What is paroxysmal atrial fibrillation (AFib) in older adults with a history of cardiovascular issues or risk factors such as hypertension, diabetes, or heart disease?

What is Paroxysmal Atrial Fibrillation?

Paroxysmal atrial fibrillation is a self-terminating form of atrial fibrillation where episodes spontaneously resolve, typically within 48 hours but by definition within 7 days, after which the heart returns to normal sinus rhythm. 1

Clinical Definition and Time Course

Paroxysmal AF is distinguished from other AF types by its self-terminating nature within 7 days of onset. 1 The key temporal features include:

• Episodes lasting from seconds to hours, though they can persist up to 7 days before spontaneous termination 1
• The 48-hour mark is clinically critical because spontaneous conversion likelihood drops significantly after this point, and anticoagulation considerations change 1
• Episodes may recur repeatedly over years in the same patient 1
• Duration must exceed 30 seconds to be classified as a true AF episode 1

Electrocardiographic Features

On ECG, paroxysmal AF demonstrates the same characteristics as other AF forms during episodes:

• Absence of discernible, regular P waves 1
• Irregular ventricular excitation and rhythm 1
• Uncoordinated electrical activation of the atria 1

Epidemiology in Older Adults with Cardiovascular Risk Factors

The prevalence and risk profile are particularly important in your patient population:

• AF prevalence increases dramatically with age, from less than 1% before age 50 to 8% in those over 80 years 1, 2
• Approximately 2.3 million people in North America have paroxysmal or persistent AF 1
• More than 70% of AF patients are older adults with structural heart disease 1

Specific Risk Factors in Your Population

Hypertension is the most common cardiovascular condition associated with paroxysmal AF in older adults, present in approximately 88% of AF patients. 2, 3 Additional critical risk factors include:

• Coronary artery disease promotes AF through atrial ischemia, structural remodeling, and increased left atrial pressure 4, 2
• Heart failure increases 3-year AF incidence to approximately 10%, with bidirectional causality 2
• Diabetes mellitus, particularly in women, increases AF risk 2, 5
• Left ventricular hypertrophy creates the substrate for AF development 2

Pathophysiology in Cardiovascular Disease

Understanding the mechanisms helps explain why your patients develop paroxysmal AF:

• Age-related atrial fibrosis replaces approximately 0.5-1.0% of cardiomyocytes per year with fibrous tissue, disrupting electrical coupling 2
• Hypertension causes left atrial dilation and increased wall stress, promoting electrical remodeling 4, 2
• CAD causes atrial ischemia and activates the renin-angiotensin-aldosterone system, generating profibrotic factors 4
• Obesity promotes AF through progressive left atrial enlargement correlating with body mass index 4, 2

Natural History and Progression

Paroxysmal AF is not a static condition—approximately 30% of patients with paroxysmal AF progress to persistent or permanent AF over time. 5 Recent data shows:

• AF burden increases progressively, with average daily burden rising from 3.2% to 6.1% over one year 6
• 22% of patients show progression to longer AF episodes within 6-12 months 6
• 3% develop persistent AF within one year 6
• One-third of patients may have no AF episodes during 6-month monitoring periods 6

Critical Clinical Implications

When paroxysmal AF develops in the setting of acute myocardial infarction, it portends particularly adverse prognosis compared to patients maintaining sinus rhythm. 4 Key considerations:

• Always screen for acute MI when AF develops acutely, as this combination carries particularly poor prognosis 4
• New-onset AF in CAD patients should not be dismissed as coincidental—it represents active disease interaction requiring aggressive management of both conditions 4
• Women over age 75 with AF face particularly high stroke risk 2

Distinction from Secondary AF

Paroxysmal AF occurring in the setting of acute MI, cardiac surgery, pericarditis, myocarditis, hyperthyroidism, or acute pulmonary disease is considered secondary AF and treated differently. 1 In these situations:

• AF is not the primary problem 1
• Concurrent treatment of the underlying disorder usually terminates the arrhythmia 1
• The general principles for AF management apply only when AF occurs with well-controlled concurrent disorders 1

Common Pitfall: Drug-Induced AF

An increasingly recognized cause of paroxysmal AF in older adults is drug-induced atrial fibrillation (DIAF), particularly in patients on polypharmacy. 1, 2 This is especially relevant because:

• DIAF is not mentioned in major AF management guidelines 1
• Most DIAF episodes are paroxysmal and may terminate spontaneously 1
• Risk increases dramatically in elderly patients with multiple cardiovascular medications and anticancer drugs 1, 2
• Always consider whether a new medication may be responsible for new-onset AF episodes 1

Temporal Patterns Vary Widely

Paroxysmal AF is not a single entity—temporal patterns differ substantially between patients, suggesting heterogeneous underlying mechanisms. 6 Clinical patterns include:

• Patients with long episodes (>12 hours) are often men with more comorbidities, particularly heart failure and coronary artery disease 6
• Patients with higher AF burden (>2.5%) are older with worse renal function and more vascular disease 6
• AF burden is generally low and determined by the number of comorbidities 6