ECG criteria
- R wave amplitude in V3 ≤ 2–3 mm (according to various authors) is one of the frequently used empirical thresholds, neither the only one nor validated as an independent diagnostic criterion
- Evaluate the general trend of R wave progression rather than a strict sequence of R(V1) < R(V2) < R(V3) < R(V4): minor amplitude fluctuations between adjacent leads do not indicate PRWP by themselves
- A late transition zone (R = S), especially after V4, supports the diagnosis of PRWP, but there is no single universally accepted criterion for its location; a transition in V3 or V4 can be a variant of normal
- Sometimes combined with deep S waves persisting up to V5–V6
- Pathological Q wave in contiguous anterior leads according to standardized criteria: in V2–V3 — duration ≥ 0.02 s or QS complex; in I, II, aVL, aVF, V4–V6 — Q ≥ 0.03 s and depth ≥ 1 mm, or QS in any two contiguous leads of this group. The presence of such Q/QS increases the likelihood of prior myocardial infarction, but does not prove it by itself — assessment of recording technique, dynamics, and clinical context is required
- No ST-T elevation or dynamics typical for acute ischemia
- Comparison with prior ECGs: whether the finding is stable or new carries fundamentally different interpretations
What it looks like on ECG
Normally, the R wave typically increases from V1 to V4: in V1 it is small or absent (rS complex), the transition zone (the point where R becomes larger than S) is most often located in V3–V4, and then the R amplitude may slightly decrease in V5–V6. The S wave, conversely, gradually decreases and becomes small, especially by V4–V6. In healthy individuals, the location of the transition zone varies significantly — it can be in V2, V3, V4, and less commonly later; isolated predominance of S in V3 (R < S) is not a sufficient sign of PRWP by itself if overall R progression is preserved. In PRWP, R growth is impaired — the R amplitude in V3 remains low (a threshold of ≤ 2–3 mm is typically cited, with slight variations among authors), and the transition zone shifts to V4–V5 or fails to form entirely. A combination of features is evaluated: R progression, the R/S ratio, and the location of the transition zone, rather than a single mandatory condition in an isolated lead.
Pattern variants:
- R does not grow at all, rS persists in all chest leads;
- R grows, but very slowly, reaching normal amplitude only in V5–V6;
- R increases, then suddenly drops in one of the leads (usually a technical cause — incorrect electrode position).
Isolated PRWP lacks pathological Q/QS waves meeting standardized criteria in the anterior leads; small or isolated q variants should be evaluated considering the recording technique and other signs, as QS in V1 alone is sometimes found without infarction. The ST segment and T wave are usually without acute dynamics unless the cause is ischemic.
| Lead | Typical normal | PRWP |
|---|---|---|
| V1 | rS | rS |
| V2 | rS/RS | rS, R is low |
| V3 | often R > S (variable) | R ≤ 2–3 mm, S is dominant |
| V4 | R dominates | transition zone here or later |
Mechanism
The amplitude and direction of the R wave in chest leads reflect how the depolarization wavefront of the interventricular septum and left ventricular walls projects onto the electrode. Normally, the septal depolarization vector is directed anteriorly and to the right (small r in V1), and then the main LV vector is directed to the left, inferiorly, and posteriorly, forming a growing R towards V3–V6.
PRWP occurs when this normal transition is disrupted: either due to the loss of electrically active myocardium of the anterior wall (scar), due to changes in heart geometry and position, or due to conduction blocks that alter the direction of the initial vector. Another frequent cause is technical: V1–V2 electrodes are placed too high, artificially mimicking PRWP without any myocardial pathology.
Causes
- Technical: incorrect (high) placement of V1–V2 electrodes
- Prior anterior or anteroseptal myocardial infarction (scar)
- Left ventricular hypertrophy (vector rotation and shift)
- Left bundle branch block — significantly alters R progression; left anterior hemiblock can alter initial vectors and complicate ECG interpretation, but is not considered a classical independent cause of isolated PRWP
- Dilated cardiomyopathy
- COPD, pulmonary emphysema (vertical axis and heart rotation)
- Dextrocardia, pronounced clockwise heart rotation
- Obesity, high-standing diaphragm
- A variant of normal in some healthy individuals (without structural pathology)
Differential diagnosis
- Anterior myocardial infarction (scar): pathological Q/QS according to standardized criteria (in V2–V3 — duration ≥ 0.02 s or QS; in other anterior/lateral group leads — Q ≥ 0.03 s and depth ≥ 1 mm, or QS in two contiguous leads), often combined with inverted T waves, increases the probability of prior infarction, but is not a sufficient criterion by itself — electrode placement verification and clinical-instrumental correlation are required; the absence of Q also does not rule out infarction. PRWP and post-infarction scar can coexist.
- Technical electrode placement error: high position of V1–V2 mimics PRWP; verified by repeat recording with correct electrode placement.
- Clockwise rotation: transition zone is shifted to the right without scar signs, frequently in COPD — an independent variant of normal or a consequence of underlying lung disease.
- Right ventricular hypertrophy: can produce a similar pattern with S wave predominance in left chest leads, but is usually accompanied by right axis deviation and other signs of RV overload.
- ECG signs of acute anterior ischemia (de Winter waves, Wellens syndrome): distinguished by ST-T dynamics and symmetrical T wave changes rather than just low R waves.
Clinical significance and management
PRWP is a nonspecific finding: by itself, it is not a diagnosis and does not point to a specific disease. Its clinical significance is determined by the context.
The physician should:
- In the presence of chest pain, hemodynamic instability, or ST-T dynamics — act immediately according to the ACS protocol: serial ECGs, serial high-sensitivity troponin, urgent clinical evaluation. Routine echocardiography in this situation does not replace prompt assessment.
- Compare with previous ECGs — if the finding existed previously without dynamics, the likelihood of acute pathology is low.
- Check the recording technique — repeat the ECG with controlled V1–V2 electrode placement.
- Look for concomitant signs of infarction: pathological Q waves according to standardized criteria, ST-T dynamics, correlation with clinical picture.
- Evaluate the electrical axis, signs of LV/RV hypertrophy, bundle branch blocks — they alter the interpretation.
- If structural pathology (scar, cardiomyopathy) is suspected without acute symptoms — refer for echocardiography as a supplement to the assessment, not as a replacement.
Isolated stable PRWP without clinical symptoms and without ST-T dynamics generally does not require emergency actions, but deserves mention in the report and correlation with medical history.
Common interpretation errors
- Interpreting PRWP as an independent diagnosis rather than a descriptive sign that requires context.
- Failing to check the V1–V2 electrode placement technique before drawing clinical conclusions.
- Assuming that the absence or presence of Q waves definitively rules out or confirms a post-infarction scar — assessment based on standardized criteria for Q wave duration and depth, adjacent leads, dynamics, and clinical context is required.
- Ignoring comparison with prior ECGs, which often immediately alleviates concern.
- Limiting evaluation to routine echocardiography in the presence of new PRWP with ACS symptoms instead of immediate triage via the protocol.
- Failing to account for concomitant changes (electrical axis, hypertrophy, blocks) that explain the finding without an ischemic cause.
1. Which criterion is most frequently used to define poor R wave progression in V3?
Low R-wave amplitude in V3 (usually ≤ 2–3 mm) is one of the frequently used measurable PRWP criteria, although there is no single standard.
2. Which of the following increases the likelihood of a prior anterior myocardial infarction rather than isolated PRWP?
QS in V2–V3 or Q duration ≥ 0.02 s in these leads corresponds to standardized criteria for a pathological Q wave and increases the probability of a prior myocardial infarction, although it requires additional clinical and instrumental correlation.
3. Which cause of PRWP is considered purely technical and is resolved by repeat recording?
Incorrect (too high) placement of chest electrodes V1–V2 is a frequent technical cause of a false PRWP pattern.
Frequently asked questions
What is considered poor R-wave progression?
PRWP is a descriptive, non-specific pattern without a single validated threshold. Most commonly, an R-wave amplitude in V3 of no more than 2–3 mm is used as one of the empirical criteria, but it cannot be applied in isolation: the overall R-wave progression between V1–V3, the R/S ratio, and the position of the transition zone (normal or shifted to V4 and beyond) are also taken into account. Exact thresholds vary among authors; there is no universally accepted single criterion.
Is poor R-wave progression on the ECG dangerous?
The sign itself is non-specific and is not automatically dangerous. The risk is determined by the underlying cause: if it is a scar from a prior anterior myocardial infarction or a sign of cardiomyopathy, the significance differs from that of a technical electrode placement error or a normal variant.
How to distinguish PRWP from anterior myocardial infarction?
Pathological Q/QS waves according to standardized criteria (in V2–V3 — duration ≥ 0.02 s or QS complex; in other anterior and lateral leads — Q ≥ 0.03 s and depth ≥ 1 mm, or QS in two adjacent leads), often with inverted T waves, increase the likelihood of a prior myocardial infarction, but do not confirm it on their own. History, previous ECGs, clinical picture, echocardiography, and, if necessary, cardiac MRI are required; the absence of Q waves does not exclude myocardial infarction, and PRWP and a scar can coexist.
Can incorrect electrode placement produce a PRWP pattern?
Yes, this is one of the most common causes. Too high placement of electrodes V1–V2 distorts the QRS complex morphology and simulates poor R-wave progression. A repeat recording with the correct electrode position resolves the issue.
Is additional testing necessary when PRWP is found?
If the finding is new and accompanied by chest pain, instability, or ST-T dynamics, immediate evaluation according to the ACS protocol with serial troponin is required, rather than just routine echocardiography. An isolated stable finding without symptoms usually does not require emergency measures, but deserves correlation with medical history and, if necessary, echocardiography.
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Related terms
More in the section «Basics: waves, intervals, axes»
Sources
- Goldberger's Clinical Electrocardiography, latest edition
- Surawicz B., Knilans T. Chou's Electrocardiography in Clinical Practice
- Orlov V.N. Guide to Electrocardiography
- AHA/ACCF/HRS Recommendations for the Standardization of ECG, 2009
Educational material for medical students and physicians. Does not replace clinical guidelines and physical examination; the ECG must always be interpreted in conjunction with the clinical picture.