Heart Attack Misdiagnosis Lawsuits: Missed MI in the Emergency Department

Why Heart Attacks Get Missed

Acute coronary syndrome is the prototypical mismatch between textbook teaching and clinical presentation. The standard medical school description (substernal pressure radiating to the left arm with diaphoresis in a middle-aged man) is the minority presentation. The actual presentation in a busy ED is heterogeneous, and the heterogeneity is exactly where the diagnostic anchor goes wrong.

• Atypical symptoms outnumber typical. Particularly in women, diabetics, and elderly patients. Jaw pain, neck pain, back pain (especially interscapular), nausea and vomiting alone, isolated dyspnea, isolated fatigue, syncope, and indigestion symptoms are all documented presentations of acute MI. The same atypical-presentation problem drives recognition failure in elderly patients with sepsis presenting as confusion or weakness; the pattern is not unique to cardiac care.
• Risk factors are not always present. A young patient with no traditional risk factors can still have an MI from spontaneous coronary artery dissection, cocaine use, or a paradoxical embolus. Absence of risk factors is not a workup substitute.
• The initial EKG can be normal or nearly normal. A first EKG that is normal does not rule out acute MI. Up to a third of NSTEMIs have normal or nondiagnostic initial EKGs. Serial EKG is part of the standard of care for ongoing chest pain.
• The initial troponin can be negative. Particularly within the first 1 to 3 hours of symptom onset. Serial troponins at intervals dictated by the institution's chest pain pathway are required, not optional.
• Diagnostic anchoring closes the case prematurely. A patient given a working diagnosis of anxiety, GERD, costochondritis, or musculoskeletal pain often has subsequent data filtered through that diagnosis rather than triggering reconsideration.

The patterns that produce missed MI also produce missed ED diagnoses generally. Our ER malpractice and emergency-room misdiagnosis overview covers the institutional triage, anchoring, and discharge breaches that recur across all the most-litigated ED misses.

EKG Pitfalls That Drive Litigation

EKG interpretation errors account for a large share of missed MI claims. The recurring pitfalls:

• Posterior STEMI. ST elevation in the posterior leads (V7-V9) appears as ST depression with tall R waves in V1-V3 on a standard 12-lead. The standard 12-lead is not designed to make a posterior STEMI obvious; the ED is expected to order posterior leads when the precordial picture suggests posterior involvement. Missing a posterior STEMI is a recurring breach.
• Right ventricular STEMI. Inferior STEMI (ST elevation in II, III, aVF) requires evaluation for right ventricular involvement with right-sided leads (V4R). RV infarct changes management (avoid nitrates, give fluids).
• STEMI in the setting of LBBB. Left bundle branch block obscures the standard STEMI criteria. Sgarbossa criteria (with subsequent modified Sgarbossa) provide the analytic framework. Missing a STEMI in LBBB by assuming "LBBB hides MI" is a documented breach.
• Wellens syndrome. Biphasic or deeply inverted T waves in V2-V3 in a pain-free patient indicate critical proximal LAD stenosis. The classic Wellens pattern requires cardiac catheterization, not stress testing. Missed Wellens leads to anterior wall STEMI within days.
• Hyperacute T waves. Tall, broad, peaked T waves are the earliest EKG change in acute STEMI, preceding the ST elevation. Often missed as nondiagnostic, then progresses to STEMI hours later.
• Isolated lead changes. Subtle ST elevation in a single lead, particularly aVL, can indicate high lateral MI. Easily missed when read against the rest of an otherwise unremarkable tracing.
• Failure to obtain a prior EKG for comparison. Many subtle changes are obvious when compared to a prior baseline. Failure to pull a prior EKG when one exists is a workflow breach.

Troponin Testing and the Time Course

Cardiac troponin is the gold-standard biomarker for myocardial injury. Modern high-sensitivity troponin assays (hs-cTnT, hs-cTnI) detect concentrations below the 99th percentile of healthy populations and have changed the standard of care.

• A single troponin is not adequate to rule out MI in most pathways. Serial measurement at the institution's pathway intervals (often 0 and 1 hour or 0 and 3 hours with high-sensitivity assays) is required.
• A normal or low initial troponin does not exclude acute MI within the first 3 hours of symptom onset. Patients presenting early may have a negative first troponin and a clearly positive second.
• A rising or falling troponin pattern is the diagnostic criterion. A single elevated troponin can reflect chronic structural disease; an acute rise establishes acute injury.
• Chronic troponin elevations (chronic kidney disease, heart failure, sepsis, PE) require interpretation in clinical context. A baseline elevated troponin is not by itself evidence of acute MI but does not rule it out either.

Discharging a chest pain patient after a single negative troponin without completing the serial measurement is one of the most-litigated patterns. Cases frequently involve the patient returning hours later with completed infarct.

Chest Pain Pathways and Risk Stratification

Modern emergency departments operate chest pain pathways built around validated risk-stratification tools. The HEART score (History, EKG, Age, Risk factors, Troponin) is the most widely deployed; TIMI and GRACE scores are also used. A pathway-driven disposition is the standard of care; bedside gestalt is not. The same pathway-driven model governs stroke recognition and treatment-window decisions, and the litigation framework rests on the same documented-vs-bypassed pathway analysis.

The chest pain pathway typically requires:

• EKG within 10 minutes of arrival.
• Targeted history and exam.
• Initial troponin and serial troponin measurement per institutional protocol.
• Risk stratification using HEART or equivalent.
• Disposition: low risk (discharge with primary care follow-up), intermediate risk (observation with stress testing or coronary CT), high risk (admission with cardiology consultation).
• Documented return precautions and follow-up plan.

In a missed-MI case, the chest pain pathway is the evidence. When hospitals and doctors fail, families deserve answers.

Bypassing the pathway, using a non-validated bedside impression in place of risk stratification, or stopping the workup midway are common breach patterns. Plaintiff's emergency medicine and cardiology experts deconstruct the workup and identify the missed steps.

Cardiology Consult, Cath Lab Activation, and Door-to-Balloon Time

For confirmed STEMI, the standard of care is primary percutaneous coronary intervention within a target door-to-balloon time of 90 minutes (or door-to-needle time of 30 minutes for fibrinolytic therapy when PCI is not available). Door-to-balloon time is a tracked institutional metric. Failure to activate the cath lab when STEMI is identified, or delay in transfer to a PCI-capable facility, are documented breaches that drive significant cases.

For NSTEMI and unstable angina, the standard timing for invasive evaluation depends on risk stratification: very high risk (hemodynamic instability, mechanical complications, refractory chest pain, ventricular arrhythmia) requires emergent angiography; high risk requires angiography within 24 hours; intermediate risk requires angiography within 72 hours.

Causation and Damages in Missed MI Cases

Causation is the central battlefield. The defense argues that the eventual outcome would have happened regardless of timing, that the patient had pre-existing cardiac disease, or that the missed window did not change the infarct size.

The plaintiff's causation evidence:

• Time-from-symptom-onset to revascularization. Each hour of delay correlates with increased infarct size and worse left ventricular function.
• Ejection fraction at the conclusion of treatment. Compared to the EF that would have been preserved with timely intervention.
• Wall motion abnormalities on echocardiography. Document the extent of permanent myocardial injury.
• Subsequent treatment intensity. Need for surgical revascularization (CABG) vs primary PCI, mechanical circulatory support, ICD placement, heart failure care.
• Subsequent disease course. Heart failure progression, recurrent infarction, sudden cardiac death.

Damages categories:

• Past and future medical expenses (additional revascularization, ICD placement, heart failure medication and follow-up, transplant evaluation in advanced cases)
• Lost wages and earning capacity (often substantial for working-age patients with significant LV dysfunction)
• Pain and suffering (subject to state non-economic damage caps in many jurisdictions)
• Wrongful death damages (see our wrongful death lawyer overview for state procedure)
• Survival damages (pre-death pain and suffering of the decedent in fatal cases)

Medicine is complicated. Accountability should not be.