About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
The Bottom Line
- Palpitations are extremely common and usually benign — but must exclude dangerous arrhythmias (AF, VT) and treatable secondary causes
- Key history: onset/offset (sudden = SVT/VT, gradual = sinus tach), regularity (irregular = AF, PVCs), associated symptoms (syncope, chest pain, dyspnea = red flags)
- All patients need: 12-lead ECG (may show WPW, long QT, prior MI, AF, or be normal), CBC (anemia), TSH (thyrotoxicosis), electrolytes (K+, Mg2+, Ca2+)
- If ECG normal and episodes infrequent: ambulatory monitoring (Holter 24-48h, event monitor 2-4 weeks, or implantable loop recorder for very infrequent episodes)
- Symptom-rhythm correlation is the diagnostic goal — matching the patient's reported symptoms to a documented rhythm on ECG or monitor
Approach to the Presentation
Palpitations are the subjective awareness of one's heartbeat — described as fluttering, pounding, racing, skipping, or flip-flopping. They account for ~15% of outpatient cardiology referrals. The diagnostic challenge is that palpitations are intermittent and often not present at the time of evaluation. The approach involves: (1) determining whether the palpitations represent a benign or dangerous rhythm; (2) identifying secondary causes (thyroid, anemia, drugs, caffeine, anxiety); (3) achieving symptom-rhythm correlation through monitoring. Most palpitations (~40%) are due to premature beats (PACs/PVCs), ~30% are anxiety-related, and only ~10-15% represent clinically significant arrhythmias.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Ventricular Tachycardia | must-not-miss | Sudden onset, associated syncope/presyncope, history of structural heart disease (prior MI, HFrEF, HCM). Wide QRS on ECG. May be hemodynamically unstable | 12-lead ECG during episode (wide complex regular tachycardia) |
| Atrial Fibrillation / Flutter | must-not-miss | Irregularly irregular pulse, may be sustained or paroxysmal. Risk factors: age, HTN, valvular disease, OSA, alcohol, thyroid. Stroke risk | ECG: absent P waves, fibrillatory baseline, irregularly irregular QRS |
| WPW (pre-excitation) with SVT | must-not-miss | Young patient, sudden-onset rapid palpitations. Risk of degeneration to VF if AF develops over accessory pathway | ECG in sinus rhythm: short PR + delta wave + wide QRS |
| SVT (AVNRT / AVRT) | common | Sudden onset and offset ("like a switch"), regular rapid rate 150-250 bpm, neck pounding (AVNRT), post-episode polyuria | ECG during episode: regular narrow-complex tachycardia. Terminates with vagal maneuvers or adenosine |
| Premature Atrial/Ventricular Complexes (PACs/PVCs) | common | Skipped beats, flip-flopping, occur at rest or with stimulants. Generally benign if structurally normal heart | ECG or Holter: isolated premature beats. PVC burden <10% usually benign |
| Sinus Tachycardia (secondary cause) | common | Gradual onset, rate proportional to stimulus. Causes: exercise, fever, anemia, dehydration, thyrotoxicosis, anxiety, medications (salbutamol, caffeine), PE | ECG: normal P waves before each QRS, rate <220 minus age. Treat underlying cause |
| Anxiety / Panic Disorder | common | Associated hyperventilation, perioral tingling, sense of doom, chest tightness. Often situational. Diagnosis of exclusion | Normal ECG + normal labs + symptom-context correlation |
| Thyrotoxicosis | less common | Palpitations + weight loss, heat intolerance, tremor, diarrhea, lid retraction/lag, thyroid enlargement | TSH (suppressed) + free T4/T3 (elevated) |
Red Flags & Key History
Symptoms
Syncope or presyncope during palpitations — suggests hemodynamically significant arrhythmia (VT, rapid SVT)
Associated chest pain or dyspnea — suggests ischemia or heart failure
Family history of sudden cardiac death at young age — suggests channelopathy (LQTS, Brugada, HCM, ARVC)
Known structural heart disease (prior MI, HF, cardiomyopathy) — higher risk for VT
Sudden onset/offset like a light switch — typical of re-entrant SVT (AVNRT/AVRT)
Irregular skipping sensation — likely PACs or PVCs
Worse with caffeine, alcohol, decongestants, stimulants — suggests enhanced automaticity
Signs
Irregularly irregular pulse (AF)
Regular rapid pulse >150 bpm (SVT or VT)
Hypotension or signs of hemodynamic compromise during episode
Thyromegaly, tremor, lid lag (thyrotoxicosis)
Pallor, tachycardia at rest (anemia)
Approach to Investigation
First-line
12-lead ECGEssential even if patient is asymptomatic at time of assessment. Look for: AF, WPW (delta wave + short PR), long QT, Brugada pattern, prior MI (Q waves), LVH (HCM), epsilon waves (ARVC), PVCs. Normal resting ECG does not exclude paroxysmal arrhythmia
CBCRule out anemia (compensatory tachycardia)
TSHRule out hyperthyroidism — always check in new-onset palpitations or AF
Electrolytes (K+, Mg2+, Ca2+)Hypokalemia and hypomagnesemia lower arrhythmia threshold
Second-line
Ambulatory ECG monitoringHolter (24-48h): if episodes daily. Event monitor/patch (2-4 weeks): if episodes weekly. Implantable loop recorder (up to 3 years): if infrequent but clinically significant episodes with syncope. Goal: symptom-rhythm correlation
EchocardiogramIf red flags present, abnormal ECG, or suspected structural heart disease. Assess LVEF, valvular disease, LVH, RVSP
Specialist
EP studyIf SVT or VT documented/suspected with consideration for catheter ablation. Also for risk stratification in WPW
Management Principles
CCS 2020 AF Management Guideline + CCS SVT Position Statement1
Benign palpitations (PACs, PVCs, sinus tach)
- Reassurance — most palpitations are benign
- Lifestyle: reduce caffeine, alcohol, decongestants, stimulants
- Treat underlying cause: anemia (iron), thyrotoxicosis (methimazole/PTU), dehydration (fluids), anxiety (CBT, SSRI)
- If PVCs are frequent and bothersome: beta-blocker (metoprolol). If PVC burden >10-15% with LV dysfunction: EP referral for ablation
2
SVT (AVNRT/AVRT)
- Acute: vagal maneuvers (modified Valsalva) then IV adenosine 6/12/12 mg. Cardioversion if unstable
- Long-term: catheter ablation (curative >95%). Alternatively: PRN pill-in-the-pocket or daily beta-blocker/CCB
3
Atrial Fibrillation
- Rate control (beta-blocker or diltiazem) + anticoagulation based on CHADS-65 (Canadian: age >=65 or any risk factor = anticoagulate with DOAC)
- Rhythm control if symptomatic: cardioversion + antiarrhythmics or catheter ablation
- Note: Canada uses CHADS-65 (simpler than CHA2DS2-VASc) — if age >=65 OR any of HTN/DM/stroke/HF/vascular disease: anticoagulate
4
Ventricular Tachycardia
- Unstable: cardioversion/defibrillation per ACLS
- Stable: IV amiodarone or procainamide
- Long-term: ICD + address underlying cause (revascularization, GDMT for HF). Catheter ablation for recurrent VT
MCCQE1 Exam Tips
- 1The MCCQE1 tests your approach to the undifferentiated patient with palpitations. The first step is ALWAYS a 12-lead ECG + basic labs (CBC, TSH, lytes)
- 2Sudden onset/offset palpitations = re-entrant SVT. Gradual onset = sinus tachycardia (find the underlying cause)
- 3New-onset AF: always check TSH. In Canada, use CHADS-65 for anticoagulation decisions (simpler than CHA2DS2-VASc)
- 4CHADS-65: age >=65 OR HTN OR DM OR stroke/TIA OR HF OR vascular disease = DOAC. No score calculation needed — any positive criterion = anticoagulate
- 5WPW + AF (irregular wide complex): procainamide or cardioversion. AV-nodal blockers (metoprolol, diltiazem, digoxin, adenosine) are CONTRAINDICATED
- 6PVCs in a structurally normal heart are benign. PVCs in someone with prior MI or HFrEF warrant closer evaluation (echo, Holter, EP referral if burden >10%)
- 7Post-episode polyuria (from ANP release) is a classic clue for SVT (AVNRT)
practicetest your knowledge on palpitationsApply what you've learnt with MCCQE1-style questions from the iatroX Q-Bank — cardiovascular and beyond.
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