Use of ECGs in Assessment of Acute Posterior & Inferior MI’s

Background 12-lead ECGs to detect STEMI Posterior & Right-sided ECGS: How quickly are they performed? Are serial ECGs done for evolving changes? Posterior & Right-sided ECGS: Uncertainty re: indications & how to perform them How could they affect management? How many are being performed? Are we doing them appropriately?

Posterior AMI Most often occurs with inferior infarct Diagnosis reliant upon recognition of reciprocal changes in chest leads Reciprocal changes are insensitive and non-specific ABC of clinical electrocardiography Francis Morris, William J Brady (BMJ 2002;324:831–4)

Right Ventricular AMI May manifest as cardiogenic shock Commonly a complication of inferior AMI Important to identify as treatment differs from shock caused by LVF Clinical triad in patients with Inferior AMI (sensitivity<25%): Hypotension, Clear Lung fields, JVP Tx: Maintain Rt Ventricular Pre-load Avoid vasodilators; Opiates, nitrates, diuretics, ACEi’s etc IV fluids with careful monitoring ABC of clinical electrocardiography Francis Morris, William J Brady (BMJ 2002;324:831–4)

12-lead ECG Guidelines A 12-lead ECG should be performed and shown to an experienced emergency physician within 10 minutes of ED arrival on all patients with chest discomfort (or anginal equivalent) or other symptoms suggestive of STEMI. (Level of evidence: C) [1] If the initial ECG is not diagnostic of STEMI but the patient remains symptomatic, and there is a high clinical suspicion for STEMI, serial ECGs at 5- to 10- minute intervals or continuous 12-lead ST-segment monitoring should be performed to detect the potential development of ST elevation. (Level of evidence: C) [1] 1) American College of Cardiology Guidelines 2004 (JACC Vol 44 No 3 2004:671-719)

Post & Inf MI Guidelines In patients with inferior STEMI, right-sided ECG leads should be obtained to screen for ST elevation suggestive of right ventricular infarction. (Level of evidence: B) [1] Right ventricular infarction should be suspected in hypotensive patients with symptoms suggestive of AMI [2] Patients with ST depression of 1mm or more in 2 or more contiguous non-standard leads (V4R through V6R, V7 through V9) in patients with clinical presentation suggestive of isolated right ventricular or posterior AMI should be assessed for fibrinolytic therapy [3]

Audit Standards All patients with CP/STEMI symptoms -> 12 lead ECG within 10 minutes If non-diagnostic initial ECG -> serial ECGs at 5-10 minute intervals Inferior STEMI -> Right-sided leads to screen for Rt Ventricular infarct Hypotensive (systolic BP < 90mmHg) patients presenting with ?STEMI/NSTEMI -> Rt-sided leads Patients with reciprocal change (>1mm ST depression in 2 contiguous anterior leads) ?isolated Right/Posterior MI -> Right/Posterior leads

Methodology Retrospective audit Population identified via cardiology records: STEMI & NSTEMI patients admitted July-November 2005 A&E Cards retrieved Notes audited using standardised pro forma Data collated and interpreted using Excel spreadsheet

Sample Population 71 total patients (21 STEMI, 50 NSTEMI) Notes found for 38 patients n NSTEMIs n STEMIs n antero-lateral n inferior n posterior n infero-posterior 29 men (76%), 9 women (24%) Mean age 67 years (Minimum 42, Max 93)

Main Findings: Initial ECGs 1st ECG performed within 10min in n out of n cases = n% STEMI (n=n) n% within 10 min, mean = 5 min NSTEMI (n=n) n% within 10 min, mean =16 min

Main Findings: Serial ECGs 2nd ECG in n out of n NSTEMIs no time on ECG n=n within 10min in n out of n cases (n%) median time = n min 3rd ECG in n out of n NSTEMIs no time on ECG n=1

Main Findings: Post & RV ECGs V3R-V6R performed in n out of n cases with inferior changes on 12 lead ECG = n% V3R-V6R performed in n out of n cases with hypotension = n% V3R-V6R/V7-V9 performed in n out of n cases with reciprocal changes on ECG = n%

Additional Findings A&E notes unavailable for n cases ECGs not in notes for n out of n cases Apparent troponin negative cases (n=n) Presenting Complaints: STEMI; n = Chest pain, n = Back pain NSTEMI; n = Chest pain, n = SOB, n = collapse, n = hypertension, n = unwell, n = blocked catheter!

Limitations of this Audit Retrospective: relies upon complete & accurate A&E notes (eg all ECGs available in notes) Comparatively small audit population Arrival time taken from ‘booking in’ time in > 50% as LAS arrival not always documented  ?underestimated time to ECG ECG timings do not include time taken to show to medical staff  ?underestimated

Recommendations Guidelines re: ’10 minute target’ highlighted in triage area Teaching session for ED staff (doctors and nurses) re: indications for right/post ECG leads and how to perform them Posters in majors/resus with summary of above Re-audit 4/12.

References American College of Cardiology Guidelines 2004 (JACC Vol 44 No 3 2004:671-719) Chapter in ‘Emergency Medicine: A Comprehensive Study Guide’ 5th Edition, Judith E Tintinalli Clinical policy: critical issues in the evaluation and management of adult patients presenting with suspected acute myocardial infarction or unstable angina. Ann Emerg Med. May 2000;35:521-544 ABC of clinical electrocardiography Francis Morris, William J Brady (BMJ 2002;324:831–4)