ST Segment Elevation: What It Means on an ECG

ST segment elevation on an electrocardiogram is an elevation of the ST isoline above the baseline (usually relative to the J-point—the transition point of the QRS complex into ST) in one or more leads. This elevation may be a sign of acute coronary artery occlusion (ST-elevation myocardial infarction), but it also occurs in other conditions: pericarditis, benign early repolarization, Brugada syndrome, takotsubo, hypertrophy, postinfarction aneurysm, etc. Therefore, "ST↑" is not a diagnosis, but a signal for a rapid analysis of the clinical picture and ECG patterns. [1]

It is critical to be able to distinguish life-threatening causes (primarily acute coronary occlusion) from mimics. Current guidelines for acute coronary syndromes (European Society of Cardiology, 2023; ACC/AHA, 2025) require immediate reperfusion in suspected ST-elevation infarction and recommend an aggressive approach when the time to primary percutaneous intervention can be minimal. Delay directly worsens the prognosis. [2]

However, excessive "Catlab activation" in the presence of intact coronaries is also a problem. ECG signs (ST shape, discordance, reciprocal changes), comparison of leads (III > II in inferior infarction), searching for ST depression outside aVR/V1, and special criteria for complex situations, such as the modified Sgarbossa criteria for left bundle branch block, can help here. [3]

This article outlines the approach: how to recognize dangerous elevation, how to conduct differential diagnosis, which tests and treatments are indicated at different points, and what new details have emerged in the latest recommendations. We deliberately combine a "quick fix" approach (minutes matter) with a sequential analysis of imitation cases. [4]

Epidemiology

ST-elevation myocardial infarction (STEMI) accounts for a minority of all acute coronary syndromes but accounts for the largest share of early mortality. In European and North American registries, the proportion of STEMIs among hospitalizations for acute coronary syndrome fluctuates between a quarter and a third, with timely reperfusion reducing in-hospital mortality. The updated ESC 2023 and ACC/AHA 2025 guidelines emphasize time goals: from first medical contact to the rescuer – a matter of tens of minutes. [5]

"Non-ischemic" ST elevations are even more common: early repolarization is common in young people (up to several percent of the population), often without any risk. Observational reviews indicate that most people with the typical "benign" pattern of early repolarization have minimal prognostic risk. It is important to distinguish this pattern from pericarditis and STEMI. [6]

Pericarditis as a cause of diffuse ST elevation occurs at any age; it usually has characteristic ECG features (diffuse ST elevation, "downsloping" PR isoline - PR depression) and a clinical picture. However, no single sign is absolutely specific, so the diagnosis is a combination of data. [7]

Other causes of ST elevation (Brugada syndrome, takotsubo, "posterior" infarction - with ST depression in V1-V3, and ST elevation when recording V7-V9) are less common, but critically important due to differences in tactics. For example, Brugada syndrome is an arrhythmogenic condition with a risk of sudden death, and posterobasal infarction requires "inverting the image" and/or placing additional leads. [8]

Reasons

The main dangerous cause is coronary artery occlusion with transmural ischemia (STEMI). ECG pattern: convex or horizontal ST elevation in adjacent leads, reciprocal ST depression in the "opposite" leads, rapidly rising troponins, and corresponding clinical symptoms. This condition requires immediate reperfusion. [9]

Pericarditis and myopericarditis produce diffuse ST elevations with PR depression, often without reciprocal depression (except in aVR/V1), often with a "sloping" baseline (Spodick's sign). However, approximately 10-12% of infarctions can also have PR depression, so STEMI should always be ruled out first. [10]

Benign early repolarization (“high take-off”) is typical in young individuals: ST elevations in the anterolateral leads with a notch at the J-point, absence of reciprocal depression, and pattern stability over time. Most are benign and do not require treatment. [11]

Other causes include: Brugada syndrome (cow-shaped/saddle-shaped elevation in V1-V3), takotsubo (often ST elevations and moderate troponins in “clean” coronaries), post-infarction aneurysm (persistent focal elevation), coronary spasm (vasospastic angina), hyperkalemia and severe conduction abnormalities, as well as “posterior” infarction (on standard ECG - ST depression in V1-V3 with high R). [12]

Risk factors

The factors associated with ischemic ST elevation are the same as those associated with coronary artery disease: age, smoking, diabetes, hypercholesterolemia, hypertension, and family history. The higher the overall risk, the higher the pre-test probability that ST elevation is a heart attack. Current guidelines recommend considering the risk immediately upon initial assessment. [13]

Pericarditis may be associated with viral infections, systemic inflammatory diseases, and postpericardiotomy syndrome. Brugada syndrome is a genetically determined channelopathic phenotype; the ECG pattern is enhanced by fever, drug provocation, and electrolyte shifts. [14]

Early repolarization is more common in young men and athletes; it usually proceeds favorably. However, "early repolarization syndrome" with an increased arrhythmogenic risk is extremely rare. Clinical evaluation (syncope, cardiac arrest) and exclusion of other causes are important. [15]

Takotsubo is more common in postmenopausal women after stress (emotional or physical). The ECG often resembles an acute myocardial infarction, so the strategy is the same: rapid coronary angiography to rule out occlusion. [16]

Pathogenesis

In coronary occlusion, a sharp transmural potential gradient occurs, which causes ST elevation in adjacent leads and reciprocal depression in opposite leads. As the infarction progresses, the ST segment may gradually decline, resulting in pathological Q waves. These early minutes are the "golden window" for reperfusion. [17]

Pericarditis causes inflammation of the epicardium and pericardium; injury currents are diffuse, so ST elevations are widespread and relatively "domed," often with PR depression as a marker of atrial surface inflammation. However, these signs are not completely specific. [18]

Benign early repolarization is associated with early termination of depolarization/early onset of repolarization and ion flow patterns in the subepicardium, which creates an elevated J-point and "high" ST in healthy individuals. This is an anatomical and electrophysiological variant of the norm. [19]

Brugada syndrome is caused by dispersion of depolarization/repolarization in the right outflow tract; the typical cow-shaped ST elevation in V1-V3 reflects the risk of malignant arrhythmias rather than coronary occlusion. Takotsubo, unlike MI, is associated with catecholamine stunning of the myocardium without persistent occlusion. [20]

Symptoms

Classically, STEMI presents with intense, crushing chest pain with radiating pain, cold sweat, weakness, and nausea; shortness of breath and fainting are also possible. However, in some patients (the elderly, women, and diabetics), symptoms may be atypical. If in doubt, proceed as if for a heart attack. [21]

Pericarditis is a stabbing/cutting pain that intensifies with inhalation and while lying down, and is relieved by sitting and leaning forward; often accompanied by subfebrile fever. There are no complaints with early repolarization; the finding is incidental. [22]

Brugada syndrome may not be accompanied by chest pain at all; syncope or a family history of sudden death are typical. Takotsubo is characterized by pain and shortness of breath "as in a heart attack," often following stress; troponins are moderately elevated, and coronaries are not critically occluded. [23]

A posterior infarction often causes back/interscapular pain, sometimes accompanied by inferior MI. A standard ECG shows ST depression in V1-V3 and high R waves; when recording V7-V9, there is ST elevation. [24]

Forms and stages

The causes are: ischemic (STEMI, vasospasm, posterior MI), inflammatory (pericarditis/myopericarditis), electrical/channelopathies (Brugada syndrome), benign (early repolarization), post-infarction (aneurysm), and "apparent" elevations in technical and conduction conditions. The strategies differ fundamentally. [25]

Based on the localization of ST elevation, the vessel is oriented toward: anterior wall (LAD), inferior (RCA/LCx), lateral (LCx/OM), posterobasal (posterolateral branches). Localization determines the risks (for example, proximal LAD - high risk). [26]

In terms of time, MI is classified into the hyperacute stage (high T waves, early ST elevation), acute (maximum ST↑), subacute (ST depression, appearance of Q/T inversion), and chronic (normalization/aneurysm with persistent ST↑). Knowledge of the dynamics helps in retrospective assessment. [27]

Separately, “masking” conditions are distinguished: left bundle branch block and cardiac pacing, where the original and modified Sgarbossa criteria are used to diagnose infarction. [28]

Table 1. The most common causes of ST elevation

Group	Examples/comments
Ischemic	STEMI, coronary spasm, posterior MI (V7-V9)
Inflammatory	Pericarditis/myopericarditis (diffuse ST↑, PR↓)
Benign	Early repolarization (J-point, no reciprocal)
Canalopathies	Brugada syndrome (V1-V3, saddle-shaped)
Others	Post-infarction aneurysm, takotsubo
Based on guidelines and clinical reviews.[29]

Complications and consequences

For STEMI, the key complications are fatal arrhythmias, cardiogenic shock, mechanical ruptures, and heart failure. Early reperfusion dramatically reduces the risk, so the goal of the system is to minimize the time to a guidewire/balloon or, if unavailable, to fibrinolysis. [30]

An error in differential diagnosis can lead to two extremes: missing an occlusion ("false negative") with severe outcomes, or a "false alarm" with unnecessary angiography/thrombolysis and the risk of bleeding. A balance is achieved by algorithms that first exclude MI and then confirm alternatives. [31]

Brugada syndrome carries the risk of sudden cardiac death due to polymorphic ventricular tachycardia/fibrillation. The treatment here is not coronary, but antiarrhythmic therapy/defibrillator implantation in selected patients. Takotsubo can be complicated by shock and LV thrombosis, but the coronaries are often intact. [32]

Pericarditis can lead to effusion and tamponade, while myopericarditis can lead to decreased LV function. However, it's important not to mistake pericarditis for MI, and vice versa; some of the symptoms overlap. [33]

Diagnostics

Basis: clinical findings + 12-lead ECG (repeat dynamically) + high-sensitivity troponins. Any suspicious clinical findings and ST elevation are treated as for STEMI, without waiting for all tests. Saturation, blood pressure, and signs of shock/pulmonary edema are assessed in parallel; if possible, bedside echocardiography is performed to assess regional contractility disorders. [34]

ECG clues in favor of MI: convex/horizontal ST elevation, reciprocal ST depression (except aVR/V1), STE in III > II with inferior MI, ST depression in V1-V3 (posterior MI), dynamics over minutes. Pericarditis/early repolarization is suggested by diffuse concave ST elevation, PR↓ (pericarditis), pattern stability, J notch (early repolarization). But first, exclude MI. [35]

In LBBB/ECS, modified Sgarbossa criteria are used (excessive discordance, proportionality of elevation/depression to QRS amplitude). In case of posterior MI, leads V7-V9 are recorded (an elevation of ≥0.5 mm is diagnostically significant). [36]

Next - coronary angiography (emergency for STEMI: primary PCI), for “non-ischemic” causes - echocardiography, CT coronary angiography/MR of the heart as indicated, provocative tests if spasm is suspected/Brugada - according to specialized protocols. [37]

Table 2. ECG signs in favor of STEMI vs. pericarditis/early repolarization

Sign	STEMI is more likely	Pericarditis/wound repolarization is more likely
ST form	Convex/horizontal	Concave "bowl"
Reciprocal ST depression	Common (except aVR/V1)	Usually no (except aVR/V1)
PR segment	It might be normal	Often PR↓ (pericarditis)
STE in III > II (lower holes)	Supports the inferior wall of the myocardium	Not typical
J-spot with a notch	Not typical	Supports early repolarization
From clinical reviews and educational resources. [38]

Table 3. ST elevation "special cases" and tips

Situation	What to look for	What to do
LBBB/EX	Modified Sgarbossa criteria	Consider OMI; low threshold for PCI
"Rear" IM	ST↓ in V1-V3, high R; V7-V9: ST↑ ≥0.5 mm	Place V7-V9; proceed as for MI
Brugada	V1-V3: saddle-shaped/cow-shaped ST↑	Eliminate medications/fever; arrhythmia tactics
Takotsubo	STE/T inversion + moderate troponins, "clean" coronaries	Support, eliminate occlusion
Based on LITFL, StatPearls, reviews. [39]

Table 4. Sgarbossa criteria (modified) for LBBB/EKS (briefly)

Criterion	Comment
Consensus ST elevation ≥1 mm in ≥1 lead	High specificity
Consensus ST depression ≥1 mm in V1-V3	Supports posterior wall infarction
Discordant ST elevation exceeding the proportional threshold	"Excessive discordance" (Smith-modified)
Resource on criteria and their modifications. [40]

Differential diagnosis

The step-by-step logic is as follows: (1) treat as STEMI if clinical presentation and ECG are consistent, without wasting time; (2) simultaneously search for signs of alternatives (PR↓, "diffuseness," J-notch, Brugada pattern); (3) in complex cases - bedside echo, additional leads, consultation with the catlab team. This algorithm reduces both missed readings and "false alarms." [41]

Pericarditis vs. STEMI: neither symptom is absolute. Even PR↓ occurs in some infarctions. Therefore, when in doubt, the priority is to exclude coronary occlusion. Reciprocal changes, the location of the STE, and clinical symptoms are helpful. [42]

Early repolarization is usually stable and "young": no dynamics, J notching, diffuse concave ST↑ without symptoms. However, in a patient with chest pain and risk factors, we do not rely on "benignity" until we rule out MI. [43]

Brugada and takotsubo are “other worlds”: there is no coronary occlusion, but the risks (arrhythmia, shock) are also serious, so their diagnosis and management require specialized protocols. [44]

Table 5. Common STEMI mimics and the key to distinguishing them

Simulator	What helps to distinguish
Pericarditis	Diffuse ST↑, PR↓, position-dependent pain
Early repolarization	Young age, J-notch, stability
Brugada syndrome	V1-V3 typical pattern, triggers (fever)
Post-infarction aneurysm	Persistent local ST↑, Q-waves, "old" history
"Rear" IM	On a standard ECG - ST↓ V1-V3; V7-V9 - ST↑
Based on clinical guidelines/reviews.[45]

Treatment

STEMI: reperfusion strategy. The method of choice is primary PCI. The time goals in current guidelines are: from first medical contact to the "first device" (guidewire/balloon) no more than ≈90 min; if this is unachievable, consider immediate fibrinolysis followed by early invasive tactics ("pharmacoinvasive strategy"). Precise thresholds are determined by local networks, but the principle is the same: minimize ischemic time. [46]

Concomitant therapy for STEMI. Antiplatelet (aspirin + potent P2Y12 inhibitor), anticoagulation, oxygen as indicated, nitrates/beta-blockers unless contraindicated, calcium antagonists (not routinely), pain relief and treatment of complications. After reperfusion, secondary prevention: high-intensity statins, ACE inhibitor/ARB, beta-blocker, risk factor management. [47]

Pericarditis/myopericarditis. Nonsteroidal anti-inflammatory drugs + colchicine, limiting exercise; in case of myopericarditis, close observation, sometimes hospitalization and ruling out ischemia/coronary artery disease. Glucocorticoids are reserved. Thrombolysis and PCI are not indicated in this case. [48]

Brugada/takotsubo. In the presence of Brugada pattern and syncope, assess the risk of sudden death, discuss implantation of a cardioverter-defibrillator; avoid triggers and contraindicated medications. In the case of takotsubo, supportive therapy, anticoagulation as indicated (LV thrombus), and rule out coronary occlusion by angiography. [49]

Table 6. Reperfusion time goals (landmarks)

Stage	Target
First medical contact → "first device" (PPCI)	≤90 minutes, faster if possible
If PPCI is not achievable in a timely manner	Immediate fibrinolysis → early invasive strategy
Door→needle (fibrinolysis)	~30 minutes
After fibrinolysis with persistent ischemia	Emergency "patch" PCI
According to ESC 2023 and ACC/AHA 2025. [50]

Table 7. Contraindications to fibrinolysis (abbreviated)

Absolute	Relative
Any previous intracranial hemorrhage; known intracranial tumor/AVM; stroke <3 months (excluding acute ischemic <4.5 hours in special protocols); suspected aortic dissection; active bleeding	Uncontrolled hypertension, recent surgery/trauma, pregnancy/postpartum period, etc.
The list is specified by local protocols according to the guidelines. [51]

Table 8. Tactics for “posterior” MI

Step	Detail
Suspicion	ST↓ in V1-V3 + high R/T; often with inferior MI
Confirmation	Registration of V7-V9 (ST↑ ≥0.5 mm is sufficient)
Action	Reperfusion tactics as in STEMI
Note	Film flipping is a gimmick, but better than V7-V9
Educational sources and reviews. [52]

Table 9. Early repolarization: markers of “benignity”

Sign	Explanation
Young age, athlete	Common phenotype
J-wave/notch	At the QRS-ST border
Concave ST shape, no reciprocals	Distinguishes from IM
Pattern stability over time	There is no dynamics from minutes to hours
According to reviews by Circulation and LITFL. [53]

Prevention

Prevention of STEMI involves preventing atherosclerosis: smoking cessation, lipid management (statins/ezetimibe/PCSK9 inhibitors according to risk), blood pressure and sugar control, exercise, and diet. Information campaigns such as "call an ambulance if you have chest pain" reduce the delay to reperfusion—this is part of primary and secondary prevention at the population level. [54]

For "non-ischemic" ST elevations, prevention is specific: for Brugada - avoidance of provoking drugs/fever, family screening; for pericarditis - treatment of infection and anti-inflammatory therapy; for vasospasm - smoking cessation, calcium antagonists; for early repolarization - usually no measures are required. [55]

Forecast

The prognosis for STEMI is determined by the rate of reperfusion and the size of the lesion: the faster blood flow is restored, the higher the chances of survival and preservation of left ventricular function. Modern reperfusion networks and standardized time goals reduce mortality and disability. [56]

In "non-ischemic" ST elevations, the prognosis varies greatly: early repolarization is usually favorable; pericarditis is often benign with proper therapy; Brugada syndrome carries a risk of sudden death and requires specialized monitoring; takotsubo is usually reversible, but severe complications are possible in the acute period. [57]

FAQ

• Does ST elevation always mean a heart attack?

No. It's a "red flag," but the causes vary. Coronary occlusion is ruled out first, followed by pericarditis, early repolarization, Brugada, takotsubo, and others. The "rule out MI first" algorithm saves lives. [58]

• What is the treatment time for suspected ST-elevation MI?

The goal is primary PCI within ≈90 minutes of first medical contact; if this is not achievable, immediate fibrinolysis with early invasive management is indicated. "Perfect" tests are not expected if the ECG/clinical findings are typical. [59]

• How to distinguish pericarditis from a heart attack using an ECG?

Pericarditis most often produces diffuse concave ST elevation with PR depression; in infarction, the elevations are localized, the shape is convex/horizontal, and there are reciprocal depressions. However, ruling out infarction is always the first step. [60]

• What are the Sgarbossa criteria and when are they needed?

This is a set of ECG features for diagnosing infarction during left bundle branch block/pacing. A modified version uses "proportional" ST discordant thresholds. These are needed when standard criteria are not applicable. [61]

• Why place leads V7-V9?

To "see" posterobasal infarction: on a standard ECG it often appears as ST depression in V1-V3; additional leads confirm ST elevation and accelerate reperfusion. [62]