It was in 1903 when the bipolar three-channel electrocardiogram (ECG) was invented and recorded by William Einthoven. Since then, ECG has been a tool of remarkable clinical power, as it can quickly provide physicians with helpful and even critical information. As ECG communicates in its own unique way, it is of paramount importance for healthcare professionals to have the necessary competency to interpret it. Thanks to some investigators having an acute eye for detail, rare cardiological syndromes have been identified and characterized by their specific ECG patterns, which may testify to their clinical presentation. The instant identification of these patterns may lead to the immediate and proper management and treatment of those patients with favorable morbidity and mortality outcomes. This review focuses on the detection of less common cardiological clinical syndromes, highlighting the general context and the ECG findings. A summary table of the syndromes’ diagnostic criteria and ECG patterns is provided below (Table 1), in order to offer a short overview of the main points and render the information more accessible to the reader.

ECG Syndrome	ECG Diagnostic Criteria	ECG Aspect
Wellen’s syndrome	– Normal ECG in angina, T wave changes in V2-3 when pain-free. – Absence of pathological Q waves. – No R wave loss.
De Winter syndrome	– No ST-segment elevation in precordial leads. – Up-sloping ST-segment depression at J-point >1 mm. – Deep symmetrical T waves in precordial leads. – ST-segment elevation in aVR <0.5 mm. – May be preceded or followed by ST-segment elevation.
Kounis syndrome	– Evidence of myocardial ischemia on ECG in presence of systemic allergic reaction.
Takotsubo syndrome	– New and reversible ECG changes (ST-segment elevation, ST-segment depression, left bundle branch block, T-wave inversion, and/or QTc prolongation) during the acute phase (3 months).
Yamaguchi syndrome	– Giant negative T waves (>10 mm), left ventricular hypertrophy and possibly signs of complications, including atrial fibrillation and ACS with ST-segment elevation.
Wolff–Parkinson–White syndrome	– Short PR interval <120 ms. – Slurred upstroke at QRS beginning, called delta wave. – Wide QRS complex >120 ms. – T wave, ST-segment changes.
Lown–Ganong–Levine syndrome	– Short PR interval <120 ms. – Normal QRS complex <120 ms. – Absence of delta wave.
Brugada syndrome	– Type 1 consists of coved ST-segment elevations greater than 2 mm followed by an inverted T wave. – Type 2 consists of a saddle-back ST-segment elevation greater than 2 mm followed by a normal or biphasic T wave. – Type 3 is characterized by a coved or saddleback-shaped ST-segment elevation that is equal or less than 1 mm.
Frederick’s syndrome	– Atrial fibrillation “f waves” or atrial flutter waves. – Third degree AV block.
PAFIYAMA syndrome	– Onset as paroxysmal atrial fibrillation. – ST-segment elevation at J-point >0.1 mm in 2 leads. – Inverted T waves in 2 leads. – Left atrial enlargement signs. – Left ventricular hypertrophy signs.
Haïssaguerre syndrome	– J-point elevation >1 mm in >2 contiguous inferior and/or lateral leads in a patient with history of resuscitation from otherwise unexplained ventricular fibrillation or polymorphic ventricular tachycardia. Presence of J-point elevation >1 mm in >2 contiguous inferior and/or lateral leads on ECG.
Osborn syndrome	– Haïssaguerre and Brugada syndrome criteria may be used.
LEOPARD syndrome	– Left or biventricular hypertrophy. – Repolarization abnormalities. – Prolonged QT-interval. – Atrioventricular blocks.

Wellen’s Syndrome

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T wave inversion or biphasic T wave due to ischemia.

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T wave inversion, in most leads, due to Takotsubo cardiomyopathy.

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ST-segment depression and T wave flattening, best seen in V2–V4, due to hypokalemia.

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T wave inversion in V1–V6 due to acute pulmonary embolism.

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T wave inversion due to cardiac memory, such as in LBBB, pacemakers, or transient tachycardia.

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T wave inversion in V1–V3 physiologically in prepubertal patients.

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T wave inversion in most leads due to pericarditis, myocarditis, or advanced AV block [10].

De Winter syndrome;

Kounis syndrome;

Takotsubo (Broken Heart) syndrome;

Yamaguchi syndrome;

WPW syndrome;

LGL syndrome;

Brugada syndrome;

PAFIYAMA syndrome;

Haissaguerre syndrome;

Osborn syndrome;

Conclusions