skill allows. ^[2]
• Dobutamine, a beta-1 agonist infused from 5 to 40 micrograms per kilogram per minute with atropine as required, is used when exercise is impossible or when viability and contractile reserve are the main question; it increases chronotropy and contractility rather than true vasodilatation ^[2][4].
• Vasodilators such as adenosine (140 micrograms per kilogram per minute), dipyridamole (0.56 mg per kilogram over four minutes, with a further 0.28 mg per kilogram over two minutes if needed) and regadenoson (400 micrograms bolus) create a flow gradient and are favoured for perfusion imaging and in patients with pacemakers ^[2].

A minimum of two trained operators is required, one for imaging and one for haemodynamic monitoring, ECG and drug administration, with at least one possessing advanced life support competency ^[2]. Images are acquired in apical four-chamber, two-chamber and three-chamber views and the parasternal short axis.

The target heart rate for stress echocardiography is calculated as 220 minus age, and imaging sensitivity is only maintained if performed above 85 percent of this value; failure to reach target but with normal images still carries higher events than a normal target-reaching study ^[2]. A reasonable absolute exercise level is more than 7 METS for men and 5 METS for women, and failure to reach these values predicts events even with a normal scan ^[2].

End points include ^[2]:

• Absolute: systolic blood pressure drop of more than 10 mmHg with symptoms, sustained or symptomatic ventricular tachycardia, ST elevation with symptoms (other than aVR or V1), central nervous symptoms, or a left ventricular thrombus.
• Relative: maximal effort at predicted heart rate, a new wall-motion abnormality, progressive ventricular dilatation or global dysfunction, an ST depression of more than 2 mm or axis shift, stress arrhythmia such as atrial fibrillation, supraventricular tachycardia or non-sustained ventricular tachycardia, severe hypertension above 230 mmHg, and inappropriate heart-rate fall.

Contraindications to exercise stress echocardiography include recent myocardial infarction (within two days), unstable angina not stabilised, uncontrolled arrhythmia causing symptoms or haemodynamic compromise, symptomatic severe aortic stenosis, uncontrolled heart failure, acute myocarditis or pericarditis and baseline hypertension above 200 over 110 mmHg ^[2]. Contraindications to dobutamine-atropine stress include previous hypersensitivity, recent infarction (within three days), ongoing unstable angina, acute heart failure, thrombus, recent significant ventricular arrhythmia, recurrent supraventricular arrhythmia, high-grade atrioventricular block, active endocarditis or myocarditis and severe arterial hypertension above 200 systolic or 110 diastolic mmHg; relative cautions include moderate aortic stenosis, resting outflow obstruction above 30 mmHg and an aortic aneurysm larger than 4 cm ^[2]. Vasodilator stress is contraindicated in reactive airway disease ^[4].

Complications are uncommon. Exercise stress echocardiography has a better safety profile than pharmacological stress, but pharmacologic protocols carry a definite risk of hypotension, arrhythmia or infarction, reported below 1 percent for dobutamine-atropine with correct training and left ventricular opacification ^[2].

Rate-slowing drugs are stopped 48 hours before the test in most patients to allow an adequate heart-rate response; the report should state if this was done ^[2]. Intravenous access is established for pharmacologic stress, or for contrast in exercise cases with suboptimal windows, defined as difficulty seeing two or more contiguous segments. A suboptimal window is a frequent reason to choose a different test entirely. Intravenous atropine is titrated in 300 microgram aliquots up to 1.2 mg; reversal with incremental metoprolol aliquots up to 5 mg is standard ^[2].

Coronary flow reserve can be measured during vasodilator stress using Doppler of the left anterior descending artery, with a cut-off of 2 indicating significant epicardial stenosis or ischaemia, and acceptable image quality in almost all patients with contrast ^[2].

Current framing from the testing comparison is that stress echocardiography offers sensitivity and specificity of roughly 80 to 89 percent for anatomically significant disease, with availability and low cost as strengths, and interpreter dependence as its main weakness ^[3].

Myocardial perfusion imaging (MPI) maps tracer uptake as a surrogate of regional myocardial blood flow, both at rest and under stress. Obstructive coronary disease produces a reduction of flow in the territory supplied by the narrowed artery that normalises at rest, and the stressor can be exercise or pharmacologic.

Single-photon emission computed tomography (SPECT) uses technetium-99m-labelled perfusion agents (sestamibi or tetrofosmin), usually after around 30 minutes (rest) or 60 minutes (stress) of delay, or thallium-201, which redistributes over time and allows viability assessment. ^[4]

Key technical and clinical points:

• Target heart rate is the same 85 percent of age-predicted maximum (220 minus age) ^[4].
• Vasodilator stress is preferred in patients unable to exercise or in those with left bundle branch block or paced rhythm; it is contraindicated in significant reactive airway disease ^[4].
• Dobutamine is a reserve agent, with 2 to 3 fold increases in flow and slightly lower diagnostic yield, and usual contraindications apply ^[4].
• Methylxanthines, caffeine and theophylline, competitively block adenosine receptors, so caffeine-containing foods and drinks must be avoided for at least 12 to 24 hours before vasodilator stress ^[4].
• Thallium is avidly extracted with an efficiency of around 85 percent, and technetium agents are extracted with an efficiency of around 65 percent ^[4].
• Normal or low-risk scan: a patient is at less than 1 percent risk of cardiac death or nonfatal infarction over about one year after a completely normal scan, and a high-risk scan shows large reversible perfusion defects, low ejection fraction below 40 percent, end-systolic or end-diastolic dilatation, or increased lung uptake ^[4].
• Defects are graded by size and severity during interpretation, with perfusion reported by segment.

Radiation exposure is around 12 to 14 millisieverts for a full SPECT study ^[3]. Different protocols exist (one day, two day, dual isotope), and drug and camera combinations affect dose and image quality; there is no clearly established superiority of one protocol ^[4]. Motion and breast or diaphragmatic attenuation are common sources of error, so cine raw images, ECG gating, attenuation correction and prone imaging are part of careful interpretation ^[4].

Positron emission tomography (PET) uses rubidium-82, nitrogen-13 ammonia or oxygen-15 water, with higher resolution and lower radiation exposure of about 3 to 4 millisieverts ^[3]. PET is accurate, can measure absolute myocardial blood flow and assess the transmural depth of reduced perfusion, and is often preferred in obese patients and when the ECG shows left bundle branch block. Its main limitations are cost, availability and radiotracer supply; PET allows pharmacologic stress only, not exercise ^[3]. When a perfusion study is normal, prognosis is excellent and the patient can often be reclassified to a lower-risk category.

SPECT and PET are first-line functional tests in higher-risk ambulatory patients according to AHA/ACC, while ESC recommends noninvasive functional imaging, including these modalities, as the initial test for patients whose symptoms suggest ischaemia and whose likelihood is between 15 and 85 percent ^[3].

Coronary computed tomography answers an anatomic question: how much atherosclerosis is present and does it obstruct the lumen?

Coronary artery calcium (CAC) scoring is a non-contrast ECG-gated CT that takes roughly 10 to 15 minutes and about 1 millisievert of radiation ^[3]. The result is the Agatston score, which is an expression of calcium volume and density. It is excellent for risk stratification: a score of zero has a sensitivity of about 98 percent but specificity of 40 percent, and in contemporary cohorts only 1.8 percent and 1 percent of patients with a score of zero had obstructive disease on coronary CT and invasive angiography respectively, corresponding to a high negative predictive value ^[3]. It is used best in older low or intermediate-risk patients; in patients under 45 years non-calcified plaque means CAC of zero does not reliably exclude disease ^[3].

Coronary CT angiography (CCTA) is a contrast-enhanced ECG-gated study, with around 1 millisievert of radiation, excellent sensitivity for stenosis (around 93 to 99 percent in modern reviews) and moderate specificity (63 to 86 percent) ^[3]. It also identifies nonobstructive plaque, which has become important because atherosclerosis alone, not purely obstructive disease, drives events and should be treated ^[3]. Limitations reflect the physics:

• Heavy calcification causes artefact and overestimates stenosis.
• Arrhythmia and a high heart rate blur the images.
• Metallic stents produce artefact.
• Technical dependence on beta blockade and, sometimes, nitrates to slow the heart may itself be a limitation.

CCTA is contraindicated with contrast intolerance, chronic kidney disease, pregnancy, tachyarrhythmia, and when the patient cannot receive medications required for image acquisition ^[3]. ESC guidance prefers CCTA, when available, to rule out obstructive coronary disease in symptomatic patients whose likelihood is not polarised by clinical assessment alone, while AHA/ACC rates CCTA class 1 for intermediate-high-risk patients with stable chest pain ^[3][8].

Fractional flow reserve derived from CT (CT FFR) uses computational fluid dynamics to provide noninvasive pressure ratios distal to lesions, with sensitivity 85 to 90 percent and specificity 82 to 86 percent in most comparisons, and improving decisions after an intermediate stenosis of 40 to 90 percent ^[3]. Stress CT perfusion is a developing technique. CT with FFR and stress perfusion adds physiological information without a second modality, but adds complexity and assessment time.

Cardiac MRI gives high spatial and temporal resolution without ionising radiation; MRI uses magnetic field gradients rather than x-rays. A stress perfusion protocol uses vasodilator stress (adenosine, dipyridamole or regadenoson) and a gadolinium-based contrast to detect regional perfusion defects. MRI is also the reference technique for right and left ventricular volumes, function and tissue characterisation, using late gadolinium enhancement for scar and extracellular expansion.

CMR strengths in this clinical area ^[5]:

• It is accurate, on a par with other stress imaging modalities for stable and acute chest pain.
• It quantifies myocardial blood flow reserve, an additional class 2a indication in the AHA/ACC framework for PET and CMR when quantification is available. ^[5]
• It has become the test of choice for detecting non-ischaemic causes of chest pain and troponin elevation, such as myocarditis and MINOCA.
• It delivers no ionising radiation to the breast, making it particularly suitable for younger women when local expertise is available. ^[5]
• It can solve the puzzle of unexplained ischaemia in patients with nonobstructive coronary arteries.

CMR limitations include availability, cost, artefact from some implants, claustrophobia (patients with severe claustrophobia may require sedation or a different test), and the need for gadolinium contrast with the usual caution in pregnancy or severe renal dysfunction ^[3]. Older implantable devices are a relative contraindication; modern devices are increasingly MRI-conditional but local protocol must be followed.

The 2021 AHA/ACC guideline assigns 15 indications to CMR, ranging from intermediate-risk assessment to myocarditis and MINOCA ^[5]. CMR has gained ground rapidly because it provides both anatomy at a tissue level and functional ischaemia in a single exam.

The 2024 ESC guidance structures the work into four steps: clinical evaluation and basic tests; a further cardiac examination with resting echocardiography and estimation of likelihood; diagnostic testing; then lifestyle, risk-factor and medical management ^[8].

Pretest likelihood separates the branches. With very low likelihood (5 percent or lower), further testing is unnecessary or can be deferred. With very high likelihood, invasive coronary angiography is often chosen directly. For intermediate to high likelihood, noninvasive functional or anatomic imaging is indicated ^[3]. ^[8]

AHA/ACC uses a slightly different language but a similar pathway: a bedside TTE and basic testing, then risk stratification; in low-risk patients (roughly 15 percent or lower) CAC score or exercise ECG may be used, whereas in intermediate-high-risk patients stress echocardiography, MPI, SPECT, PET, CMR and/or CCTA are all class 1 effective tests for diagnosing myocardial ischaemia and estimating MACE risk ^[3]. ^[5]

The 2024 ESC framework is more explicitly algorithmic: CCTA is preferred to rule out obstructive disease and detect nonobstructive disease; functional imaging is preferred to correlate symptoms with ischaemia, assess viability and guide revascularisation; PET is preferred for absolute myocardial blood flow, with CMR perfusion as an alternative ^[8]. ESC also recommends invasive angiography when the likelihood is very high, severe symptoms persist despite therapy, or event risk is high ^[8].

Several points make the choice easier in day-to-day practice:

• If the question is "does this patient have obstructive coronary disease?", CCTA is the most straightforward initial test in patients over about 40 or 45 years, as long as rhythm, kidneys and contrast tolerance are acceptable.
• If the question is "is this chest pain ischaemic, and how bad is prognosis?", stress echo, SPECT, PET or CMR gives the ischaemia signal and usually the left ventricular function at the same time.
• If both anatomy and function may be needed, sequential testing can be rational: abnormal CCTA can be followed by functional testing, or an abnormal functional test by coronary CT or invasive angiography ^[3].
• Individual characteristics steer the choice. Chronic lung disease and morbid obesity favour PET or CMR over SPECT; younger women favour radiation-free CMR; renal dysfunction pushes away from both contrast CT and gadolinium; metallic implants may push away from CMR; severe aortic stenosis or marked hypertension makes exercise and dobutamine stress unsafe.
• Low-resource settings: centres may have TTE, exercise ECG and basic SPECT but not PET, CCTA or CMR. In such settings TTE plus exercise ECG is a safe first combination; SPECT or stress echo should be used when available to avoid unnecessary invasive procedures; any abnormality that needs characterisation is an indication for referral; and locally available CT scanners (non-gated calcium score) can still refine risk stratification. Good prognostic data can come from simple exercise capacity alone.
• Do not over-test: the stress ECG is nondiagnostic, not negative, if target heart rate is not reached; a negative test after adequate stress is genuinely reassuring in low to intermediate-risk patients.

Whatever the test, safety and documentation are generic: ECG and blood-pressure monitoring, attention to hydration after contrast or radiopharmaceutical, avoidance of caffeine for 24 hours after vasodilator stress in delayed recovery, a period of observation, and an explicit plan in the report. Stress laboratories must have resuscitation equipment and trained staff.

The report should also contain the clinical question, indication, protocol, stress adequacy, result, possible artefacts, conclusion and the implied risk category. Stress echo reports should include ECG findings, reason for termination, symptoms and image quality ^[4].

The complications that follow these tests include, but are not limited to:

• Exercise testing: rare infarction or death (up to 1 per 2500), arrhythmia, hypotension.
• Dobutamine-atropine stress: hypotension, vagal slowing and arrhythmia, generally reported below 1 percent with trained supervision; stop with metoprolol.
• SPECT/PET: vasodilator-induced chest pain, headache and bronchospasm (adenosine is contraindicated in reactive airway disease); radiation dose at roughly 3 to 4 mSv for PET and 12 to 14 mSv for SPECT.
• Coronary CT: contrast reactions, allergic phenomena, nephrotoxicity risk, beta blocker induced bradycardia, and radiation around 1 mSv.
• Cardiac MRI: claustrophobia, gadolinium allergy and the rare risk of nephrogenic systemic fibrosis in severe renal dysfunction.
• Transoesophageal echocardiography: oesophageal perforation or bleeding, rare but serious.

Escalation to invasive coronary angiography is made when the risk suggested by the noninvasive test is high, when symptoms persist despite optimal therapy, or after equivocal tests, with functional assessment of any intermediate lesion reported at angiography ^[8].

• Echocardiography measures cardiac structure and function; functional tests (exercise ECG, stress echo, MPI) detect ischaemia and prognosis; CT and MRI characterise anatomy and tissue.
• Transthoracic echocardiography is safe, fast and usually the first imaging test; it does not exclude coronary disease.
• Exercise ECG uses 85 percent of 220 minus age as the standard endpoint; 10 METS or more predicts an excellent prognosis; a nondiagnostic test is not a negative test.
• Stress echocardiography works through new regional wall motion abnormality under stress; it prefers exercise but uses dobutamine, adenosine, dipyridamole or regadenoson when exercise is impossible.
• SPECT offers robust prognostic information and a 12 to 14 mSv radiation load; normal results imply a very low annual event rate.
• PET is accurate and can quantify myocardial blood flow, at a lower 3 to 4 mSv radiation load, but has higher cost and lower availability.
• Coronary CT has excellent negative predictive value and identifies nonobstructive plaque, but is limited by arrhythmia, calcification and contrast tolerance.
• Cardiac MRI has no ionising radiation, quantifies blood flow reserve and tissue, and is particularly attractive in younger women and in myocarditis or MINOCA.
• First-line test selection: CAC score or exercise ECG in low risk, CCTA in many intermediate risk patients, and stress imaging in those with intermediate-high risk or when functional ischaemia is the question.
• Guidelines continue to differ: ESC 2024, AHA/ACC 2021 chest pain guidance and NICE can place different emphases on CCTA versus functional imaging, so local practice may vary.

None are formally linked below; related topics may be added once their MedGrasp slugs are confirmed. Relevant adjacent topics include cardiac physical examination and interpretation of the ECG, heart failure, chronic coronary syndrome, valvular heart disease and perioperative cardiac assessment. Plain text links only.