Differentiating between Pericarditis, Benign Early Depolarisation and ST Elevation Myocardial Infarction can sometimes be difficult. Pericarditis is initially a clinical diagnosis. We must beware not to miss ischaemia. Morphology of the ST segments We should never make generalisations, however convex is usually worst than concave. I used to teach this as the ‘smiley’ and ‘sad’ faces. Case 1 A 35 yo male presents with palpitations and pleuritic chest pain. He’s recently had a viral illness but has no other medical history. At 1am in the morning, the patient was woken by palpitations. He now complains of left sided chest pain and dyspnoea. His vitals are normal. His ECG is shown below. What is the diagnosis? Is it pericarditis, or Benign Early Repolarisation(BER) or ST elevation myocardial Infarction(STEMI)? ANSWER If we analyse this ECG using the ecg in 20 seconds approach (Cardiac Course): Rate: 84 bpm P waves: Upright in I, II and inverted in aVR = leads in right place and normal sinus rhythm QRS: Not too tall, not too small, normal morphology and no clumping ST-T segments Saddle shaped elevation in II, aVF, V4-6 – this widespread ST elevation with no reciprocal changes ie., no reciprocal ST depression, indicates pericarditis. There is ST depression in aVR as well as PR elevation- This indicates pericarditis. Intervals: PR and QT are normal, but there is PR depression in some leads What other features do we see in this ECG? 1 There is J-point notching in V4 which is more consistent with BER. 2 The ST Segment/T wave ratio is ¼ = 0.25- this doesn’t help us as >0.25 = pericarditis. HOW DO WE DIAGNOSE PERICARDITIS? A December 2014 NEJM article(1) provides a good clinical practice review of this topic. To diagnose pericarditis we need a minimum of 2 of the following 4 criteria: 1 Typical chest pain -Especially pleuritic pain, preacordial or retrosternal, relieved by sitting forward -Pain that radiates to trapezius ridge(2) (considered pathognomonic) -Remember that the pain may not always, and I find is not often typical. 2 Pericardial Friction Rub– this is transient 3 Typical ECG changes ST elevation across several territories- this should be concave PR depression PR depression is very specific for pericarditis. It is a result of subepicardial injury. PR depression occurs in all leads except aVR and V1. In these two leads the PR segment may be elevated (Cardiol Clin 1990, 8:639.44) Other causes of PR depression include: Atrial infarction Abnormal repolarisation No reciprocal ST depression, except in aVR + V1 The ST-T ratio is important ST/T >0.25 in V6 suggests pericarditis The ST/T ratio can also be used to differentiate early repolarization from acute pericarditis. Measure ST elevation in millimetres in V6, from the isoelectric line, then measure the tallest point of the T wave, in millimeters, from the isoelectric line. If ST/T is >0.25 in V6 it suggests acute pericarditis (Circulation 198; 65:1004-9) 4 Pericardial effusion -A significant effusion is usually described as > 20mm in width STAGES OF PERICARDITIS All 4 stages occur in less than 50% of patients. ST segment elevation in pericarditis is usually concave as compared to the convex shape of infarction. There is no arterial territorial distribution as in myocardial infarction, no reciprocal changes, no Q waves (unless there has been a previous infarction) and no T wave inversion when the ST segments are elevated. My diagnosis in this case is that this is probably acute pericarditis on the background of BER. How to differentiate Pericarditis from Benign Early Repolarisation (BER)? Requirements for pericarditis -T waves normal, non prominent -No fish hook, ie., J point, especially in V4 -Spodick’s Sign: There is a downslope of the ST-T segment. -ST segment elevation/T wave is >0.25 in pericarditis Differentiating STEMI from Pericarditis or BER? -If there is ST depression in any other lead except aVR, it is iscahemia. -ST elevation III>II is a STEMI -QR-T Sign occurs in STEMI So what do we do with this patient? His clinical presentation points to a pericarditis. There are changes in his ECG that support that, however there are also changes that support BER. However there is no evidence of a STEMI. -My approach is to treat him as a pericarditis. Patients with BER may also have pericarditis. What causes pericarditis? Viral infections are the main cause, however they may also be due to bacteria and tuberculosis. It can be due to immune causes such as SLE. It can also be caused by trauma, medications and patient may present post MI. This patient volunteered that he had a recent viral illness, which helps us with the diagnosis. Any other investigations to do? Labs 1 Troponin- A very mildly raised troponin can occur in pericarditis, however more than a slight bump in troponin may indicate ischaemia, or a progression of perimyocarditis and further to myopericarditis. These are very sick patients. 2 CRP- this gives an indication of the progress of the disease and may be helpful if admitted Radiology 1 CXR- may show a widened mediastinum and alert you to a pericardial effusion 2 ECHO – we can do a bedside echo looking for a significant pericardial effusion. It will also show wall motion abnormalities if there is any question of ischaemia. What is significant is described as being >20mm in width. These are only present in about 3% of patients(3). If a patient is going home they probably can also have a more formal outpatient ECHO. What is the treatment of Pericarditis? 1 NSAIDS 600-800mg 6-8/24 or Aspirin 2-4g daily in divided doses. Continue for 1 week 2 Colchicine 0.5mg bd if >70kg and 0.5mg daily if <70kg. Continue for 3 months(4) I would also add a proton pump inhibitor. What about steroids as the anti-inflammatory agent of choice. There is evidence to say that it results in a greater rate of recurrence(3). Who can we send home? The presence of any of these 5 factors, determine the need for admission: -Fever > 38o C; -Subacute onset; -Large pericardial effusion; -Cardiac tamponade; and -Lack of response to aspirin or non steroidal anti-inflammatory drugs (NSAIDs) after at least 1 week of therapy. Case 2 A 52 yo male presents with atypical chest pain for 3-4 hours. He has had a vague feeling of chest heaviness for the whole day and has had an episode of palpitations. His only past medical history is of hypertension. Examination is normal, with dual heart sounds and no reproducible chest pain on palpation. Lungs are clear and abdo is soft. An ECG is done as shown below. which of the following diagnoses does this represent?: (a) STEMI (b) Ischaemia (c) Pericarditis (d) Benign Early Repolarisation Answer This is not a straightforward ECG, as few of them are. My diagnosis and the diagnosis we gave this patient was pericarditis. Below is my thinking, plus also view the image below this: It is not a STEMI and although there is ST elevation in multiple regions there are no reciprocal changes to be seen In terms of just plain ischaemia, there are very few changes here. The diagnosis of pericarditis is the most probable for the following reasons: There is ST elevation in multiple territories, with no reciprocal changes There is a down-sloping baseline, indicating Spodick’s Sign There is PR depression in several leads except aVR and V1 where we would expect pr elevation and it is present. The only thing not present which would have made it a ‘slam dunk’ diagnosis is that the ST/T ratio in V6 is not > 0.25 It is not likely to be benign early repolarisation as there is no J point to be seen especially in V4 REFERENCES LeWinter M.M. Acute Pericarditis. NEJM 371;25, Dec 18 2014 pp 2410-2416 Maisch B et al. Guidelines on the diagnosis and management of pericardial diseases executive summary. Task Force onthe Diagnosis and Management of Pericardial Diseases of the European Society of Cardiology. Eur Heart J 2004;25:587-610 Imazio M et al. Treatment with aspirin, NSAID, corticosteroids and colchicine, in acute and recurrent pericarditis. Heart Fail Rev 2013;18;355-360 Imazio M et al. A randomised trial of colchicine for acute pericarditis. NEJM 2013;369:1522-1528
