A 70-year-old man comes to the medicine OPD with palpitations for 2 days. His pulse is irregularly irregular at 130/min, with a pulse deficit. The ECG shows narrow QRS complexes, no distinct P waves, a fine undulating baseline and R-R intervals that vary with no pattern. What is the most likely rhythm?

Atrial flutter with variable block

A 45-year-old woman with known breast cancer comes to casualty with breathlessness and dizziness. Pulse 124/min, BP 86/64 mmHg falling by 16 mmHg on inspiration; neck veins are distended and heart sounds are muffled. The ECG shows sinus tachycardia with low-voltage QRS complexes whose height alternates from beat to beat. What is the next best step?

Urgent coronary angiography and PCI

A 76-year-old man has episodes of palpitations followed by dizziness and has had one fall. A Holter shows bursts of atrial fibrillation at 140/min that end in sinus pauses of up to 4.5 seconds, with sinus bradycardia of 40/min between episodes. Which step should come first?

Permanent pacemaker, then rate-control drugs

Metoprolol alone for rate control

Amiodarone alone to keep sinus rhythm

ECG interpretation and arrhythmias

35 NEET-PG practice questions on ECG interpretation and arrhythmias, part of General Medicine. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
A 70-year-old man comes to the medicine OPD with palpitations for 2 days. His pulse is irregularly irregular at 130/min, with a pulse deficit. The ECG shows narrow QRS complexes, no distinct P waves, a fine undulating baseline and R-R intervals that vary with no pattern. What is the most likely rhythm?
1. AAtrial fibrillation
2. BSinus arrhythmia
3. CMultifocal atrial tachycardia
4. DAtrial flutter with variable block
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Answer: A · Atrial fibrillation
Chaotic atrial activity with no organised P waves, a fibrillatory baseline and irregularly irregular R-R intervals is atrial fibrillation. The pulse deficit occurs because short R-R intervals give beats too weak to reach the wrist. The next decisions are rate or rhythm control and stroke prevention, guided by the CHA2DS2-VASc score.
- B: Sinus arrhythmia has a normal P wave before every QRS and varies with breathing.
- C: Multifocal atrial tachycardia has distinct P waves of at least three shapes before each QRS.
- D: Flutter shows regular saw-tooth F waves at about 300/min, even when the block varies.
Question 2 · Medium
A 45-year-old woman with known breast cancer comes to casualty with breathlessness and dizziness. Pulse 124/min, BP 86/64 mmHg falling by 16 mmHg on inspiration; neck veins are distended and heart sounds are muffled. The ECG shows sinus tachycardia with low-voltage QRS complexes whose height alternates from beat to beat. What is the next best step?
1. AIV nitroglycerin infusion
2. BEcho-guided pericardiocentesis
3. CIV furosemide
4. DUrgent coronary angiography and PCI
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Answer: B · Echo-guided pericardiocentesis
Hypotension, raised neck veins and muffled heart sounds (Beck's triad) with pulsus paradoxus point to cardiac tamponade, here probably from a malignant effusion. Electrical alternans, the beat-to-beat change in QRS height, reflects the heart swinging within a large effusion, and low voltage comes from the fluid around the heart. Echo confirms the effusion and chamber collapse, and urgent pericardiocentesis relieves it. The fluid is sent for cytology.
- A: Nitrates reduce preload and can cause collapse in tamponade.
- C: Diuretics lower the filling pressure the heart depends on and worsen tamponade.
- D: There is no evidence of an acute coronary event.
Question 3 · Hard
A 22-year-old trainee pilot is brought to the emergency department of a Pune hospital with sudden palpitations and light-headedness that began an hour ago while jogging. A routine ECG last year, filed in his medical record, showed a PR interval of 0.10 s with a slurred initial QRS upstroke. Now his pulse is about 220/min and irregular, BP is 112/74 mmHg, and he is alert and talking. The monitor shows an irregularly irregular tachycardia with broad QRS complexes whose width and shape vary from beat to beat; the shortest R-R interval is 200 ms. Potassium is 4.2 mmol/L. Which drug is the best choice?
1. AIV metoprolol
2. BIV diltiazem
3. CIV adenosine
4. DIV procainamide
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Answer: D · IV procainamide
An irregular broad-complex tachycardia with varying QRS width in WPW is atrial fibrillation conducting down the accessory pathway; a shortest pre-excited R-R of 250 ms or less marks a dangerous pathway. Blocking the AV node with adenosine, verapamil, digoxin or beta-blockers leaves the pathway as the only route and can accelerate the ventricular rate into ventricular fibrillation. A drug that slows conduction in the pathway, such as procainamide or ibutilide, is used in a stable patient, and synchronised cardioversion if he becomes unstable. Later, ablation of the pathway is curative.
- A: A beta-blocker slows only the AV node and can leave the pathway to conduct even faster.
- B: Diltiazem blocks the AV node, favours the pathway and can precipitate VF.
- C: Adenosine can enhance conduction over the pathway and cause VF.
Question 4 · Medium
A 76-year-old man has episodes of palpitations followed by dizziness and has had one fall. A Holter shows bursts of atrial fibrillation at 140/min that end in sinus pauses of up to 4.5 seconds, with sinus bradycardia of 40/min between episodes. Which step should come first?
1. APermanent pacemaker, then rate-control drugs
2. BMetoprolol alone for rate control
3. CAmiodarone alone to keep sinus rhythm
4. DDigoxin alone for rate control
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Answer: A · Permanent pacemaker, then rate-control drugs
Fast atrial arrhythmias alternating with sinus bradycardia and pauses is the tachycardia-bradycardia form of sick sinus syndrome. Drugs that slow the fast episodes would worsen the pauses and bradycardia, so a permanent pacemaker is placed first; rate-controlling drugs can then be used safely. His stroke risk from atrial fibrillation must also be assessed for anticoagulation. Sick sinus syndrome is a common reason for pacing in the elderly.
- B: Beta-blockers alone would deepen the bradycardia and lengthen the pauses.
- C: Amiodarone alone would slow the sinus node further and risk longer pauses.
- D: Digoxin alone would worsen sinus node depression and pauses.
Question 5 · Medium
A 30-year-old construction worker is pulled out after being trapped under a collapsed wall for 6 hours. He passes dark urine; CK is 48,000 U/L and creatinine 2.6 mg/dL, and serum potassium is awaited. The resident lists ECG findings that would fit severe hyperkalaemia: 1. Tall, narrow, peaked T waves. 2. Flattened or absent P waves with a long PR interval. 3. Widening of the QRS complex. 4. Prominent U waves. Which of these are correct?
1. A1, 3 and 4 only
2. B1 and 3 only
3. C1, 2, 3 and 4
4. D1, 2 and 3 only
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Answer: D · 1, 2 and 3 only
Statements 1, 2 and 3 are correct. Rhabdomyolysis releases potassium from damaged muscle while acute kidney injury reduces its excretion, so hyperkalaemia can rise quickly. The ECG changes progress from peaked T waves to loss of P waves with a long PR, then a broad QRS that can merge into a sine-wave pattern before ventricular fibrillation or asystole. Statement 4 is false: U waves are a feature of hypokalaemia.
- A: Includes U waves, which belong to hypokalaemia, and omits P-wave changes.
- B: Omits the P-wave flattening and PR prolongation, which are part of the progression.
- C: Includes statement 4, which describes hypokalaemia.
Question 6 · Medium
A 67-year-old man is brought to casualty with severe chest pain and sweating for one hour. BP 94/60 mmHg. His ECG shows ST elevation of 2 mm in aVR, with horizontal ST depression of 2-3 mm in leads I, II, aVL and V3-V6. What does this pattern most strongly suggest?
1. AIsolated right coronary artery occlusion
2. BLeft main or three-vessel coronary disease
3. CAcute pericarditis
4. DIsolated posterior wall infarction
Answer and explanation in LearnFree account
Question 7 · Hard
A 23-year-old engineering student is brought to casualty by her hostel warden 2 hours after swallowing a strip of her mother's amitriptyline tablets after a quarrel. She is drowsy but rousable, with dilated pupils, dry flushed skin, a palpable bladder and absent bowel sounds. Pulse is 132/min, BP 92/58 mmHg, temperature 37.8°C. During assessment she has a brief generalised seizure. The ECG shows sinus tachycardia, QRS duration 150 ms, a tall terminal R wave in aVR and a long QT interval. Arterial pH is 7.31. Which treatment best addresses the ECG abnormality?
1. AIV sodium bicarbonate
2. BIV flumazenil and naloxone
3. CIV amiodarone
4. DIV physostigmine
Answer and explanation in LearnFree account
Question 8 · Medium
A 61-year-old woman with schizophrenia on haloperidol is admitted to the medical ward with pneumonia; her QTc is 490 ms. Before clarithromycin is started, the house officer lists factors that would further raise her risk of torsades de pointes: 1. Serum potassium 3.0 mmol/L. 2. Serum magnesium 1.2 mg/dL (low). 3. Serum calcium 11.8 mg/dL (high). 4. Adding clarithromycin. Which of these increase the risk?
1. A1, 2, 3 and 4
2. B2, 3 and 4 only
3. C1, 2 and 4 only
4. D1 and 2 only
Answer and explanation in LearnFree account
Question 9 · Medium
A 66-year-old man with back pain and anaemia is admitted with confusion, constipation and polyuria. Serum creatinine is 1.9 mg/dL, and total protein is 9.8 g/dL with albumin 3.1 g/dL. His ECG shows sinus rhythm with a QTc of 330 ms because the ST segment is very short. Which abnormality most likely explains the ECG?
1. AHypokalaemia
2. BHypocalcaemia
3. CHypomagnesaemia
4. DHypercalcaemia
Answer and explanation in LearnFree account
Question 10 · Medium
A 59-year-old man has had three admissions in a year for typical atrial flutter despite drug therapy. An electrophysiology study confirms a counter-clockwise macro-re-entrant circuit around the tricuspid annulus. What is the treatment of choice for a cure?
1. ALifelong oral amiodarone
2. BAV node ablation with a pacemaker
3. CAblation of the cavotricuspid isthmus
4. DPulmonary vein isolation
Answer and explanation in LearnFree account
Question 11 · Medium
A 60-year-old diabetic man has had central chest heaviness for one hour. His ECG shows horizontal ST depression of 3 mm in V1-V3 with tall, broad R waves and upright T waves in V1 and V2; the limb leads are normal. Which step will best confirm the diagnosis?
1. ARepeat the ECG after sublingual nitrate
2. BDo an exercise treadmill test
3. CRecord right-sided lead V4R
4. DRecord posterior leads V7-V9
Answer and explanation in LearnFree account
Question 12 · Easy
During a pre-employment check, a 23-year-old long-distance runner has a Holter recording. During sleep, the PR interval lengthens with each beat until a P wave is not followed by a QRS, after which the cycle repeats; the QRS complexes are narrow. The block is most likely located in the:
1. ASinoatrial node
2. BAV node
3. CHis bundle
4. DBundle branches
Answer and explanation in LearnFree account
Question 13 · Medium
A 42-year-old woman develops sudden breathlessness and pleuritic chest pain on day 6 after a caesarean section. Pulse 118/min, SpO2 89% on room air and BP 108/70 mmHg. A CT pulmonary angiogram is planned. The most common ECG finding in this condition is:
1. ARight axis deviation
2. BNew right bundle branch block
3. CS1Q3T3 pattern
4. DSinus tachycardia
Answer and explanation in LearnFree account
Question 14 · Medium
A 24-year-old woman has exertional breathlessness. There is a wide, fixed split second heart sound and an ejection systolic murmur in the pulmonary area. The ECG shows an rsR' pattern in V1 with QRS 110 ms and left axis deviation of -45°. What is the most likely defect?
1. AOstium primum atrial septal defect
2. BOstium secundum atrial septal defect
3. CPerimembranous ventricular septal defect
4. DSinus venosus atrial septal defect
Answer and explanation in LearnFree account
Question 15 · Hard
A 14-year-old girl is referred to the cardiology OPD after fainting twice while swimming in school competitions; once she was pulled out of the pool unconscious and recovered fully after about a minute, without tongue biting or incontinence. Her hearing is normal and she has no structural heart disease on echo. The ECG shows sinus rhythm at 70/min with a QTc of 510 ms and broad-based T waves; potassium, magnesium and calcium are normal, and she takes no drugs. Her 42-year-old father has a QTc of 480 ms but has never fainted. Genetic testing is awaited. Which long-term drug is most appropriate?
1. AVerapamil
2. BMexiletine
3. CNadolol or propranolol
4. DAmiodarone
Answer and explanation in LearnFree account
Question 16 · Hard
A 59-year-old man is admitted with an acute inferior STEMI. Two hours later his pulse falls to 46/min; BP is 104/70 mmHg and he is alert. The ECG shows complete heart block with a narrow-QRS escape rhythm at 46/min and ST elevation in II, III and aVF. Consider: 1. The block is most likely at the level of the AV node. 2. The usual culprit artery is the right coronary artery. 3. The block often resolves within days after reperfusion. 4. A permanent pacemaker should be implanted before reperfusion. Which statements are correct?
1. A1, 2, 3 and 4
2. B1, 2 and 3 only
3. C2 and 3 only
4. D1, 2 and 4 only
Answer and explanation in LearnFree account
Question 17 · Easy
A 45-year-old woman in Kolkata is admitted with three days of profuse watery diarrhoea and generalised muscle weakness. Her ECG shows flattened T waves, ST depression and a prominent extra wave after the T wave in the precordial leads. Which electrolyte disturbance best explains the ECG?
1. AHyponatraemia
2. BHypercalcaemia
3. CHypokalaemia
4. DHyperkalaemia
Answer and explanation in LearnFree account
Question 18 · Medium
A 74-year-old retired teacher has had two episodes of sudden dizziness in a month. Pulse is 52/min. The ECG shows a constant PR interval of 0.18 s, occasional P waves not followed by a QRS without any prior PR lengthening, and a right bundle branch block pattern. Electrolytes and thyroid tests are normal, and she takes no rate-slowing drug. What is the most appropriate management?
1. APermanent pacemaker implantation
2. BImplantable cardioverter-defibrillator
3. CReassurance and an annual ECG
4. DOral theophylline
Answer and explanation in LearnFree account
Question 19 · Medium
A 38-year-old woman from Assam with rheumatic heart disease has severe mitral stenosis (valve area 0.9 cm²) and has now developed atrial fibrillation; she is awaiting balloon valvotomy. Which drug is preferred for stroke prevention?
1. ARivaroxaban
2. BApixaban
3. CAspirin
4. DWarfarin
Answer and explanation in LearnFree account
Question 20 · Medium
A 52-year-old shopkeeper had three episodes of chest pain at rest over two days. He is now pain-free in the ward, and troponin is only mildly raised. The ECG shows deep, symmetrical T-wave inversion in V2 and V3 with preserved R waves, no Q waves and no ST elevation. What does this pattern most likely indicate?
1. AAcute pericarditis in its late stage
2. BLV hypertrophy with strain
3. CCritical proximal LAD stenosis
4. DOld completed inferior infarction
Answer and explanation in LearnFree account
Question 21 · Medium
A 26-year-old man has had sharp central chest pain for 2 days, worse lying flat and on deep breathing and eased by sitting forward; he had a viral fever a week ago. A scratchy sound is heard at the left sternal edge. ECG: concave-up ST elevation in most leads except aVR and V1, with PR depression. Troponin is normal and echo shows no effusion. What is the best treatment?
1. AIV tenecteplase
2. BNSAID plus colchicine
3. COral prednisolone
4. DCoronary angiography
Answer and explanation in LearnFree account
Question 22 · Medium
An 80-year-old woman living alone in Shimla is found on her kitchen floor on a January morning, drowsy and with cold skin. Pulse 42/min. Her ECG shows sinus bradycardia, a long QT interval, shivering artefact and a positive notch at the junction of the QRS complex and the ST segment in many leads. The notch most likely reflects:
1. ADigoxin toxicity
2. BAcute pericarditis
3. CHyperkalaemia
4. DHypothermia
Answer and explanation in LearnFree account
Question 23 · Hard
A 68-year-old retired railway clerk attends the medicine OPD of a district hospital with two weeks of intermittent palpitations. He has hypertension on amlodipine, type 2 diabetes on metformin, and had an inferior myocardial infarction treated with a stent 3 years ago; he now takes only atorvastatin and a single antiplatelet. The ECG shows atrial fibrillation at 92/min, and a Holter confirms it is persistent. He has no heart failure, no previous stroke or TIA, and his LV ejection fraction is 55%. Creatinine is 1.0 mg/dL and he has never had a major bleed. What is his CHA2DS2-VASc score, and what is the right antithrombotic plan?
1. A3; start oral anticoagulation
2. B4; start oral anticoagulation
3. C4; aspirin plus clopidogrel instead
4. D2; no antithrombotic needed
Answer and explanation in LearnFree account
Question 24 · Medium
A 34-year-old woman with severe asthma, on high-dose inhaled steroids and frequent rescue salbutamol, comes to casualty with a regular narrow-complex tachycardia at 190/min. BP 116/78 mmHg and she is alert. Vagal manoeuvres fail. An old ECG shows no pre-excitation and she takes no beta-blocker. Which drug is the best choice to terminate the tachycardia?
1. AIV propranolol
2. BIV digoxin
3. CIV verapamil
4. DIV adenosine
Answer and explanation in LearnFree account
Question 25 · Easy
A 28-year-old woman comes to casualty with sudden regular palpitations for 40 minutes. Pulse 186/min, BP 118/76 mmHg, and she is alert and comfortable. The ECG shows a regular narrow-complex tachycardia with no visible P waves. A modified Valsalva manoeuvre fails to stop it. Which drug should be given next?
1. AIV digoxin
2. BOral metoprolol
3. CIV adenosine
4. DIV amiodarone infusion
Answer and explanation in LearnFree account

10 more ECG interpretation and arrhythmias questions

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Study General Medicine

ECG interpretation and arrhythmias

A 76-year-old man has episodes of palpitations followed by dizziness and has had one fall. A Holter shows bursts of atrial fibrillation at 140/min that end in sinus pauses of up to 4.5 seconds, with sinus bradycardia of 40/min between episodes. Which step should come first?

A 67-year-old man is brought to casualty with severe chest pain and sweating for one hour. BP 94/60 mmHg. His ECG shows ST elevation of 2 mm in aVR, with horizontal ST depression of 2-3 mm in leads I, II, aVL and V3-V6. What does this pattern most strongly suggest?

A 59-year-old man has had three admissions in a year for typical atrial flutter despite drug therapy. An electrophysiology study confirms a counter-clockwise macro-re-entrant circuit around the tricuspid annulus. What is the treatment of choice for a cure?

A 60-year-old diabetic man has had central chest heaviness for one hour. His ECG shows horizontal ST depression of 3 mm in V1-V3 with tall, broad R waves and upright T waves in V1 and V2; the limb leads are normal. Which step will best confirm the diagnosis?

During a pre-employment check, a 23-year-old long-distance runner has a Holter recording. During sleep, the PR interval lengthens with each beat until a P wave is not followed by a QRS, after which the cycle repeats; the QRS complexes are narrow. The block is most likely located in the:

A 42-year-old woman develops sudden breathlessness and pleuritic chest pain on day 6 after a caesarean section. Pulse 118/min, SpO2 89% on room air and BP 108/70 mmHg. A CT pulmonary angiogram is planned. The most common ECG finding in this condition is:

A 24-year-old woman has exertional breathlessness. There is a wide, fixed split second heart sound and an ejection systolic murmur in the pulmonary area. The ECG shows an rsR' pattern in V1 with QRS 110 ms and left axis deviation of -45°. What is the most likely defect?

A 45-year-old woman in Kolkata is admitted with three days of profuse watery diarrhoea and generalised muscle weakness. Her ECG shows flattened T waves, ST depression and a prominent extra wave after the T wave in the precordial leads. Which electrolyte disturbance best explains the ECG?

A 38-year-old woman from Assam with rheumatic heart disease has severe mitral stenosis (valve area 0.9 cm²) and has now developed atrial fibrillation; she is awaiting balloon valvotomy. Which drug is preferred for stroke prevention?