Syncope — Written Clinical Reasoning

SAQ — Syncope in an Older Man with Comorbidities (20 marks, 30 minutes)

Prompt: Outline your integrated assessment and management plan for this patient, including the ESC 2018 classification of his syncope, the role of each investigation, the risk stratification, and the evidence-based management strategy. Justify each decision with reference to guidelines and key trials. [1]

Model Answer

Problem list and provisional diagnosis (3 marks): [1]

1. Recurrent syncope — three episodes in 3 months, all in the morning on standing, with a prodrome of light-headedness
2. Orthostatic hypotension — documented: systolic drop of 38 mmHg on standing (146 to 108), exceeding the 20 mmHg threshold for classical OH, with a heart rate rise of only 4 bpm suggesting impaired baroreflex
3. Medication-induced vasodilation — amlodipine (calcium channel blocker) and doxazosin (alpha-blocker) both contribute to OH
4. Structural heart disease — previous MI with LVEF 40 per cent and anterior wall motion abnormality
5. Bifascicular block on ECG — RBBB plus left anterior fascicular block, a high-risk finding
6. Type 2 diabetes — risk of autonomic neuropathy contributing to OH
7. Benign prostatic hyperplasia — reason for doxazosin, which is the most potent medication cause of OH [1]

The provisional diagnosis is multifactorial syncope: orthostatic hypotension from medication-induced vasodilation and possible diabetic autonomic neuropathy is the most likely mechanism, given the morning occurrence, the prodrome, and the documented orthostatic drop. However, the bifascicular block and reduced LVEF mean that an arrhythmic cause (intermittent high-grade AV block or VT) must be excluded. This patient has both a likely explanation (OH) and a high-risk alternative (arrhythmia) that coexist. [1]

ESC 2018 classification (2 marks): [1]

The 2018 ESC guidelines (PMID 29860370) classify syncope into three categories: reflex, orthostatic hypotension, and cardiac. This patient has features of at least two categories: [1]

• Orthostatic hypotension: the morning episodes on standing, the documented orthostatic BP drop, and the medication profile (amlodipine, doxazosin) strongly support this. The minimal heart rate rise on standing (4 bpm) suggests impaired baroreflex function, consistent with autonomic dysfunction from diabetes or age.
• Cardiac (arrhythmic): the bifascicular block on ECG and the reduced LVEF from previous MI raise the possibility of intermittent high-grade AV block or ventricular arrhythmia. While the prodrome and the orthostatic relationship favour OH, the guidelines emphasise that in patients with structural heart disease and abnormal ECG, an arrhythmic cause must be excluded even when another mechanism seems likely. [1]

Risk stratification — this patient is HIGH RISK (3 marks): [1]

The 2018 ESC guidelines define high-risk features warranting admission and expedited workup. This patient has multiple: [1]

• Severe structural heart disease: previous MI with LVEF 40 per cent
• Abnormal ECG: bifascicular block (RBBB plus left anterior fascicular block)
• Recurrent syncope: three episodes in 3 months [1]

Although the episodes have a prodrome and occur on standing (which individually are lower-risk features), the coexistence of structural heart disease and bifascicular block elevates the risk. The guidelines state that patients with syncope and bifascicular block should undergo prolonged ECG monitoring because of the risk of progression to complete heart block. This patient should be admitted for continuous monitoring and expedited cardiac workup. [1]

Investigation plan (5 marks): [1]

1. Continuous ECG monitoring (admission): Given the bifascicular block and reduced LVEF, the patient should be admitted for inpatient continuous telemetry monitoring to detect intermittent high-grade AV block, sinus pauses, or VT. If no arrhythmia is documented during admission, an implantable loop recorder is indicated for long-term monitoring given the infrequent but high-risk nature of the episodes. [1]

2. Carotid sinus massage: This patient is over 40 and has unexplained syncope. Carotid sinus massage should be performed after excluding carotid bruit and cerebrovascular disease, with continuous ECG and BP monitoring, to evaluate for carotid sinus hypersensitivity. The response should be classified as cardioinhibitory (pause of 3 seconds or more), vasodepressor (systolic drop of 50 mmHg or more), or mixed. [1]

3. Repeat echocardiography: The echocardiogram confirms mild LV systolic dysfunction (LVEF 40 per cent) with anterior wall motion abnormality from his previous MI. No significant valvular disease. This helps stratify arrhythmic risk — an LVEF of 40 per cent does not meet the threshold for primary prevention ICD (below 35 per cent), but it does increase the risk of ventricular arrhythmia. [1]

4. Orthostatic blood pressure assessment (extended): The standard 3-minute measurement already shows a significant drop. Given the delayed OH pattern (some episodes may occur after 3 minutes), an extended standing test of 10 minutes should be considered, with blood pressure measured every 1 to 2 minutes. [1]

5. Electrophysiology study: If non-invasive monitoring does not document an arrhythmia, an EP study should be considered to evaluate His-Purkinje conduction (HV interval) and assess for inducible VT, given the structural heart disease and bifascicular block. [1]

6. Blood tests: FBC (exclude anaemia), electrolytes, renal function, HbA1c (diabetes control), and morning cortisol (exclude adrenal insufficiency as a contributor to OH). [1]

Management — orthostatic hypotension (4 marks): [1]

The first and most impactful intervention is medication review: [1]

1. Cease doxazosin: Alpha-blockers are the most potent cause of medication-induced OH. Doxazosin should be ceased and an alternative BPH management strategy used (e.g., tamsulosin has more selective alpha-1A activity and less effect on blood pressure, or a 5-alpha-reductase inhibitor such as finasteride). [1]

2. Reduce or cease amlodipine: Amlodipine contributes to vasodilation. Given the orthostatic drop, it should be reduced or ceased. An alternative antihypertensive with less orthostatic effect (e.g., a low-dose ACE inhibitor or ARB) could be considered if blood pressure remains elevated after the orthostatic component is addressed. [1]

3. Non-pharmacological measures: Adequate hydration (2 to 3 litres per day), salt supplementation if not hypertensive, waist-high compression stockings (20 to 30 mmHg), raised head of bed by 10 to 20 cm, and slow sequential standing (sitting on the edge of the bed for 1 to 2 minutes before standing). [1]

4. If OH persists after medication review and non-pharmacological measures: Consider fludrocortisone 0.1 mg daily (monitoring for supine hypertension, hypokalaemia, and ankle oedema) and/or midodrine 2.5 to 5 mg three times daily (last dose in the early afternoon to avoid supine hypertension; monitor for urinary retention given BPH). [1]

Management — arrhythmic risk (2 marks): [1]

If the implantable loop recorder documents intermittent high-grade AV block or complete heart block (as suggested by the bifascicular block), a permanent dual-chamber pacemaker is indicated. The bifascicular block indicates disease of two of the three fascicles of the His-Purkinje system; syncope in this context is a class I indication for pacing if AV block is documented, and a class IIa indication even without documented AV block if the syncope is unexplained and other causes are excluded. [1]

If VT is documented, management would be guided by the LVEF — with an LVEF of 40 per cent, an ICD may be indicated depending on the VT mechanism and inducibility at EP study. [1]

Communication and driving advice (1 mark): [1]

I would explain that his syncope has multiple contributing factors — his medications, his blood pressure dropping on standing, and the electrical abnormality in his heart that needs monitoring. I would explain that we will first address the medication causes and monitor his heart rhythm. I would advise him not to drive until a definitive diagnosis and treatment are established, given the recurrent episodes and the high-risk features. I would involve his general practitioner in ongoing medication management and arrange follow-up in the cardiology and syncope clinics. [1]