What to do in case of heart rhythm disorders?

In theory, all types of arrhythmias can occur in heart failure patients. If a cardiac arrhythmia is suspected, an ECG should always be taken to document the underlying heart rhythm and to make a correct diagnosis.

The most frequent cardiac arrhythmias in patients with heart failure are:

1. Atrial fibrillation (AF) and atrial flutter

Atrial fibrillation is very common in heart failure (both HFrEF and HFpEF) and is normally not immediately life-threatening. Frequently, atrial fibrillation is a trigger for heart failure decompensation. Asymptomatic tachycardia due to AF can also cause heart failure with reduced LVEF over the course of weeks (tachycardia cardiomyopathy). After restoration of the normal rhythm, normally the left ventricle ejection fraction will recover over the course of months. In addition, it is also a frequent cause of thromboembolic complications (ischemic stroke, other peripheral embolism such as an acute cold leg, renal infarction, spleen infarction, etc.).

Timely detection and documentation of atrial fibrillation are very important to prevent cardiac decompensation and thromboembolic complications. During every clinical check-up, the heart rhythm must therefore be checked to determine whether it is regular or not, especially if the patient is not known to have persistent or permanent atrial fibrillation. If in doubt, an ECG should be taken.

Symptoms

Palpitations.
Increased dyspnea on exertion.
Cardiac decompensation.
Angina due to tachycardia.
Due to embolism: CVA, renal infarction, acute cold leg,...

Differential diagnosis of an irregular rhythm

Atrial fibrillation or frequent extrasystoles (atrial or ventricular)?

With extrasystoles there is a regular rhythm with occasional irregularities in the rhythm due to the extrasystoles. Due to very frequent extrasystoles (bigeminy, trigeminy, quadrigeminy), the distinction from AF can sometimes be clinically very difficult.
In atrial fibrillation there is a continuous irregular heart rhythm with no P waves for the QRS complex on the ECG.

To diagnose atrial fibrillation and to distinguish it from extrasystoles, an ECG must always be taken.

Atrial fibrillation with a quiet ventricular response. There are no P waves, but atrial fibrillation waves and a continuous irregular ventricular rhythm.

Atrial fibrillation with rapid ventricular response. Left axis and left anterior hemiblock.

Atrial flutter with a typical sawtooth pattern in leads II, III and aVF atrial. Right bundle branch block.

Management

With atrial fibrillation the following things must happen:

2. Bradycardia

Bradycardia is an excessively slow heart rate < 60 per minute. This is common in patients with heart failure. This is often facilitated by the use of beta blockers, digoxin, ivabradine or amiodarone.

Bradycardia can result from:

Sinus bradycardia (sick sinus syndrome).
A high-grade, second or third degree AV block.
Atrial fibrillation with a slow ventricular response.

To make the distinction, it is always best to take an ECG.

Sinus bradycardia at 34 per minute.

Sinus rhythm with a long first degree AV block (PR interval 380-400 ms) and a left bundle branch block. Each P wave is still followed by a QRS complex.

Sinusal rhythm with second degree AV block with 2 on 1 block (a P wave is alternately followed or not by a QRS complex).

Sinus rhythm with third degree AV block. P waves are not followed by a QRS complex. There is AV dissociation with a slow ventricular escape rate of 33 per minute with right bundle branch block morphology.

Management

In case of symptomatic bradycardia with malaise, presyncope or syncope, the patient should be hospitalized immediately for monitoring and further management.

An asymptomatic sinus bradycardia or AF with slow ventricular response at 50-60/min can be accepted.

With a resting heart rate < 50/min, the bradycardic medication should be reduced:

Preferably and if applicable, digoxin or ivabradine should first be reduced or stopped.
Whether or not to continue amiodarone should be decided by the treating cardiologist.
Beta blockers can be reduced in dose if taken at a high dose or target dose.
- With HFpEF these can also be stopped.
- With HFrEF and HFmrEF it is best to continue beta blockers and opt for a pacemaker implant sooner.

The indications for the implantation of a pacemaker are the same as in normal patients. When a high degree of ventricular pacing is expected (e.g. AV block or atrial fibrillation with slow response), resynchronization pacing (CRT) or conduction pacing (left bundle branch pacing) should be chosen at implant, given the classic apical pacing in the right ventricle pacing often results in further deterioration of left ventricular function through further induction of dyssynchrony in the left ventricle.

Also read: Therapy with implantable devices ICD, CRT, LBBA Pacing

3. Ventricular tachycardia (VT) and ventricular fibrillation (VF)

These ventricular arrhythmias are usually life-threatening and are always an indication for hospital admission (unless the patient has an ICD and only felt one shock and is symptom-free again (see points of interest for devices).

Symptoms

Collapse and sudden death (if resuscitation is not started quickly) (VF or VT with rapid rhythm with disappearance of cardiac output).
Hypotension and cardiogenic shock (VT with rapid rhythm with significant decrease in cardiac output).
Palpitations and malaise (if a slower VT while maintaining cardiac output).
Cardiac decompensation (if a slower VT while maintaining cardiac output).

ECG

VT: wide QRS tachycardia, monomorphic or multimorphic.
VF: smaller fibrillation waves, no longer distinguishable QRS complex.

Possible causes or triggering factors

Myocardial ischemia (acute coronary syndrome or coronary stenosis).
Poor heart function or a cardiomyopathy.
Myocardial scar tissue (due to a myocardial infarction, myocarditis, sarcoidosis, etc.).
Ionic disorders (especially hypo- or hyperkalemia).
Hyperthyroidism.
Polypharmacy (QTc prolonging medications, digoxin,…).
Drugs (cocaine, amphetamines).