Couplets I49.3

Couplets are two consecutive extrasystoles: normal beat - extra beat - extra beat = N - E - E (Herold 2022). Hall (2008) et al. describe couplets of ventricular or supraventricular origin, other authors such as (Klinge 2015) write exclusively about couplets of ventricular origin.

Couplets are differentiated between:

• Monotopic couplets

These start from the same origin and show up in the ECG as identical extrasystoles. Therefore they are also called "twins".

• Polytopenic Couplets

Polytopic Couplets have a different origin, show up in the ECG as differently deformed extrasystoles and are also called "siblings". Polytopic couplets are generally considered to be more dangerous (Freytag 2010).

• Ventricular Couplets:

These are included in the group of ventricular ectopy along with other arrhythmias such as bigeminal, trigeminal,and triplets (Moon 2020).

Couplets can be precursors of dangerous ventricular tachyarrhythmias up to ventricular fibrillation in organically heart diseased patients (Herold 2022).

In the classification according to Lown (see VES), couplets belong to complex VES grade IV a (Herold 2022). Nowadays, however, the Lown classification is hardly used anymore (Braun 2022)

• Supraventricular Couplets:

SVES- couplets, together with volleys (Stierle 2020), belong to the group of complex SVES (Hall 2008). They may be precursors of atrial fibrillation (Stierle 2020).

Couplets occur more frequently with increasing age (Platt 2013).

The causes of the couplets correspond to those of the extrasystoles, which are:

- Idiopathic (Ip 2017)

- Physiological causes:

These are also found in healthy individuals. Here, extrasystoles occur due to increased sympathetic tone (Kasper 2015), emotional arousal, autonomic lability, overtiredness, ingestion of stimulants such as alcohol, nicotine, caffeine, increased vagotone, etc (Herold 2022).

- Organic diseases of the heart:

These include cardiomyopathies, myocarditis, coronary artery disease (Herold 2022), cardiac tumors, congenital heart defects (Paul 2018).

- Extracardiac Causes:

Extracardiac causes include hyperthyroidism, hypokalemia, use of certain medications such as. Antiarrhythmics, sympathomimetics, digitalis, tricyclic antidepressants (Herold 2022), catecholamines, quinidine, atropine, antiarrhythmics (Wolff 2012), fever, infections (van Aken 2007), acidosis, hypoxia, electrolyte disturbances, especially hypokalemia, hypercalcemia, hypomagnesemia (Haas 2021).

Pathophysiologically, ventricular and supraventricular couplets result from increased or abnormal automaticity, triggered activity, or reentry, respectively (Fölsch 2013).

Couplets can cause the symptoms known from extrasystoles. These include:

- Palpitations (Herold 2022)

- Feeling of weakness

- Dizziness (Braun 2022)

- Cardiac syncope / presyncope (Kasper 2015).

- Dyspnea (Meismann 2021).

Since extrasystoles cause an unconscious reaction of the autonomic nervous system, palpitations can trigger an anxiety reaction up to a panic attack in affected persons. These patients may complain of dyspnea, chest tightness, etc. (Meismann 2021).

Ventricular couplets can trigger, for example:

- ventricular tachycardia

- ventricular fibrillation (Khalil 2019)

- AV nodal reentry tachycardia (Hoang 2016).

Supraventricular couplets can trigger, for example:

- AV nodal reentry tachycardia

- supraventricular tachycardia (Carbone 2016)

- paroxysmal atrial fibrillation (Hall 2008)

If couplets occur only occasionally, no therapy is usually required. Only if they are numerous and especially if the minute volume (stroke volume x number of heartbeats per minute [Buchsteiner 2020]) decreases, treatment with antiarrhythmic drugs may be necessary (Freytag 2010).

S. a. Extrasystoles

General information

On ECG, couplets are recognizable by:

- 1. two consecutive VES with the typical deformation and widening of the ventricular complex to > 110 ms, compensatory pauses and discordant QRS- and T-wave axes (Moon 2020).

- 2. two consecutive SVES (Hall 2008) with the QRS- complex appearing normal in shape and width (in most cases) typical of SVES (Block 2006) and a QRS- duration of < 120 ms (Kasper 2015), the prematurely incident and abnormally configured P- waves (Stierle 2020), changes in PQ- time, and the absence of compensatory pauses (Block 2006).

The occurrence of couplets during the exercise ECGrepresents a relative criterion for termination (Herold 2022).

If, after a myocardial infarction, couplets, among others, occur repeatedly, this is a sign of deteriorating ventricular function and increased mortality. Routine antiarrhythmic treatment is not recommended. Therapy with the sodium channel blocker flecainide actually increases mortality. Amiodarone may reduce the risk of sudden cardiac death, but it does not improve all-cause mortality (Kasper 2015).

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