Atrial Fibrillation Symptom Perception

Abstract

Atrial fibrillation (AF), the most common cardiac arrhythmia, is associated with a significantly increased risk of ischemic stroke, heart failure, and death. AF is a heterogenous disease both in terms of the pathophysiologic mechanisms that lead to the disease, and in terms of symptom presentation. Although most patients with AF perceive symptoms, their symptom experience is highly variable. The purpose of this paper is to review the: 1) epidemiology and pathophysiology of AF, 2) symptoms associated with AF, and 3) implications for clinical practice based on disparate symptom perception.

Introduction

Atrial fibrillation (AF), the most common cardiac arrhythmia, is defined as uncoordinated atrial activation with consequent ineffective atrial contraction.¹ Electrocardiographic (ECG) characteristics of AF are considered “irregularly irregular” and include irregular R to R intervals (if atrioventricular conduction remains intact), the absence of distinct P-waves, and irregular atrial activity.¹ AF is associated with nearly a 5-fold increased risk of stroke and heart failure and greater than 1.5-fold increased risk of mortality.^2-4 Compared to men, women have a 12% greater risk of mortality.² In addition to reducing AF-related morbidity and mortality, a major goal of AF treatment is to reduce the symptom burden.^1,5 Although most patients with AF perceive symptoms, the symptom experience is highly variable, with some individuals reporting no symptoms and others reporting severe symptoms that negatively impact functional status and quality of life.^5,6 The purpose of this paper is to review the: 1) epidemiology and pathophysiology of AF, 2) symptoms associated with AF, and 3) implications for clinical practice based on disparate symptom perception.

Epidemiology and Classification of Atrial Fibrillation

AF currently affects more than 5 million individuals in the United States and the prevalence is projected to reach 12.1 million by 2030.⁷ AF is increasingly common with advancing age, effecting approximately 8% of adults over age 65 and more than 14% of adults age 85 or older.⁸ In addition to advanced age, several comorbid conditions and lifestyle factors increase the risk of developing AF including hypertension, coronary artery disease, heart failure, valvular heart disease, diabetes mellitus, obesity, hyperlipidemia, sleep apnea, hyperthyroidism, moderate to heavy alcohol consumption, and smoking.^1,3,9

AF is classified in terms of the duration of arrhythmia episodes and the pattern of episode termination. Paroxysmal AF is defined as AF that terminates within 7 days of onset, either spontaneously or with intervention. Persistent AF is defined as AF that is sustained for over 7 days, typically requiring medical or procedural intervention to restore sinus rhythm. Longstanding persistent AF is defined as continuous AF lasting for more than 12 months. Permanent AF is when the patient and clinician decide jointly to cease attempts to restore sinus rhythm.^1,9 Additional classifications based on the cause of the arrhythmia include vagally-mediated AF (AF precipitated by a period of high parasympathetic tone, such as sleep), post-operative AF (typically related to major cardiac surgery), and valvular AF (AF associated with valve replacement, mitral stenosis, or mitral repair).^1,9

Classifying an individual’s risk status for thromboembolic ischemic stroke is essential to guide selection of an appropriate antithrombotic treatment strategy in patients with AF. Clinicians often calculate the CHA2DS2-VASc¹⁰ score to quantify the risk of thromboembolism. CHA2DS2-VASc is calculated based on an individual’s history of heart failure (C), hypertension (H), age ≥ 65 years (A), diabetes (D), stroke/transient ischemic attack (S), and vascular disease (VASc), with 1 point assigned per risk factor, but 2 points for history of ischemic stroke/transient ischemic attack and 2 points for age if the patient is ≥ 75 years old: the higher the score, the greater the risk of ischemic stroke.

Pathophysiology of Atrial Fibrillation

AF is the result of diverse pathophysiologic (genetic, structural, and electrophysiologic) mechanistic pathways, with AF representing a common phenotype for the multiple pathways.¹ Conditions such as hypertension, coronary artery disease, valvular abnormalities, and heart failure lead to increased left atrial pressure, atrial dilation, and atrial wall stress, resulting in structural abnormalities of the atrium such as myocardial fibrosis and/or hypertrophy. These structural changes, or other sources of atrial inflammation, increase susceptibility to AF from ectopic triggers and cause conduction abnormalities that promote re-entry. Rapidly firing ectopic AF triggers often originate in the pulmonary veins. Other mechanisms involved in AF initiation include activation of the parasympathetic and/or sympathetic autonomic nervous system, which is thought to be related to the plexi of autonomic ganglia located near the left atrial and pulmonary vein junctions. Once initiated, AF itself promotes further structural and electrical remodeling, which underlies the saying “AF begets AF.”^1,9

Atrial Fibrillation Symptom Perception

Between 10-40% of individuals with AF are asymptomatic, termed “silent AF”.¹¹ Thus, most AF patients experience arrhythmia-related symptoms. The most common symptoms reported in association with AF include fatigue, shortness of breath, palpitations, chest pain/discomfort, and dizziness, the first two symptoms being the most common.^1,9 AF symptoms often impact daily activities through exercise intolerance and arrhythmia-related psychological distress, thereby reducing quality of life.¹² Individuals with symptomatic AF describe the experience as unpredictable and emotionally burdensome.⁶

A variety of pathophysiologic mechanisms influence the perception of AF symptoms including the loss of atrioventricular synchrony, tachycardia, reduced cardiac output, decreased left ventricular diastolic and/or systolic function, and impaired myocardial perfusion.⁵ Mechanisms other than arrhythmia occurrence and altered hemodynamics are involved in AF symptom perception. Arrhythmia episodes may not correlate well with AF symptom reports: Many individuals experience symptoms during some, but not all, AF episodes.^{9, 13} Further, some patients report AF symptoms during sinus rhythm.¹⁴ Variations in autonomic tone (the balance of parasympathetic and sympathetic input to the cardiac autonomic ganglia) likely influence whether an individual perceives AF symptoms.^15,16 Higher levels of anxiety and depression are associated with a greater frequency and severity of AF symptoms.¹⁷ The number and severity of AF symptoms increases in the setting of certain comorbidities, including heart failure, diabetes, obesity, and coronary artery disease.^18-20 Individuals with paroxysmal AF are more likely to experience palpitations,¹⁸ whereas individuals with persistent AF tend to have more fatigue and dyspnea.¹⁹

Several sociodemographic characteristics have also been associated with variations in the presence, type, or severity of AF symptoms. Palpitations are more common in younger individuals, whereas older adults may experience nonspecific AF symptoms (fatigue, dyspnea).^18,20,21 Women are more likely to experience most AF symptoms, and with greater severity than men.^20-22 Specifically, women are more likely than men to experience palpitations, dyspnea, lightheadedness, fatigue, and chest discomfort.^21,22 Caucasians tend to experience less severe symptoms than members of other racial and ethnic groups.^23,24 An important gap in the literature relates to whether there are inherent differences in symptom mechanisms based on gender and race/ethnicity. Notably, evidence from a large cohort study and a systematic review show that women and underrepresented racial/ethnic minorities are less likely to undergo several procedures used for AF symptom management including electrical cardioversions, AF ablations, and MAZE surgeries.^24,25 Further research exploring the reasons for gender, racial, and ethnic differences in AF clinical management are warranted.

Clinical Implications for Nurse Practitioners

Nurse practitioners (NP) can play a critical role in AF management by ensuring patients receive appropriate diagnosis and symptom management regardless of their symptom presentation. During the diagnostic process NPs should be aware that AF symptoms are often nonspecific (dyspnea, fatigue) and can be intermittent. This leads some patients to delay seeking treatment, particularly if they associate the symptoms with deconditioning or part of the normal aging process.²⁶ Additionally, qualitative research indicates some healthcare providers dismiss patients’ symptoms as insignificant or inappropriately attribute symptoms to other conditions (e.g. panic attacks),²⁷ likely contributing to delayed diagnosis. The presence, type, number, or severity of AF symptoms (i.e. nonspecific, intermittent) does not align with the risk of AF complications, such as ischemic stroke. The consequences of delayed or missed AF diagnosis can be profound (i.e. ischemic stroke), thus requiring vigilance to ensure AF is considered in the differential diagnosis when appropriate. In older adults and individuals with risk factors for AF, any potential AF symptoms warrant further evaluation for this highly prevalent condition.

The setting for evaluation and choice of diagnostic test (12-lead ECG, 24-hour Holter monitor, event monitor, loop recorder) should be guided by the patient’s hemodynamic stability, the severity of AF symptoms, and the nature/frequency of symptoms.^1,9 For example, a 12-lead ECG or 24-hour Holter monitor may be insufficient to diagnose paroxysmal AF in a patient that reports intermittent symptoms that only occur once weekly—in this situation longer-term monitoring would be more appropriate. Multiple options are available for longer-term monitoring including: external loop recorders that can be worn for up to 30 days and provide continuous and event monitoring; patch monitors (e.g. ZIO Patch), adhesive single-lead ECG devices that provide continuous and event monitoring for 1-3 weeks; implantable loop recorders that provide continuous and event recordings and last up to 3 years; or newer direct to consumer smartphone options, such as AliveCor® Kardia Mobile, a device that pairs with specific smartphones to provide 30-second single-lead ECG recordings at the moment an individual experiences symptoms.²⁸ Joint decision making to determine the most appropriate approach to monitoring should include consideration of the frequency and duration of symptoms and resource availability (i.e. provider that can implant a loop recorder; patient’s ability and willingness to purchase a direct to consumer smartphone device). Direct to consumer smartphone devices were recently integrated into clinical practice guidelines as an option for post AF ablation arrhythmia recurrence monitoring. These devices offer a new option for long-term monitoring of AF recurrence, symptom management, and AF symptom-rhythm correlation. Smartphone ECG monitoring could be particularly useful in rural or low-resource areas where access to medical care is limited and/or requires traveling long distances.²⁹

NPs can advocate for patients to ensure that symptoms are appropriately managed, and that quality of life is optimized. To ensure a full cardiovascular risk factor evaluation is completed, referral to a cardiology or cardiac electrophysiology clinic is appropriate for patients initially diagnosed in another setting, such as primary care, when referral is feasible and available: Refer early if guidance is needed to select an appropriate antithrombotic treatment strategy. A complete discussion of initial AF evaluation is beyond the scope of this article, but should include the presence, type, and severity of symptoms and evaluation for underlying heart disease or reversible etiology (e.g. valvular disease, left ventricular hypertrophy, hyperthyroidism, heavy alcohol consumption).¹ Additional testing that may be required based on history, physical, and diagnostic exam results include: exercise testing, heart monitoring, transesophageal echocardiogram (i.e. if left atrial thrombus is suspected), and/or electrophysiological study (i.e. if atrial flutter is suspected as a predisposing factor for AF).¹ Initial education should include informing patients of the importance of adherence to anticoagulation therapy even during asymptomatic periods, as asymptomatic or minimally-symptomatic status does not alter the risk of stroke.

Appropriate ventricular heart rate control (<80 beats per minute at rest¹) is essential both to prevent complications (tachycardia-mediated cardiomyopathy) and to manage symptoms. If the ventricular heart rate is sufficiently controlled but the patient remains symptomatic, the patient should be provided with rhythm-control options for the restoration and maintenance of sinus rhythm (e.g. antiarrhythmic medications, direct current cardioversion, or catheter ablation), which may require referral to a cardiac electrophysiology or AF specialty clinic.^1,9 Particular attention should be paid to the sufficiency of symptom management in patient-groups that tend to perceive more severe AF symptoms (women and racial/ethnic minorities) yet receive procedural AF symptom management at lower rates. NPs can advocate for their female and racial/ethnic minority patients by ensuring timely referral to specialty providers that can provide advanced AF symptom management, and by educating patients on the full range of symptom management strategies available for AF.

Conclusion

NPs play an important role in chronic disease management. For patients with AF, the NP can provide caring reassurance regarding patients’ AF symptoms and concerns, educate and treat patients based on evidence-based and consensus guidelines, and provide referrals to appropriate specialty providers to ensure the patient has access to all potential symptom management options.

Highlights.

• Atrial fibrillation (AF) is characterized by heterogenous symptom presentation

• AF symptoms are often nonspecific: fatigue and dyspnea are common AF symptoms

• Timely diagnosis requires consideration of the often intermittent nature of AF