ECG criteria
- Down-sloping ST-segment depression in I, aVL, V5–V6
- Asymmetrical negative T wave in the same leads — slow downstroke, fast upstroke
- The direction of ST depression and T inversion is opposite to the main QRS vector (discordant relative to R)
- LVH voltage criteria are often present but not mandatory: Sokolow-Lyon index — S(V1) + R(V5 or V6) ≥35 mm; Cornell voltage — R(aVL) + S(V3) >28 mm in men and >20 mm in women; Cornell product — (R(aVL) + S(V3)) × QRS duration >2440 mm·ms
- In V1–V3, sometimes a slight ST elevation and a positive or biphasic T wave with a deep S wave; this is nonspecific, not a mandatory criterion, and its absence does not rule out strain
- Left axis deviation in marked LVH
- Prolonged intrinsicoid deflection time in V5–V6 (>0.05 s)
- According to the Romhilt-Estes criteria, "strain"-type ST-T changes score 3 points without digitalis and 1 point with digitalis
What it looks like on ECG
The pattern consists of two components: findings compatible with left ventricular hypertrophy (often, but not always, high QRS voltage) and secondary ST-T changes.
In the leads with a dominant R wave — I, aVL, V5–V6 — the ST segment is displaced downward as a down-sloping depression, transitioning into an asymmetrical negative T wave: the downstroke is gradual, and the upstroke is steep. This differs from the more symmetrical "coronary" T wave in ischemia, although the ST-T morphology is not completely reliable for differentiation.
In the right precordial leads V1–V3, where the S wave is dominant, a slight ST elevation and a positive or biphasic T wave are sometimes noted. This is a nonspecific finding — it is not used independently to diagnose strain and is not its mandatory component: identical changes in V1–V3 occur as a normal variant, in early repolarization, ischemia, and other conditions. The primary criterion is the left-sided changes: ST depression and T inversion in I, aVL, V5–V6.
| Leads | QRS | ST | T |
|---|---|---|---|
| I, aVL, V5–V6 | tall R (frequent) | down-sloping depression | asymmetrical (-) |
| V1–V3 | deep S | sometimes slight elevation (nonspecific) | (+) or biphasic, not mandatory |
The QRS axis is often deviated to the left, and the intrinsicoid deflection time in V5–V6 is prolonged (>0.05 s). QRS duration typically remains within normal limits, unlike in LBBB. Important: the ST-T strain pattern can also occur with borderline or normal QRS voltage — the low sensitivity of voltage criteria does not rule out the diagnosis.
Mechanism
In marked hypertrophy, the LV myocardium is thickened, and the muscle mass and, accordingly, the depolarization time and pathway are increased — hence the frequently high QRS voltage. Repolarization of the hypertrophied myocardium is altered secondarily: the direction and velocity of the repolarization wave change, and systolic intraventricular pressure increases ("systolic overload"), which shifts the ST-T vector. Relative subendocardial hypoperfusion due to a mismatch between coronary blood flow and increased muscle mass is considered a possible additional factor, but the strain pattern itself is primarily a consequence of altered depolarization and LV remodeling, rather than proof of ischemia. The resulting ST-T vector is directed oppositely (discordantly) to the main QRS vector — hence the ST depression and T inversion where R is tall.
Causes
- Arterial hypertension (most common cause)
- Aortic stenosis (pressure overload)
- Hypertrophic cardiomyopathy
- Coarctation of the aorta
- Prolonged LV overload in aortic regurgitation combined with hypertension
- Pronounced athletic remodeling (rare, usually without true strain)
Differential diagnosis
- Ischemia/subendocardial injury — strain typically produces a down-sloping ST depression and asymmetrical T-wave inversion, but identical changes also occur in ischemia; the down-sloping shape does not rule out ACS. Clinical presentation, serial ECG dynamics, and high-sensitivity troponin are decisive.
- LBBB — in LBBB, the QRS is wide (≥120 ms) with a characteristic morphology (broad notched R in V5–V6, absence of Q in lateral leads), rather than simple ST-T changes with a narrow QRS.
- Digoxin effect on ECG — saggy ST depression, whereas in the strain pattern the depression is down-sloping without "sagginess"; digoxin can mask or enhance the picture and reduces the specificity of ST-T changes in the Romhilt-Estes scoring system.
- Sgarbossa criteria / modified Sgarbossa (Smith) criteria — used for suspected MI in the setting of LBBB, not LVH with strain; these criteria are not validated for the LVH strain pattern.
- Hypertrophic cardiomyopathy — can produce very deep, giant negative T waves (especially in the apical form), not always a classic strain pattern.
Clinical significance and management
The strain pattern is not a standalone diagnosis, but an ECG finding associated with more pronounced LVH and an unfavorable prognosis (increased risk of stroke, heart failure, ventricular arrhythmias, sudden cardiac death). This association is described accounting for a number of factors, including hypertension, but the ECG pattern does not replace clinical evaluation and echocardiography, nor does it prove the duration of the process. The physician should:
- confirm LVH echocardiographically (LV mass, wall thickness);
- search for and correct the cause of the overload (hypertension, aortic stenosis);
- not rule out ACS solely based on the down-sloping shape of the ST segment or the presence/absence of LVH voltage criteria — in suspected ACS, serial ECGs, high-sensitivity troponin, comparison with prior ECGs, and evaluation of dynamics are necessary;
- consider strain as an unfavorable prognostic ECG sign and separately evaluate ECG criteria for LVH, such as the Sokolow-Lyon or Cornell indices.
Common interpretation errors
- Ruling out ACS solely based on the ST depression shape (down-sloping) or the presence of LVH voltage criteria — this must not be done; clinical presentation and dynamics are decisive.
- Expecting obligate high QRS voltage to diagnose strain — the ST-T pattern can occur even without overt voltage criteria.
- Ignoring digoxin therapy, which alters the shape of ST depression and reduces the specificity of the ST-T criterion in the Romhilt-Estes scale.
- Confusing it with LBBB when QRS duration is not accurately measured.
- Diagnosing the strain pattern solely by T-wave inversion without assessing the ST-segment shape and the direction of discordance.
1. What shape of ST-segment depression is characteristic of the LVH strain pattern in leads I, aVL, V5–V6?
Systolic LV overload is typically characterized specifically by down-sloping ST depression transitioning into an asymmetrical negative T wave.
2. What may be observed in leads V1–V3 in the LVH strain pattern?
In leads with a dominant S wave, the ST-T vector may be directed oppositely, producing a slight ST elevation, but this is a nonspecific finding rather than a mandatory strain criterion.
3. How does digoxin therapy affect the evaluation of ST-T abnormalities according to the Romhilt-Estes criteria?
Strain-type ST-T changes give 3 points in the absence of digitalis and 1 point if the patient is taking it, as digoxin reduces the specificity of this sign.
Frequently asked questions
How to distinguish the LVH strain pattern from myocardial ischemia?
In the strain pattern, ST depression is typically downsloping and the T wave is asymmetric (a gradual descending limb and a steep ascending limb), often accompanied by voltage criteria for LVH. However, a similar ST-T morphology also occurs in ischemia, so the shape of the changes and the presence of LVH do not reliably rule out ACS—the clinical picture, high-sensitivity troponin, and serial ECG dynamics play the decisive role.
Is the strain pattern dangerous in itself?
The pattern itself is not directly life-threatening, but it is associated with more pronounced LVH—an independent risk factor for stroke, heart failure, and sudden cardiac death. It requires echocardiography and correction of the cause of LV overload.
Can STEMI be diagnosed in the presence of the LVH strain pattern?
Diagnosis is difficult because baseline discordant ST-T changes are present. Comparison with a prior ECG, assessment of dynamics, and clinical evaluation are necessary; specific validated criteria (like those for LBBB) have not been developed for LVH, so decisions are made comprehensively.
How does the strain pattern differ from the effect of digoxin on the ECG?
With digoxin, ST depression usually has a sagging (scooped) shape, whereas with the strain pattern, it is downsloping without marked sagging. In the Romhilt–Estes criteria, ST-T changes give 3 points without digitalis and only 1 point when it is taken, as digoxin reduces the specificity of this sign.
Is echocardiography necessary when a strain pattern is detected on the ECG?
Yes, echocardiography confirms and quantitatively assesses LV hypertrophy (wall thickness, myocardial mass) and also helps rule out other causes of ST-T changes, such as hypertrophic cardiomyopathy or aortic stenosis.
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Related terms
More in the section «Hypertrophy and Chamber Enlargement»
Sources
- Goldberger A. Clinical Electrocardiography
- 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.