10 common heart disease and ecg change

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10 common heart diseases ECG changes summary 2024

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10 Common Heart Diseases and Their ECG Changes

Here is a systematic overview of 10 major cardiac conditions and their characteristic electrocardiographic findings, drawn from Braunwald's Heart Disease, Goldman-Cecil Medicine, Medical Physiology, and other authoritative sources.

1. ST-Elevation Myocardial Infarction (STEMI)

ECG Evolution (3 stages):

Stage	Change	Timing
Hyperacute	Peaked (hyperacute) T waves	Minutes
Acute	ST-segment elevation in leads over affected territory	Hours
Evolving	T-wave inversion, pathological Q waves (>40 ms, >25% R height)	Hours-days
Old	Persistent Q waves, T-wave normalization	Weeks-permanent

Localizing leads:

Inferior (RCA): ST elevation in II, III, aVF
Anterior (LAD): ST elevation in V1-V4
Lateral (LCx): ST elevation in I, aVL, V5-V6
Posterior: ST depression in V1-V3 (reciprocal), tall R in V1

Mechanism: Anoxic injury depolarizes epicardial cells, raising their resting potential relative to normal cells - this produces the apparent ST elevation. Electrically silent infarcted tissue causes the depolarization vector to point away, inscribing deep Q waves. - Medical Physiology, p. 735

2. NSTEMI / Unstable Angina

ECG Changes:

ST-segment depression (horizontal or downsloping, ≥0.5 mm)
T-wave inversion (deep, symmetric)
May have no ECG changes at rest (only during ischemia)
No pathological Q waves (by definition - no full-thickness necrosis in NSTEMI)

Key distinction: NSTEMI requires elevated troponin + these ECG changes; unstable angina has the same ECG picture but normal biomarkers. - Tintinalli's Emergency Medicine, block 4

3. Atrial Fibrillation (AF)

ECG Changes:

Absent P waves - replaced by irregular fibrillatory baseline (f-waves, >350/min, variable morphology)
Irregularly irregular RR intervals - the hallmark
Narrow QRS (unless aberrant conduction or bundle branch block)
Ventricular rate typically 100-180 bpm if uncontrolled

Associated findings: LVH if hypertensive cause; mitral valve disease pattern (broad notched P in sinus rhythm before AF onset)

4. Atrial Flutter

ECG Changes:

Sawtooth flutter waves (F-waves) at 250-350/min, most visible in II, III, aVF, V1
Regular atrial rate ~300/min with fixed AV block ratio: most commonly 2:1 (ventricular rate ~150 bpm), also 3:1 or 4:1
Narrow QRS (unless aberrancy)
No isoelectric baseline between flutter waves

Atrial flutter and fibrillation ECG patterns

ECG tracings showing sinus tachycardia, atrial fibrillation, and atrial flutter - Braunwald's Heart Disease

5. Acute Pericarditis

ECG Changes (4 stages):

Stage	Finding
Stage 1 (days 1-2)	Diffuse ST elevation (saddle-shaped/concave up) in most leads except aVR and V1; PR depression in limb leads and V4-V6; PR elevation in aVR
Stage 2 (days/week)	ST normalization, PR depression persists
Stage 3	T-wave inversion (diffuse)
Stage 4	ECG normalizes

Key distinction from STEMI: Pericarditis ST elevation is diffuse (all territories), concave-up ("saddleback"), and always accompanied by PR depression. STEMI is focal with reciprocal ST depression. - Goldman-Cecil Medicine, block 8

6. Heart Failure with LVH (e.g., Hypertensive Heart Disease)

ECG Changes:

Left ventricular hypertrophy (LVH) by voltage criteria:
- Sokolow-Lyon: S in V1 + R in V5/V6 ≥35 mm
- Cornell: R in aVL + S in V3 >20 mm (women) or >28 mm (men)
LV strain pattern: ST depression + T-wave inversion in I, aVL, V5-V6 (lateral leads)
Left axis deviation
Left bundle branch block (LBBB) in advanced disease
Broad notched P waves (P-mitrale) indicating left atrial enlargement
Tintinalli's Emergency Medicine; Robbins & Kumar Basic Pathology, block 4

7. Aortic Stenosis

ECG Changes:

LVH with strain pattern (ST depression and T-wave inversion in V5-V6, I, aVL) - the pressure overload signature
Left axis deviation
Left bundle branch block - as conduction system is compressed
PR prolongation possible
Atrial fibrillation in late/decompensated disease

"Typical ECG abnormalities associated with aortic stenosis include left ventricular hypertrophy (often with a strain pattern), left axis deviation, and left bundle branch block." - Miller's Anesthesia, block 11

8. Hypertrophic Cardiomyopathy (HCM)

ECG Changes:

LVH voltage criteria (often dramatic)
Deep, narrow Q waves in inferior (II, III, aVF) and lateral leads (I, aVL, V5-V6) - "septal Q waves" from hypertrophied septum, not infarction
T-wave inversion - especially in lateral leads
Left axis deviation
Atrial fibrillation - common complication (left atrial enlargement)
Bundle branch blocks in some
WPW pattern occasionally co-exists

9. Pulmonary Embolism (PE)

ECG Changes:

The classic S1Q3T3 pattern: S wave in lead I, Q wave in lead III, T-wave inversion in lead III - reflecting acute right heart strain
Sinus tachycardia - most common finding
New right bundle branch block (RBBB) - complete or incomplete
Right axis deviation
Right ventricular strain: T-wave inversion in V1-V4
P pulmonale: peaked P waves in II (right atrial strain)
ST changes mimicking anterior MI possible
Note: ECG is often non-specific; sensitivity for S1Q3T3 alone is low

10. Wolff-Parkinson-White (WPW) Syndrome

ECG Changes (in sinus rhythm):

Short PR interval (<120 ms) - early ventricular activation via accessory pathway
Delta wave - slurred upstroke of the QRS (initial slow conduction through working myocardium before His-Purkinje takes over)
Wide QRS (≥120 ms) - total conduction time prolonged
Pseudo ST-T changes - secondary repolarization abnormalities (not ischemia)
Pseudo-infarction Q waves in some leads

During tachycardia (AVRT):

Orthodromic (most common): narrow QRS, regular tachycardia 150-250 bpm
Antidromic: wide QRS tachycardia (dangerous if AF develops - can degenerate to VF)

"The presence of ventricular preexcitation, as manifested by a short PR interval and a delta wave, establishes the likely diagnosis of Wolff-Parkinson-White." - Goldman-Cecil Medicine, block 6

Quick Reference Summary Table

Condition	Key ECG Feature
STEMI	ST elevation (territory-specific) → Q waves
NSTEMI/Unstable Angina	ST depression, T-wave inversion, no Q waves
Atrial Fibrillation	Absent P waves, irregularly irregular rhythm
Atrial Flutter	Sawtooth F-waves ~300/min, 2:1 AV block
Acute Pericarditis	Diffuse ST elevation (concave), PR depression
Hypertensive Heart Disease/Heart Failure	LVH voltage + lateral strain pattern
Aortic Stenosis	LVH + strain, LBBB, left axis deviation
Hypertrophic Cardiomyopathy	LVH + deep septal Q waves in inferior/lateral leads
Pulmonary Embolism	S1Q3T3, sinus tachycardia, new RBBB, RV strain
WPW Syndrome	Short PR + delta wave + wide QRS

Sources: Medical Physiology (Boron & Boulpaep); Goldman-Cecil Medicine; Braunwald's Heart Disease; Miller's Anesthesia; Tintinalli's Emergency Medicine; Robbins & Kumar Basic Pathology; Fuster and Hurst's The Heart

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ECG Reference Guide

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What's inside the PDF (13 pages):

Section	Content
Cover page	Title, subtitle bar, full table of contents with all 10 conditions
Quick Reference Summary	Single-table overview of every condition's most diagnostic ECG finding and lead location
10 individual condition pages	One page per condition (see below)
Lead Localisation Reference	Territory → leads → culprit artery → reciprocal changes table
Heart Block Summary	1st, 2nd (Mobitz I/II), and 3rd degree AV block comparison table

Each condition page includes:

Color-coded section header with condition number
Full-width rhythm strip on ECG grid with calibration pulse - rendered with accurate waveform morphology for each disease (AF shows chaotic fibrillatory baseline + irregular QRS; flutter shows sawtooth F-waves; WPW shows delta wave and short PR; STEMI shows ST elevation + wide Q; etc.)
Key ECG features (6 bullet points)
Mechanism - why the ECG looks the way it does
Annotated waveform close-up showing the key abnormality

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