Arrhythmias Associated with Aortic Stenosis
Aortic stenosis is primarily associated with ventricular arrhythmias (including ventricular tachycardia and ventricular fibrillation) and conduction disturbances in the His bundle and trifascicular system, particularly when the valve is calcified, with atrial fibrillation also being a common comorbidity that worsens prognosis.
Ventricular Arrhythmias
Primary Arrhythmic Manifestations
Ventricular tachycardia and ventricular fibrillation are the predominant life-threatening arrhythmias in aortic stenosis, with Holter monitoring demonstrating ventricular tachyarrhythmias in 6 of 7 patients who died suddenly (86%), while only 1 patient (14%) had bradyarrhythmia 1.
Premature ventricular contractions (PVCs) are highly prevalent, occurring in 83.5% of patients with moderate to severe aortic stenosis before intervention, with complex PVCs (multifocal, couplets, or ventricular tachycardia) present in 48.6% of patients 2.
The frequency and severity of ventricular arrhythmias decrease significantly after transcatheter aortic valve implantation (TAVI), with complex arrhythmias reducing from 48.6% pre-procedure to 16.4% at 12 months post-procedure 1, 2.
Mechanisms of Ventricular Arrhythmias
High blood pressure is not arrhythmogenic per se, but ventricular overload from aortic stenosis creates the substrate for arrhythmias, even when peripheral blood pressure is low 1.
Multiple mechanisms contribute to sudden cardiac death in aortic stenosis: abnormal Betzold-Jarisch reflex, ventricular tachyarrhythmias, and atrioventricular conduction disturbances 1.
Increased Tp-e interval and Tp-e/QTc ratio correlate with AS severity and serve as independent predictors of severe aortic stenosis, indicating increased ventricular repolarization dispersion and arrhythmia risk 3.
Conduction System Abnormalities
Conduction disorders in the His bundle and trifascicular system are associated with aortic stenosis, with more extensive involvement when the valve is calcified 1.
These conduction abnormalities can lead to bradyarrhythmias, though this is a less common mechanism of sudden death compared to ventricular tachyarrhythmias 1.
Atrial Fibrillation
Prevalence and Impact
Atrial fibrillation occurs in 26.2% of patients with moderate to severe aortic stenosis and significantly worsens prognosis 4.
Mortality is substantially higher in AS patients with AF compared to those in sinus rhythm (46% vs. 36.2%, HR 1.424,95% CI 1.121-1.809, p = 0.004) 4.
The mortality risk from AF is greater in severe AS (HR 1.644) than in moderate AS (HR 1.376), demonstrating significant interaction between AF and AS severity 4.
Clinical Implications of AF
Atrial fibrillation has adverse effects on atrial pump function and ventricular rate in aortic stenosis, and prompt cardioversion or pharmacological rate control is essential if cardioversion is unsuccessful 1.
In patients with AF and aortic stenosis, aortic valve replacement provides survival benefit (HR 0.365,95% CI 0.202-0.627, p < 0.001), though the protective effect is slightly less than in patients with sinus rhythm 4.
When corrected for echocardiographic variables strongly correlated with AF, AF itself may not be independently associated with mortality, suggesting the worse prognosis reflects underlying cardiac damage rather than the arrhythmia alone 4.
Risk Stratification
Symptomatic vs. Asymptomatic Patients
Sudden cardiac death risk is low (3-5%) in asymptomatic patients with aortic stenosis, and prospective data show no sudden deaths occurred in 123 asymptomatic patients followed for 2.5 years 1.
Once symptoms develop, the incidence of sudden cardiac death increases dramatically to 8-34% in different studies, with approximately 20% of all deaths in AS being sudden 1.
Predictive Factors
History of syncope, previous cardiac arrest, and rapid sustained ventricular tachycardia on Holter monitoring or exercise testing are regarded as predictors of major arrhythmic events 1.
Left ventricular mass and Tp-e/QTc ratio are independent predictors of severe aortic stenosis and associated arrhythmia risk 3.
Management Implications
Monitoring and Intervention
Restriction of physical activity should be advised in patients with moderate and especially severe aortic stenosis to reduce arrhythmia risk 1.
Patients presenting with sustained ventricular tachycardia or fibrillation should be considered for ICD implantation, particularly if inducible at electrophysiological study 1.
Beta blockers may be appropriate for patients with aortic stenosis who have reduced ejection fraction, prior MI, arrhythmias, or angina pectoris 1.
Post-Intervention Outcomes
Ventricular arrhythmia burden decreases significantly within the first month after TAVI, with further reduction at 12 months, related to improvements in left ventricular function 2.
A case report demonstrates that recurrent ventricular tachycardia from severe AS can be reversible after percutaneous aortic balloon valvuloplasty and TAVI 5.