Why ECG and Echocardiography Are Ordered When Rheumatic Fever Is Suspected

The pediatrician had already examined the swollen knee twice. Then she asked a question the parents did not expect: had anyone in the house had a sore throat a month ago? A vague memory surfaced, a few days off school, a scratchy voice, nothing that seemed worth mentioning. Within the hour the child was lying on a bed with ten sticky pads on his chest, and an appointment for a heart ultrasound had been booked for the next morning.

That sequence, joint pain, a question about strep, then rheumatic fever echocardiogram and ECG tests, can feel like a leap. A sore knee and a heart scan do not seem to belong in the same conversation.

They do, and the reason is one of the most important ideas in this whole story: rheumatic fever is an immune reaction that can quietly involve the heart valves, and the only reliable way to know is to look and to listen with the right instruments.

What are rheumatic fever echocardiogram and ECG tests actually looking for?

Rheumatic fever is an inflammatory illness that can follow an untreated or incompletely treated group A streptococcal throat infection. The immune system, primed to fight the bacterium, mistakenly reacts against the body’s own tissues, most importantly the joints, the skin, the brain and the heart. When the heart is involved, clinicians call it carditis, which simply means inflammation of heart tissue.

Two tests do most of the work of finding that inflammation. An electrocardiogram, or ECG, records the heart’s electrical activity through electrodes placed on the skin. An echocardiogram, often shortened to echo, is an ultrasound scan that shows the heart’s chambers and valves moving in real time.

The two answer different questions. The ECG asks whether the electrical signal is traveling through the heart at a normal speed and in a normal rhythm. Inflammation near the heart’s wiring can slow the signal between the upper and lower chambers, a change that is measurable even when the child feels fine. The echo asks whether the valves, the one-way doors between chambers, are opening and closing properly, or whether inflammation has made them leak.

Neither test diagnoses rheumatic fever by itself. Both feed into a structured framework, described later, that combines heart findings with joint symptoms, skin signs, blood tests and proof of a recent strep infection. The point of ordering them early is that heart involvement can be silent. According to the Mayo Clinic, damage to heart valves may not be noticed until years after the illness, when it has already become rheumatic heart disease. Looking early gives the care team a baseline and a chance to plan protection.

How does a sore throat turn into a heart problem weeks later?

The chain of events starts with a bacterium called group A Streptococcus, the cause of strep throat and scarlet fever. In most people the infection clears, with or without antibiotics, and that is the end of it. In a small minority, the immune system’s response to the bacterium goes awry.

The leading explanation is molecular mimicry. Certain proteins on the surface of the bacterium resemble proteins found in human tissue, including heart valve and heart muscle tissue. Antibodies and immune cells produced to attack the bacterium recognize these look-alike structures and attack them too. The result is inflammation in places the infection never reached.

Timing matters for anyone trying to make sense of a diagnosis. The CDC notes that rheumatic fever usually develops one to five weeks after a strep throat or scarlet fever infection. By then the sore throat has often been forgotten, which is why doctors ask about it directly and why parents are sometimes puzzled by the question.

The immune reaction is not random in whom it strikes. The Mayo Clinic describes rheumatic fever as most common in children between about 5 and 15 years old, although younger children and adults can be affected. The NHS adds that it has become rare in high-income countries, largely because strep infections are recognized and treated, but it remains common in many parts of the world where access to care is limited.

Why do the heart valves take the brunt? The mitral valve, between the left atrium and left ventricle, is under high pressure with every beat, and its tissue appears especially vulnerable to the cross-reacting immune attack. That is exactly why the echo focuses so closely on it.

What are the first signs of rheumatic fever that prompt testing?

The features that raise a clinician’s suspicion are best understood as a pattern rather than a list to tick off at home. The Mayo Clinic and CDC describe the illness as typically beginning with fever and painful, swollen joints, most often the knees, ankles, elbows and wrists. A distinctive habit of rheumatic joint pain is that it migrates: one joint improves while another flares.

Heart involvement may announce itself with chest discomfort, breathlessness, a racing heartbeat or unusual tiredness, or it may produce no symptoms at all and be detected only as a new murmur when the doctor listens with a stethoscope. That silent possibility is the single biggest reason imaging is ordered rather than waited on.

Less common features round out the picture. Sydenham chorea is the medical name for jerky, involuntary movements of the hands, feet or face, sometimes accompanied by emotional outbursts, and it can appear months after the original infection. Erythema marginatum is a flat or slightly raised, painless rash with a pink border that comes and goes. Subcutaneous nodules are small, firm, painless lumps under the skin, usually over bony points.

None of these signs is unique to rheumatic fever. Migrating joint pain occurs in other conditions, and fever with sore joints is common in ordinary viral illnesses. What tips the balance is the combination, plus laboratory proof that a strep infection happened recently. A child with a swollen knee, a low-grade fever and a throat swab or antibody test pointing to recent strep is a very different case from a child with a swollen knee alone, and it is that first combination that sends the team toward the ECG machine and the ultrasound room.

Where do the Jones criteria for rheumatic fever fit in?

Because no single blood test confirms rheumatic fever, clinicians rely on the Jones criteria, a diagnostic framework maintained by the American Heart Association and used internationally. The criteria divide findings into major and minor groups, and a diagnosis generally requires evidence of a preceding strep infection plus either two major findings or one major and two minor findings.

The major criteria are carditis, arthritis affecting several joints, chorea, erythema marginatum and subcutaneous nodules. The minor criteria include fever, joint pain without swelling, raised inflammatory markers in the blood (ESR and CRP, which are measures of how active inflammation is) and a prolonged PR interval on the ECG.

Two things in that list explain the tests directly. The ECG finding of a prolonged PR interval is itself a minor criterion; the machine can contribute a piece of the diagnostic puzzle. And carditis is a major criterion, which in the current version of the criteria can be established either clinically, by a new murmur, or by echocardiography alone, a category known as subclinical carditis.

That second point was a significant shift. Under older versions, a valve leak seen only on ultrasound did not count. The revised criteria recognize that Doppler echocardiography, a technique that measures the speed and direction of blood flow, can detect pathological regurgitation the stethoscope misses. The American Heart Association now recommends echocardiography with Doppler in all cases of confirmed or suspected acute rheumatic fever.

The criteria also adjust the thresholds for fever and joint findings depending on whether the person comes from a population where rheumatic fever is rare or common, an acknowledgment that the disease behaves differently in different settings. Your care team applies the version appropriate to your situation.

What actually happens during the ECG?

The ECG is the simpler of the two tests, and for many children the most reassuring part is learning that nothing goes into the body. The NHS describes it as a quick, painless test that usually takes about five minutes. A nurse or technician attaches small adhesive electrodes to the chest, arms and legs, typically ten in total. Wires connect these pads to a machine that records the heart’s electrical impulses as a trace on paper or screen.

Lying still is the main job. Movement, shivering or talking can add electrical noise to the trace, so the room is kept warm and the child is asked to relax for a few seconds while the recording is captured. Sometimes a technician gently wipes the skin first so the pads stick; on a hairy chest, a small area may be shaved. The pads are peeled off at the end, occasionally leaving a faint red mark that fades within hours.

Preparation is minimal. There is no fasting, no sedation and no radiation. Parents can usually stay in the room, and a small child may sit on a lap for part of the setup. Bringing a familiar toy or a screen with a quiet video can make the two minutes of stillness easier.

The recording itself is interpreted by a clinician, who measures the intervals between the waves of each heartbeat. In rheumatic fever, the interval of interest is the PR interval, the time it takes for the electrical impulse to travel from the upper chambers to the lower ones. The next section explains what a change in that interval means. For the family, the practical message is simple: the ECG is brief, safe, and often repeated on later visits to track recovery.

What can the ECG show in rheumatic fever?

The heart’s electrical system works like a relay. An impulse begins in the sinus node in the right atrium, spreads across the upper chambers, pauses briefly at the atrioventricular node, then travels down into the ventricles. The PR interval on the ECG measures that journey from the start of atrial activation to the start of ventricular activation.

Inflammation in and around the atrioventricular node can slow the relay. On the trace, that shows as a PR interval longer than expected for the child’s age and heart rate, a pattern called first-degree heart block. The term sounds alarming, but first-degree block means every impulse still gets through; it simply takes longer. In the Jones criteria this finding is a minor criterion, useful for building the diagnosis and usually reversible as the inflammation settles.

Less often, the ECG reveals more significant conduction delay, where some impulses are dropped, or rhythm disturbances. These are uncommon in rheumatic fever but are precisely the findings a team wants to know about early, because they change how closely the heart is monitored.

The ECG can also hint at pericarditis, inflammation of the sac around the heart, through characteristic changes in the shape of the trace, and it can reflect a fast heart rate out of proportion to fever, another soft clue to heart involvement.

What the ECG cannot do is show the valves. A completely normal ECG does not rule out carditis, because valve leakage does not necessarily disturb the electrical system. This limitation is the main reason the two tests are ordered together rather than one replacing the other. Think of the ECG as checking the wiring and the echo as checking the plumbing.

What happens during the echocardiogram?

An echocardiogram is an ultrasound scan of the heart. The Mayo Clinic describes a standard transthoracic echo, the type used in suspected rheumatic fever, as a test that usually takes less than an hour and involves no radiation. The person lies on a bed, usually on the left side, with the chest uncovered. A sonographer applies cool gel and presses a handheld probe, called a transducer, against several spots on the chest and upper abdomen.

The probe sends high-frequency sound waves into the body and picks up the echoes bouncing back from heart structures. A computer turns those echoes into moving images. Firm pressure is sometimes needed to get a clear view between the ribs, which can feel uncomfortable but should not hurt. The room is dim so the screen is easier to read, and the machine makes whooshing sounds when Doppler is switched on to measure blood flow.

Children often find the experience easier than expected once they realize it resembles the scans used in pregnancy. Being asked to hold a breath for a few seconds, or to roll slightly, is normal. Small children may be scanned while a parent holds them; sedation is rarely needed for this type of echo, and any decision about it rests with the care team.

There is no fasting for a transthoracic echo, no needles and no recovery period. The gel wipes off, and normal activity can resume immediately. Results are interpreted by a cardiologist, a heart specialist, who reviews the images and Doppler measurements after the scan. Families sometimes receive a preliminary comment on the day, but the formal report and its meaning for the diagnosis usually come at a follow-up conversation with the treating team.

What does the echo reveal about the valves?

The sonographer’s attention in suspected rheumatic fever goes first to the mitral valve, then to the aortic valve. Both sit on the left side of the heart, where pressures are highest, and both are the valves most often affected by rheumatic inflammation.

Inflamed valve leaflets swell and may not meet cleanly when the valve closes. Blood then slips backward through the gap, a leak called regurgitation. Doppler imaging shows this as a jet of color flowing the wrong way. The cardiologist measures how long the jet lasts, how far it reaches and how fast it moves; the Jones criteria set specific thresholds for calling a leak pathological rather than the trivial backflow that many healthy hearts show.

Beyond the flow itself, the images can reveal structural changes: thickened leaflets, a small mobile nodule on a leaflet edge, or chords that tether the leaflets appearing stretched or lengthened. The echo also measures chamber sizes and how vigorously the left ventricle pumps, because significant regurgitation over time makes the ventricle work harder and enlarge.

Pericardial fluid, a small collection around the heart, may be visible if the outer sac is inflamed. Narrowing of a valve, called stenosis, is not a feature of the acute illness; it develops over years of scarring in people who go on to have rheumatic heart disease, which is one reason the acute-phase echo serves as such an important baseline for future comparison.

An echo that shows no pathological regurgitation is reassuring but not final. The World Health Organization notes that repeated episodes of rheumatic fever are what drive progressive valve damage, so a normal first scan is the beginning of surveillance rather than a discharge from it.

ECG versus echocardiogram in suspected rheumatic fever: a side-by-side view

Families often ask why both tests are needed when one already sounds thorough. The table below sets out how they differ and why each has a distinct place in the diagnostic framework.

Feature	ECG	Echocardiogram
What it examines	Electrical timing and rhythm	Valve structure, blood flow, chamber size and pumping
Key rheumatic finding	Prolonged PR interval (first-degree heart block)	Pathological mitral or aortic regurgitation; leaflet thickening
Role in Jones criteria	Minor criterion	Can establish carditis, a major criterion, even without a murmur
Typical duration	About 5 minutes (NHS)	Usually less than an hour (Mayo Clinic)
Radiation or needles	None	None
Main limitation	Cannot see valves; normal trace does not exclude carditis	Cannot measure conduction delay; image quality varies with body habitus
How often repeated	Often at follow-up to confirm the interval has normalized	At intervals set by the team to track valve changes

Read together, the two tests cover the heart’s two systems that rheumatic inflammation can disturb. A prolonged PR interval with a clean echo suggests conduction involvement without valve injury; a normal ECG with mitral regurgitation on Doppler points to subclinical carditis. Either result, combined with joint, skin or laboratory findings and evidence of recent strep, helps the team decide whether the criteria are met.

Blood tests complete the workup. A throat swab or rapid antigen test looks for current strep, while antibody tests such as anti-streptolysin O and anti-DNase B, which rise after a strep infection and stay elevated for weeks, provide the proof of a preceding infection the criteria require. Inflammatory markers help gauge how active the illness is and are rechecked as it settles.

Who is tested straight away, and who is asked to wait or repeat?

The short answer is that anyone in whom rheumatic fever is a genuine possibility should have both tests, and the American Heart Association’s recommendation that echocardiography be performed in all suspected cases reflects that. The nuance lies in timing, urgency and repetition.

Tested promptly, often the same day, are children and young people with the classic combination: migrating joint pain or swelling, fever, and either a recent documented strep infection or a story strongly suggesting one. A new murmur heard on examination, breathlessness, chest pain or an unusually fast heart rate moves the echo from routine to urgent, because these features suggest the heart may already be involved.

Chorea deserves its own mention. Because the movement disorder can appear months after the original infection, by which time joint symptoms and blood markers may have faded, the Jones criteria allow chorea alone to support a diagnosis. These children are still sent for an ECG and echo, since heart involvement can accompany chorea silently.

Who waits? Sometimes the first echo is technically difficult, or shows borderline regurgitation that does not clearly meet the thresholds for a pathological leak. In that situation the team may ask for the scan to be repeated after a few weeks rather than labeling the child immediately. Children with joint pain but no evidence of a recent strep infection, and no other features, may be observed and re-examined instead, because the criteria cannot be met without that evidence.

Adults are evaluated the same way, although the illness is less common and joint symptoms tend to dominate. In every case the decision about when to scan and when to rescan belongs to the treating team, who weigh the whole picture rather than any single finding.

What do the following days and weeks usually look like?

Once the tests are done, the immediate focus is on confirming or excluding the diagnosis and on making sure any lingering strep is cleared. If rheumatic fever is confirmed, the CDC and Mayo Clinic describe treatment as having three broad aims: eliminate the bacterium with antibiotics, ease inflammation and joint pain with anti-inflammatory medicines, and protect the heart, which may include rest during the acute phase and closer monitoring when carditis is present. Specific medicines and how they are used are decisions for the prescribing clinician.

Joint symptoms in rheumatic fever typically respond quickly once anti-inflammatory treatment begins, and the arthritis does not cause lasting joint damage, a point the Mayo Clinic makes to reassure families. Fever usually settles within days as well. Inflammatory blood markers fall more slowly and are often rechecked to confirm the illness is quietening.

The heart takes longer to declare itself. A prolonged PR interval on the ECG often returns to normal as inflammation resolves, and repeating the ECG is a simple way to document that. Valve regurgitation seen on the first echo may improve, remain stable or occasionally progress, so a follow-up echo is usually scheduled at an interval chosen by the cardiologist. According to the Mayo Clinic, the inflammation of the acute illness may last several weeks to several months.

Chorea, when present, follows its own timetable and can persist for months before fading. Children may need schooling adjustments during that period.

The other big change in these weeks is the start of long-term protection against further strep infections, discussed in the next section. Families often describe this as the moment the diagnosis becomes real: the acute illness passes, but the follow-up calendar stays.

Why the heart findings matter for years, not just weeks

The reason clinicians invest so much in getting the heart assessment right is that rheumatic fever is rarely a one-off risk. Each new group A strep infection can trigger a recurrence, and the WHO explains that repeated episodes are what progressively scar the valves, leading to rheumatic heart disease. Globally the WHO estimates that rheumatic heart disease affects around 40 million people and causes roughly 300,000 deaths each year, most in low- and middle-income settings.

Preventing recurrences is therefore the cornerstone of long-term care. This is done with secondary prophylaxis: regular, ongoing antibiotics from the penicillin class, given for years to stop new strep infections before they can provoke the immune system again. The Mayo Clinic describes this preventive treatment as continuing for many years, and for some people into adulthood or for life, depending on whether the heart was involved and how severely.

That is where the echo result becomes a long-term decision tool. Guidelines set the recommended duration of prophylaxis according to the presence of carditis and whether residual valve disease remains. A child whose echo was normal throughout is treated differently from one with persistent mitral regurgitation, and the periodic follow-up echo is how the team decides which category applies as time passes.

Long-term surveillance also watches for the slow consequences of valve damage: enlargement of heart chambers, reduced pumping, rhythm disturbances, or narrowing of a scarred valve years later. These are the problems that may eventually require valve intervention, and catching them early on ultrasound offers the widest range of options.

Dental and general health matter too. People with established rheumatic valve disease are advised to maintain good oral hygiene and to tell dentists and other clinicians about their history, so any decisions about protecting the valves during procedures can be made by the team.

What people often get wrong about rheumatic fever and these tests

“The ECG was normal, so the heart is fine.” A normal ECG rules out conduction delay at that moment, nothing more. Valve leakage does not show on an ECG, which is why the echo is needed as well.

“The echo will hurt or involve radiation.” An echocardiogram is ultrasound, the same technology used during pregnancy. It involves no radiation and no needles. Firm probe pressure may be briefly uncomfortable, but it is not painful.

“Is 99.5 a fever?” Not by the usual medical definition. The Mayo Clinic describes a fever as a temperature of 100.4°F (38°C) or higher. A reading of 99.5°F sits within the normal range for many people, particularly late in the day or after activity. In the Jones criteria, fever counts as a minor criterion only above defined thresholds, so a slightly raised reading does not carry the weight people sometimes assume.

“A toddler can’t have a fever without other symptoms.” Toddlers frequently run a fever with no obvious source, often from a viral infection. Fever alone is not rheumatic fever, which requires joint, heart, skin or movement findings plus evidence of recent strep. A persistent unexplained fever in a young child should still be assessed by a clinician.

“We would remember a strep infection.” Often families do not. Strep throat can be mild, and the CDC notes the gap before rheumatic fever is one to five weeks, long enough for a minor sore throat to be forgotten. This is why antibody blood tests, not memory, provide the evidence.

“One normal echo means no more heart checks.” A normal baseline is good news, but recurrences are the real threat. Follow-up scans and prophylaxis remain part of the plan for as long as the team advises.

Questions to ask your care team about rheumatic fever diagnosis tests

A diagnosis built from criteria rather than a single test can feel abstract. Asking precise questions helps turn the framework into something a family can follow. Consider bringing these to the next appointment, and write down the answers.

• Which Jones criteria has my child met so far, and which are still uncertain?
• Did the ECG show a prolonged PR interval or any other change, and when will it be repeated?
• Did the echo show any valve regurgitation? If so, which valve, and does it meet the threshold for pathological leakage?
• Is this being classified as clinical carditis, subclinical carditis or no carditis, and what does that mean for follow-up?
• How was the recent strep infection confirmed: throat swab, rapid test or antibody levels?
• When is the next echocardiogram planned, and what changes would prompt an earlier scan?
• What restrictions on physical activity or sport apply during the acute phase, and when will they be reviewed?
• How long is secondary prophylaxis expected to continue in our case, and what factors could change that?
• Who should we contact between visits if new symptoms appear, and which symptoms count as urgent?
• Should siblings or other household members be checked for strep?
• What should our dentist know about this diagnosis?
• If chorea is part of the picture, what support is available for school?

It is reasonable to ask for a copy of the echo report and to have unfamiliar terms explained in plain language. Regurgitation, subclinical carditis and PR interval are ordinary vocabulary to a cardiologist but not to most families, and a good team expects to translate.

Finally, ask how the team will weigh a borderline result. Knowing in advance that a repeat scan may be requested, and why, removes much of the anxiety if that call comes.

When to call your doctor

Rheumatic fever is a diagnosis made and managed by a clinical team, and the tests described here are the beginning of a relationship rather than a single event. Certain developments, though, should not wait for the next scheduled appointment.

Seek urgent medical attention, or call emergency services, for chest pain, difficulty breathing or breathlessness at rest, fainting or near-fainting, a very fast or irregular heartbeat, or new swelling of the legs and abdomen. These can indicate that heart involvement is progressing or that the heart is struggling to keep up, and they need prompt assessment.

Contact the care team the same day for a new or worsening sore throat, since a fresh strep infection carries the risk of triggering a recurrence; for fever returning after the acute illness had settled; for joint pain or swelling coming back; for new involuntary movements, clumsiness or unexplained changes in mood or handwriting that could signal chorea; or for a new rash that comes and goes.

Let the team know if a dose of preventive antibiotic is missed or if an injection or prescription cannot be obtained as planned, so they can advise. Do not stop or change any medicine without speaking to the prescribing clinician.

For parents of young children, a persistent fever without an obvious cause, unusual drowsiness, refusal to drink, or a child who seems distressed in a way that feels different from previous illnesses always warrants a call, regardless of whether rheumatic fever is suspected. The Mayo Clinic and NHS both advise that any child with a sore throat accompanied by fever, difficulty swallowing or swollen tender glands should be assessed, because treating strep promptly is the most effective way to prevent rheumatic fever in the first place.

Frequently asked questions

What are the first signs of rheumatic fever?

The illness most often begins with fever and painful, swollen joints that shift from one joint to another, typically the knees, ankles, elbows or wrists, one to five weeks after a strep throat infection. Some people develop chest discomfort, breathlessness or unusual tiredness from heart inflammation, while others have no heart symptoms at all. Less common early features include a faint migrating rash, small painless lumps under the skin, and jerky involuntary movements. A clinician should assess this pattern.

Which finding is consistent with rheumatic fever on the ECG or echo?

On the ECG, a prolonged PR interval, meaning the electrical impulse takes longer than normal to pass from the upper to the lower heart chambers, is the classic finding and a minor Jones criterion. On the echocardiogram, pathological regurgitation of the mitral or aortic valve, with or without thickened leaflets, is consistent with rheumatic carditis and counts as a major criterion. Neither finding alone confirms the diagnosis; each is weighed with other clinical and laboratory evidence.

Is 99.5 a fever?

No, by the usual medical definition. The Mayo Clinic defines a fever as a body temperature of 100.4°F (38°C) or higher. A reading of 99.5°F falls within normal daily variation for many people, especially in the late afternoon or after exercise. In the context of rheumatic fever, the Jones criteria count fever as a minor criterion only above set thresholds, so a mildly raised temperature carries little diagnostic weight on its own.

Can a toddler have a fever without any other symptoms?

Yes, and it is common. Young children frequently develop a fever with no obvious source, often from a viral infection that resolves on its own. Fever alone does not indicate rheumatic fever, which requires additional features such as joint swelling, heart involvement, rash or abnormal movements together with evidence of a recent strep infection. A toddler with a fever lasting more than a few days, or who seems unusually unwell, drowsy or unwilling to drink, should be seen by a clinician.

Does a normal ECG rule out heart involvement in rheumatic fever?

No. The ECG measures the heart’s electrical timing and rhythm, so it can detect the conduction delay that inflammation sometimes causes, but it cannot show the valves. Rheumatic carditis most often affects the mitral valve, causing a leak that is invisible on an ECG and detectable only by echocardiography with Doppler. This is why the American Heart Association recommends an echo in all suspected cases, regardless of what the ECG shows.

How long does an echocardiogram take for a child, and does it hurt?

A standard transthoracic echocardiogram usually takes less than an hour according to the Mayo Clinic, and it does not hurt. The sonographer applies gel and presses an ultrasound probe against the chest, which can feel firm or cool but is not painful. There is no radiation, no injection and no fasting. Most children manage the scan awake, often while a parent stays close, and normal activity can resume immediately afterward.

What are the Jones criteria for rheumatic fever?

The Jones criteria are the diagnostic framework used to identify rheumatic fever in the absence of a single confirmatory test. Major criteria are carditis, arthritis in several joints, chorea, erythema marginatum and subcutaneous nodules. Minor criteria include fever, joint pain, raised inflammatory blood markers and a prolonged PR interval on ECG. A diagnosis generally requires evidence of a recent strep infection plus two major criteria, or one major and two minor. The thresholds vary by population risk.

What are the heart symptoms of rheumatic fever to watch for?

Heart involvement may cause chest pain or discomfort, shortness of breath, a fast or pounding heartbeat, unusual fatigue, or, in more significant cases, swelling of the legs. Many people with carditis, however, have no symptoms at all, and the only clue is a new murmur or an abnormal echo. Chest pain, breathlessness at rest, fainting or an irregular heartbeat should prompt urgent medical assessment rather than waiting for a scheduled appointment.

Why do I need blood tests as well as the ECG and echo?

Because the Jones criteria require proof that a group A strep infection occurred recently, and neither heart test can provide that. A throat swab or rapid antigen test looks for current infection, while antibody tests such as anti-streptolysin O and anti-DNase B detect the immune response to a recent one. Inflammatory markers such as ESR and CRP help gauge how active the illness is and are rechecked as it settles to confirm improvement.

Will the heart tests need to be repeated after rheumatic fever?

Usually, yes. A prolonged PR interval often normalizes as inflammation resolves, and a repeat ECG documents that. Valve findings on the echo may improve, stay stable or occasionally progress, so cardiologists typically schedule follow-up scans at intervals based on the initial result. The WHO emphasizes that repeated episodes of rheumatic fever cause cumulative valve damage, which is why surveillance continues even after a reassuring first scan, alongside long-term antibiotic prophylaxis decided by the treating team.

References

• CDC: About Rheumatic Fever
• NHS: Rheumatic fever
• WHO: Rheumatic heart disease fact sheet
• NHS: Electrocardiogram (ECG)

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.