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Palpitations

Chapter 45 | Part 2 – Cardinal Manifestations & Presentation · Part 2 – Cardinal Manifestations & Presentation · Chapter 45

Key Clinical Points

  1. Palpitations are a common symptom with diverse etiologies ranging from benign to life-threatening.
  2. The first step in evaluation is to determine if palpitations are associated with syncope, chest pain, or dyspnea.
  3. ECG during symptomatic episodes is the most important diagnostic test.
  4. Structural heart disease must be ruled out before attributing palpitations to benign causes.
  5. Beta-blockers and calcium channel blockers are first-line for rate control in SVT.
  6. Ablation is indicated for recurrent symptomatic SVT or atrial flutter.
  7. Anxiety and panic disorders are common causes of palpitations in patients with normal cardiac structure.
  8. Caffeine, alcohol, and stimulants can exacerbate palpitations and should be addressed.
  9. Thyroid dysfunction is a reversible cause that must be excluded in all patients.
  10. Orthostatic hypotension and autonomic dysfunction should be considered in elderly patients.

DEFINITION & CLASSIFICATION

• Definition (Harrison's 22e): Palpitations are the subjective sensation of awareness of one's own heartbeat. • Clinical Descriptions: ◦ Patients may describe sensations as: ◦ Pounding or thumping ◦ Racing or fluttering ◦ Skipped or missed beats ◦ Irregular or irregularly irregular rhythm ◦ Chest discomfort associated with awareness of heartbeat • Characteristics of Sensation: ◦ May be intermittent or continuous ◦ Triggered by specific activities, positions, anxiety, or stress ◦ Duration varies from seconds to hours • Classification Systems: ◦ By Rhythm: Regular vs. Irregular ◦ By Rate: Normal vs. Tachycardic vs. Bradycardic ◦ By Origin: Supraventricular vs. Ventricular ◦ By Duration: Paroxysmal vs. Continuous ◦ Alternative Classification: ◦ Benign (sinus tachycardia, premature beats) ◦ Pathologic (arrhythmias, structural disease) ◦ Anxiety-related

EPIDEMIOLOGY

• Prevalence: One of the most common reasons for primary care visits. • Age Distribution: ◦ Prevalence increases with age ◦ Elderly: Higher risk due to structural heart disease, autonomic dysfunction, and medication side effects ◦ Children: Less common unless linked to congenital heart disease, hyperthyroidism, or anxiety disorders • Sex Differences: ◦ Women: Report palpitations more frequently (higher prevalence of anxiety, hormonal influences, lower reporting threshold) ◦ Men: More likely to have ischemic heart disease or structural cardiomyopathy • Risk Factors: ◦ Modifiable: Caffeine, alcohol, nicotine, stimulant medications, dehydration, electrolyte disturbances ◦ Non-modifiable: Age, sex, genetic predisposition to arrhythmias, family history of sudden cardiac death

ETIOLOGY & PATHOPHYSIOLOGY

• Cardiac Causes: ◦ Arrhythmias: SVT (AVNRT, AVRT), Atrial fibrillation (AFib), Atrial flutter, PACs, PVCs, Ventricular tachycardia (VT), Sinus tachycardia ◦ Structural Heart Disease: Coronary artery disease, Cardiomyopathy, Valvular heart disease, Congenital heart defects ◦ Ischemia: Angina with palpitations, Myocardial infarction • Non-Cardiac Causes: ◦ Endocrine: Hyperthyroidism, Hypoglycemia, Pheochromocytoma, Cushing syndrome ◦ Autonomic: POTS (postural orthostatic tachycardia syndrome), Autonomic neuropathy ◦ Medications/Substances: Beta-agonists, Theophylline, Decongestants, Antidepressants, Alcohol, Cocaine, Amphetamines, Cannabis • Pathophysiology of Arrhythmias: ◦ Re-entry mechanisms: AVNRT, AVRT, Atrial flutter, Ventricular tachycardia ◦ Triggered activity: Delayed afterdepolarizations, Early afterdepolarizations ◦ Automaticity: Enhanced automaticity in sinus node, Ectopic automaticity

CLINICAL FEATURES

• Symptom Characteristics: ◦ Onset: ◦ Sudden → suggests arrhythmia ◦ Gradual → suggests sinus tachycardia ◦ Positional → suggests POTS or carotid sinus syndrome ◦ Duration: ◦ Seconds → PACs, PVCs ◦ Minutes → SVT, atrial flutter ◦ Hours to days → Atrial fibrillation ◦ Continuous → Sinus tachycardia ◦ Triggers: ◦ Exercise → sinus tachycardia, ischemia ◦ Rest → arrhythmia, anxiety ◦ Standing → POTS ◦ Alcohol → 'holiday heart' syndrome ◦ Caffeine → enhanced automaticity • Associated Symptoms: ◦ Syncope/Presyncope: Indicates hemodynamic compromise; requires urgent evaluation (may indicate VT, high-grade AV block, severe bradycardia) ◦ Chest pain: Suggests ischemia; may accompany SVT ◦ Dyspnea: May indicate heart failure, pulmonary embolism, or severe arrhythmia ◦ Dizziness: May indicate cerebral hypoperfusion, autonomic dysfunction, or anxiety • Physical Examination Findings: ◦ Vital signs: HR during palpitations, BP (orthostatic), Temperature (thyroid), O_2 saturation ◦ Cardiac exam: Rhythm regularity, S1/S2 intensity, Murmurs (valvular disease), S3/S4 (heart failure) ◦ Peripheral signs: Edema (heart failure), JVD (right heart failure), Cool extremities (shock) ◦ Neurologic exam: Focal deficits (stroke from embolism), Tremor (thyrotoxicosis) • Complications: ◦ Early: Syncope, Falls, Anxiety, Reduced quality of life ◦ Late: Stroke (AFib), Heart failure (tachycardia-induced), Sudden cardiac death (VT), Thromboembolism

DIFFERENTIAL DIAGNOSIS

• Cardiac Differential: ◦ Arrhythmias: Sinus tachycardia, AFib, Atrial flutter, SVT (AVNRT, AVRT), PVCs, PACs, Ventricular tachycardia, Bradycardia ◦ Structural disease: Ischemic heart disease, Cardiomyopathy, Valvular disease, Congenital defects ◦ Pericardial disease: Pericarditis, Pericardial effusion • Non-Cardiac Differential: ◦ Endocrine: Hyperthyroidism, Hypoglycemia, Pheochromocytoma, Cushing syndrome ◦ Autonomic: POTS, Autonomic neuropathy, Carotid sinus syndrome ◦ Psychiatric: Anxiety disorder, Panic disorder, Depression ◦ Medication/Substance: Beta-agonists, Theophylline, Decongestants, Antidepressants, Alcohol, Caffeine, Cocaine, Amphetines • Distinguishing Features: ◦ Arrhythmia vs. Sinus tachycardia: Arrhythmia (sudden onset, irregular) vs. Sinus tachycardia (gradual onset, regular) ◦ Cardiac vs. Anxiety: Cardiac (associated with structural disease) vs. Anxiety (no structural disease, stress-related) ◦ Benign vs. Serious: Benign (PACs, PVCs, sinus tachycardia) vs. Serious (VT, high-grade block, ischemia)

DIAGNOSTIC APPROACH

  1. Initial Evaluation: • Obtain 12-lead ECG during symptoms if possible → assess baseline rhythm, conduction abnormalities, ischemia, and structural changes. • Perform physical exam (vitals, cardiac, neurologic). • Review history (triggers, medications, family history).
  2. Structural Assessment: • Obtain Echocardiogram to evaluate structure, ejection fraction, valvular function, and pericardial disease.
  3. Monitoring for Intermittent Symptoms: • Holter monitor (24-48 hours) → high sensitivity for frequent events. • Event recorder (1-4 weeks) → for infrequent symptoms. • Implantable loop recorder → for cryptogenic syncope.
  4. Laboratory Screening: • TSH → screen for thyroid dysfunction. • CBC → check for anemia. • Electrolytes and Cardiac biomarkers as indicated.
  5. Specialized Testing (if indicated): • Stress testing (Exercise ECG, Stress Echo, Nuclear) → identify exercise-induced symptoms or ischemia. • Electrophysiology study → determine arrhythmia mechanism and plan ablation.

Table 1 — Diagnostic Testing for Palpitations: • 12-lead ECG: Initial evaluation (baseline rhythm/ischemia). • Holter monitor: High sensitivity for frequent events (24-48h). • Event recorder: Moderate sensitivity for infrequent symptoms. • Implantable loop recorder: High sensitivity for cryptogenic syncope. • Echocardiography: High sensitivity for structural heart disease. • TSH: High sensitivity/specificity for thyroid dysfunction. • CBC: High sensitivity for anemia.

Diagnostic Algorithm: 1. Obtain 12-lead ECG during symptoms if possible2. If ECG normal, obtain echocardiogram3. Assess for structural heart disease4. If no structural disease, consider ambulatory monitoring5. Evaluate for non-cardiac causes (thyroid, medications, anxiety)6. If symptoms persist, consider electrophysiology study7. Treat underlying cause or arrhythmia.

MANAGEMENT & TREATMENT

  1. Lifestyle Modifications: • Reduce caffeine intake • Limit alcohol consumption • Avoid nicotine • Manage stress • Regular exercise, adequate sleep, and hydration.
  2. Pharmacologic Therapy (Rate/Rhythm Control): • Beta-blockers: Metoprolol (25-100 mg BID), Atenolol (25-100 mg daily), Propranolol (10-40 mg BID). → Monitor HR, BP; Side effects include fatigue, bradycardia, hypotension. • Calcium channel blockers: Diltiazem (120-360 mg daily), Verapamil (120-480 mg daily). → Monitor HR, BP; Side effects include constipation, edema. • Antiarrhythmics: ◦ Amiodarone (200-400 mg daily) → Monitor TSH, LFT, CXR; Risk of pulmonary fibrosis/thyroid dysfunction. ◦ Sotalol (80-160 mg BID) → Monitor QT interval; risk of proarrhythmia. ◦ Flecainide (50-100 mg BID) → Monitor ECG; avoid in structural heart disease. ◦ Propafenone (150-300 mg BID).

Table 2 — Antiarrhythmic Drug Therapy for Palpitations: • Metoprolol: Beta-blocker, 25-100 mg BID; Contraindicated in asthma/severe bradycardia. • Diltiazem: Non-DHP CCB, 120-360 mg daily; Contraindicated in heart failure/bradycardia. • Amiodarone: Class III, 200-400 mg daily; Monitor TSH/LFT/CXR; Contraindicated in structural disease. • Sotalol: Class III, 80-160 mg BID; Monitor QT interval; Contraindicated in structural disease. • Flecainide: Class IC, 50-100 mg BID; Monitor ECG; Contraindicated in structural disease. 3. Non-Pharmacologic Therapy: • Vagal maneuvers: Valsalva maneuver, Carotid sinus massage, Diving reflex. • Cardioversion: Electrical or Chemical cardioversion. • Ablation: Radiofrequency or Cryoablation (indicated for recurrent SVT, atrial flutter, symptomatic PVCs). • Pacemaker: For symptomatic bradycardia or high-grade AV block. 4. Treatment of Underlying Conditions: • Hyperthyroidism → Antithyroid meds, RAI, or thyroidectomy. • Anxiety disorders → CBT, antidepressants, benzodiazepines (short-term). • Medication/Substance review → Discontinue offending agents; alcohol/nicotine cessation. 5. Monitoring & Follow-up: • Initial: 1-2 weeks post-start to assess symptom control and side effects. • Long-term: Every 3-6 months (or 6-12 if stable) with repeat ECGs and medication review.

PROGNOSIS & COMPLICATIONS

• Prognostic Factors: ◦ Favorable: Benign arrhythmias (PACs, PVCs), anxiety-related palpitations, well-controlled thyroid. ◦ Poor: Ventricular tachycardia, structural heart disease, uncontrolled arrhythmia, syncope with palpitations. • Complication Rates: ◦ Stroke in AFib: 1.5-2% per year without anticoagulation (reduced with anticoagulation). ◦ Heart failure from tachycardia: 10-20% develop HF with sustained tachycardia (reversible with rate control). ◦ Sudden cardiac death: Rare in benign arrhythmias; higher in structural disease. • Long-term Follow-up: ◦ Frequency: Every 3-6 months initially, then every 6-12 months if stable. ◦ Monitoring: ECG, Echocardiogram (periodic), and Ambulatory monitoring as needed. ◦ Medication Review: Every 3-6 months to adjust for side effects or efficacy.