Low Deceleration Capacity is Associated with Higher Stroke Risk in Patients with Paroxysmal Atrial Fibrillation
Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an increased risk of ischemic stroke, heart failure, and mortality. Stroke risk assessment in AF patients is currently based on CHADS2 and CHA2DS2-VASc scores, which include major risk factors such as age, diabetes, heart failure, previous stroke/transient ischemic attack (TIA), and hypertension. AF is a complex arrhythmia with multiple mechanisms, including electrical remodeling, structural remodeling, and autonomic neural dysregulation. The cardiac autonomic nervous system (CANS) plays a crucial role in the initiation and maintenance of AF, with fluctuations in CANS activity often preceding the onset of paroxysmal AF.
Deceleration capacity (DC) is a non-invasive electrocardiographic index that quantitatively measures cardiac autonomic nervous tension. Introduced in 2006, DC has proven to be a superior indicator compared to traditional heart rate variability for assessing cardiac autonomic function. DC is particularly effective in predicting post-myocardial infarction sudden death and has been used to assess the effects of pulmonary vein ablation on cardiac autonomic function in paroxysmal AF patients. A preserved DC (greater than 4.5 ms) indicates a low risk of mortality, while a poor DC (less than or equal to 2.5 ms) suggests a higher mortality risk.
This study aimed to explore the influencing factors of abnormal DC and the relationships between DC and stroke risk in patients with paroxysmal AF. The study included 259 hospitalized paroxysmal AF patients with DC measurements derived from 24-hour Holter electrocardiography recordings taken between August 2015 and June 2016. Multivariable regression analysis was performed to evaluate the associations between correlated variables and abnormal DC values. The relationship between DC and ischemic stroke risk scores in patients with paroxysmal AF was also analyzed.
The study population consisted of 259 hospitalized patients with paroxysmal AF, of whom 143 (55.2%) were male, with a mean age of 66.4 years. Among these patients, 38 showed abnormal DC values. Univariate analysis revealed that age, hypertension, heart failure, and previous stroke/TIA were significantly associated with abnormal DC values. Multivariable logistic regression analysis identified a history of previous stroke/TIA as independently associated with abnormal DC values in patients with paroxysmal AF, with an odds ratio of 2.861.
Patients with abnormal DC values exhibited higher stroke risk scores, as measured by both CHADS2 and CHA2DS2-VASc scores. The mean CHADS2 score was significantly higher in the abnormal DC group (2.25) compared to the normal DC group (1.40). Similarly, the mean CHA2DS2-VASc score was higher in the abnormal DC group (3.76) than in the normal DC group (2.71). Correlation analysis demonstrated that DC was negatively correlated with both CHADS2 and CHA2DS2-VASc scores, indicating that lower DC values are associated with higher stroke risk.
The findings suggest that lower DC is closely associated with previous stroke/TIA and is negatively correlated with higher stroke risk scores in patients with paroxysmal AF. This indicates that DC could serve as a potential indicator of stroke risk in this patient population. The study highlights the importance of cardiac autonomic dysfunction in the pathophysiology of AF and its implications for stroke risk assessment.
Several factors contribute to the observed associations between DC and stroke risk. Older age, hypertension, heart failure, and previous stroke/TIA are well-established risk factors for stroke in AF patients. These conditions are also associated with abnormalities in cardiac autonomic function, which are reflected in DC values. The study found that patients with abnormal DC values were older and had a higher prevalence of hypertension, heart failure, and previous stroke/TIA compared to those with normal DC values.
The role of the autonomic nervous system in AF and stroke risk is complex. Increased CANS activity can lead to arterial stiffness and increased vascular resistance, which may contribute to hemodynamic changes and cerebral infarction. The study’s findings are consistent with previous research showing that DC is decreased in patients with hemispheric infarction and correlates with the severity of stroke.
The study has several limitations. Its retrospective design and single-center data collection may introduce bias. Additionally, the study only collected data on medication use during hospitalization, which may not fully capture the impact of long-term drug therapy on DC values. Future research should consider multi-center, prospective studies with larger sample sizes to validate these findings and explore the predictive value of DC for stroke risk in paroxysmal AF patients.
In conclusion, abnormal DC is independently associated with previous stroke/TIA in patients with paroxysmal AF and is negatively correlated with higher stroke risk scores. These findings suggest that DC could be a valuable marker for assessing stroke risk in this patient population, potentially improving risk stratification and guiding clinical decision-making.
doi.org/10.1097/CM9.0000000000000391
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