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Atrial Fibrillation

Atrial vs Ventricular Fibrillation – High‑Yield Review for NEET PG | atsixty.com

Atrial Fibrillation vs Ventricular Fibrillation – High‑Yield Review

Target audience: MBBS doctors preparing for NEET PG / INI‑CET / CMS.

Atrial fibrillation (AF) and ventricular fibrillation (VF) are commonly tested arrhythmias with entirely different clinical urgency. AF is usually compatible with life but carries long‑term thromboembolic risk, whereas VF is immediately fatal unless treated within minutes. This short note focuses only on exam‑relevant and bedside‑relevant facts. Jump to Test Yourself (MCQs)

Side‑by‑side ECG comparison of atrial fibrillation and ventricular fibrillation
ECG comparison: atrial fibrillation (left) vs ventricular fibrillation (right).

Atrial Fibrillation (AF)

  • Definition: Chaotic atrial electrical activity causing loss of coordinated atrial contraction and an irregularly irregular ventricular rhythm.
  • Common causes: Hypertension, coronary artery disease, rheumatic mitral stenosis (classic), hyperthyroidism, alcohol (“holiday heart”), post‑cardiac surgery.
  • ECG hallmarks: Absence of P waves, presence of fibrillatory (f) waves, irregular RR intervals, usually narrow QRS.
  • Hemodynamic effect: Loss of atrial kick → reduced cardiac output, more significant in elderly and diastolic dysfunction.
  • Major complication: Thromboembolism, especially ischemic stroke due to clot formation in the left atrial appendage.
  • Management principles:
    • Rate control: β‑blockers, diltiazem, verapamil; digoxin preferred in heart failure.
    • Rhythm control: amiodarone or electrical cardioversion in selected patients.
    • Anticoagulation guided by CHA₂DS₂‑VASc score.
    • Definitive option: catheter ablation (pulmonary vein isolation).

Ventricular Fibrillation (VF)

  • Definition: Rapid, disorganized ventricular electrical activity resulting in no effective cardiac output.
  • Most common cause: Acute myocardial infarction.
  • Other causes: Hypoxia, acidosis, hypokalemia, hypomagnesemia, drug toxicity, cardiomyopathy.
  • ECG features: Completely chaotic waveform with no identifiable P waves, QRS complexes or T waves.
  • Clinical presentation: Sudden cardiac arrest – patient is pulseless and unconscious.
  • Management:
    • Immediate defibrillation – single most important life‑saving step.
    • High‑quality CPR.
    • Epinephrine and amiodarone.
    • Post‑ROSC: identify reversible causes and consider ICD for secondary prevention.

AF vs VF – Key Exam Differences

FeatureAtrial FibrillationVentricular Fibrillation
Chamber involvedAtriaVentricles
PulsePresent, irregularAbsent
Immediate riskStrokeSudden death
ECGNo P waves, irregularly irregularChaotic baseline
First‑line actionRate control + anticoagulationDefibrillation

High‑Yield Clinical Pearls

  • AF is never an indication for emergency defibrillation unless associated with instability.
  • VF should never be treated with drugs before attempting defibrillation.
  • Always think of AF when the pulse is irregularly irregular.

Take‑home message: AF is a chronic arrhythmia with thromboembolic implications; VF is an electrical catastrophe requiring instant shock. Confusing the two in exams or emergencies can be fatal.

© atsixty.com – concise medical notes for postgraduate entrance preparation.

Test Yourself: Atrial vs Ventricular Fibrillation

Quick revision MCQs for NEET PG / INI-CET

Atrial Fibrillation

Total Questions: 16

Question 1

A chronic alcoholic develops a paroxysm of palpitations after alcohol binge. Which of the following Arrhythmia is most likely?
1. Ventricular fibrillation
2. Ventricular premature complex
3. Atrial flutter
4. Atrial fibrillation

Question 2

A 58-year-old chronic alcoholic presents to the emergency department 18 hours after a weekend binge with complaints of irregular, rapid palpitations. He is conscious, oriented, and hemodynamically stable. ECG shows irregularly irregular rhythm with absent P waves. Which mechanism is LEAST likely to contribute to this arrhythmia?
1. Atrial stretch from volume expansion
2. Electrolyte depletion, particularly magnesium
3. Shortened atrial refractory period
4. Decreased sympathetic tone

Question 3

A 62-year-old man with chronic alcohol use develops atrial fibrillation after binge drinking. Which statement regarding management is MOST accurate?
1. Anticoagulation is unnecessary as the episode is self-limiting
2. Beta-blockers are contraindicated in alcohol-related AF
3. The arrhythmia typically resolves within 24 hours with abstinence
4. Cardioversion should be performed immediately in all cases

Question 4

A patient develops atrial fibrillation 24 hours after heavy alcohol consumption. His CHA₂DS₂-VASc score is 3. Which statement is correct?
1. Anticoagulation is not needed for paroxysmal AF
2. The stroke risk should be assessed even though the episode may be transient
3. Aspirin alone is sufficient for stroke prevention
4. Anticoagulation can be deferred until AF becomes permanent

Question 5

A patient with CAD and diabetes has CHA₂DS₂-VASc score of 4 and develops paroxysmal AF after alcohol binge. What is the PRIMARY reason for anticoagulation consideration?
1. The episode lasted more than 48 hours
2. Even paroxysmal AF carries stroke risk
3. Alcohol causes hypercoagulability
4. Beta-blockers require anticoagulation coverage

Question 6

A 65-year-old chronic alcoholic presents with palpitations. ECG shows irregularly irregular rhythm at 130 bpm with no P waves. BP is 145/85 mmHg. He is alert and oriented. What is the MOST appropriate initial management?
1. Rate control with beta-blocker or calcium channel blocker
2. Immediate electrical cardioversion
3. High-dose amiodarone loading
4. Observation only without medication

Question 7

A chronic alcoholic with new-onset AF has the following: Age 72, diabetes, hypertension, prior stroke. What is his CHA₂DS₂-VASc score?
1. 3
2. 4
3. 5
4. 6

Question 8

A patient with Holiday Heart AF receives metoprolol for rate control. What electrolyte should be URGENTLY repleted?
1. Calcium
2. Magnesium
3. Phosphate
4. Chloride

Question 9

Which diagnostic test is LEAST useful in the initial workup of suspected Holiday Heart Syndrome?
1. Electrocardiogram
2. Serum electrolytes (K⁺, Mg²⁺, Ca²⁺)
3. Cardiac MRI
4. Thyroid function tests

Question 10

An elderly-man with history of Diabetes mellitus and Coronary Artery Disease comes for follow-up, with complaints of muscle pains. Which one of the following drugs could be the most likely cause?
1. Aspirin
2. Glimepiride
3. Enalapril
4. Atorvastatin

Question 11

A 68-year-old man with diabetes and CAD on atorvastatin 80 mg develops muscle pain. His creatine kinase is 450 IU/L (normal <200). What is the MOST appropriate next step?
1. Immediately discontinue the statin permanently
2. Continue statin and recheck CK in 1 week
3. Switch to ezetimibe monotherapy
4. Reduce atorvastatin dose to 40 mg and monitor

Question 12

Statin-associated muscle symptoms (SAMS) affect what percentage of statin users in clinical practice?
1. 1-3%
2. 7-29%
3. 40-50%
4. 60-70%

Question 13

A patient cannot tolerate any statin despite multiple attempts. Which alternative provides the greatest LDL reduction?
1. Ezetimibe alone
2. PCSK9 inhibitor
3. Bile acid sequestrant
4. Niacin

Question 14

A patient with prior MI and diabetes has LDL of 95 mg/dL on atorvastatin 20 mg but develops myalgia. What is the target LDL for this very high-risk patient?
1. <100 mg/dL
2. <70 mg/dL
3. <55 mg/dL
4. <40 mg/dL

Question 15

A patient develops muscle pain on atorvastatin. After stopping the statin for 3 weeks, symptoms resolve. What rechallenge strategy is MOST appropriate?
1. Resume atorvastatin 80 mg
2. Try pravastatin 40 mg (hydrophilic statin)
3. Never use any statin again
4. Wait 6 months before any rechallenge

Question 16

A 70-year-old on atorvastatin, amlodipine, and clarithromycin for pneumonia develops severe myalgia. What is the MOST likely explanation?
1. Pneumonia causes myalgia
2. Drug interaction between clarithromycin and atorvastatin
3. Amlodipine-induced myopathy
4. Age-related muscle weakness

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