ECG “S1–S2–S3” Pattern
The term “S1–S2–S3 pattern” is not a standard ECG label with universally accepted criteria for the 12-lead ECG. [1] In practice, “S1–S2–S3” most commonly refers to a constellation of right-sided cardiac depolarization features associated with right ventricular dysfunction/pulmonary heart disease. [1]
Heart Sounds S1, S2, S3 vs ECG Terminology
S1, S2, and S3 are also widely used to denote heart sounds that occur during the cardiac cycle. [2] On ECG tracings, S1–S3 is therefore not an inherent temporal marker of the waveform; ECG interpretation uses QRS morphology, axis, and lead-specific R/S relationships rather than “S1–S2–S3” as time-labeled events. [2]
Existence of an “S1–S2–S3” Pattern on a Standard 12-Lead ECG
A descriptive “S1–S2–S3” pattern can be identified on a standard 12-lead ECG using a specific convention that focuses on prominent S-wave presence in multiple limb leads. [1] Device-based and teaching resources that use this term define it operationally as prominent S waves in leads I, II, and III. [3]
Operational Definition Used in ECG Teaching/Algorithms
In the commonly used convention, the “S1–S2–S3 pattern” is characterized by prominent S waves in leads I, II, and III. [3] This ECG pattern is typically discussed alongside other right ventricular and pulmonary hypertension markers rather than as a stand-alone diagnostic criterion. [1]
Clinical Representation
“S1–S2–S3,” when applied in the right-sided ECG context, represents right ventricular dysfunction with pulmonary hypertension in the setting of additional supportive criteria. [1] Diagnostic performance reported in a review article indicates high specificity when used with the full set of criteria, with sensitivity reported as <50% and specificity as >95% for right ventricular dysfunction/pulmonary hypertension. [1]
Key Associated ECG Features Used With the Pattern
Right ventricular dysfunction/pulmonary hypertension assessment using an “S1–S2–S3”-type constellation is described together with a pattern of right-dominant forces, including features such as right-sided predominance in precordial leads and related right-sided enlargement markers. [1] The “S1–S2–S3” label functions as one component of this broader ECG constellation rather than capturing all required information by itself. [1]
Interpretation Caveats
The presence of the “S1–S2–S3” descriptor alone does not establish a diagnosis because the diagnostic sensitivity is reported to be <50% even when using the broader ECG constellation. [1] The term is convention-dependent, so equivalently named patterns may vary across sources and ECG interpretation systems. [1]
Practical Meaning for Clinical Use
When encountered as “S1–S2–S3” in ECG interpretation materials, it indicates a pattern consistent with right ventricular dysfunction/pulmonary hypertension only in conjunction with other supporting ECG findings and the clinical context. [1] Otherwise, the term should be treated as a naming convention for a particular depolarization morphology pattern rather than a universally standardized 12-lead ECG rule. [1]
References
- S1–S2–S3 is also used for heart sounds, which are conceptually distinct from ECG waveform labeling. [2]
- In ECG-focused usage, the “S1–S2–S3” descriptor is operationally tied to prominent S waves in leads I, II, and III and is used within a larger right ventricular dysfunction/pulmonary hypertension ECG constellation. [1] [3]