How should a 75‑year‑old man with right bundle branch block (RBBB), hypertension (HTN), chronic mitral regurgitation (MR) and gastro‑oesophageal reflux disease (GERD) presenting with syncope be evaluated and managed?

Evaluation and Management of Syncope in a 75-Year-Old Man with RBBB, HTN, Mitral Regurgitation, and GERD

Immediate Risk Stratification

This patient requires immediate hospital admission for urgent cardiac evaluation. He presents with multiple high-risk features that place him in a category with 18-33% one-year mortality if a cardiac cause is missed: age >60 years, pre-existing right bundle branch block (a bifascicular pattern when combined with any fascicular block carries even higher risk), known structural heart disease (mitral regurgitation), and syncope of unknown etiology 1.

High-Risk Features Present in This Patient

• Age 75 years: Independently predicts adverse outcomes and mandates hospital-based evaluation 1
• Right bundle branch block: RBBB—especially when combined with left anterior or posterior fascicular block (bifascicular block)—is a Class I high-risk ECG feature requiring prompt hospitalization 1
• Known structural heart disease: Chronic mitral regurgitation indicates underlying cardiac pathology with ~95% sensitivity for cardiac syncope 1
• Hypertension: Increases risk of both structural disease and orthostatic hypotension from antihypertensive medications 1

The combination of RBBB and syncope carries particular concern because the most common etiology in this population is paroxysmal atrioventricular block (found in 75-84% of cases), followed by ventricular tachycardia 2, 3, 4.

Mandatory Initial Evaluation (Within First Hour)

Detailed History—Specific Elements to Document

Circumstances of the syncopal event 1, 5:

• Position during syncope: Supine onset strongly suggests cardiac cause; standing suggests reflex or orthostatic mechanism 5
• Activity: Exertional syncope is a Class I indication for immediate cardiac work-up 1
• Prodromal symptoms: Absence of warning symptoms (nausea, diaphoresis, warmth, blurred vision) is a high-risk feature favoring arrhythmic syncope 1, 5
• Palpitations: Palpitations immediately before loss of consciousness strongly indicate arrhythmic cause 1, 5
• Duration of unconsciousness: Prolonged episodes suggest more serious pathology 1
• Recovery phase: Rapid, complete recovery without confusion confirms true syncope rather than seizure 5

Medication review 1, 5:

• Antihypertensives, diuretics, and vasodilators commonly precipitate syncope
• GERD medications (proton pump inhibitors) can cause hypomagnesemia and QT prolongation
• Document all QT-prolonging agents

Cardiac history 1:

• Severity and progression of mitral regurgitation
• Prior episodes of atrial fibrillation
• History of heart failure symptoms
• Family history of sudden cardiac death

Physical Examination—Critical Components

Orthostatic vital signs (mandatory in all patients) 1, 5:

• Measure blood pressure and heart rate supine, seated, and standing
• Orthostatic hypotension: systolic drop ≥20 mmHg or diastolic drop ≥10 mmHg, or standing systolic <90 mmHg 1
• Orthostatic tachycardia: heart rate increase ≥30 bpm within 10 minutes of standing 5

Cardiovascular examination 1:

• Assess mitral regurgitation murmur intensity (holosystolic at apex radiating to axilla)
• Listen for new murmurs, gallops (S3 suggests heart failure), or irregular rhythm
• Evaluate jugular venous pressure and peripheral edema

Carotid sinus massage (Class I recommendation in patients >40 years) 1:

• Contraindications: Prior TIA/stroke within 3 months, carotid bruits unless Doppler excludes significant stenosis 1
• Positive test: Asystole >3 seconds or systolic BP drop >50 mmHg 1

12-Lead ECG—High-Risk Abnormalities to Identify

Conduction system disease 1:

• Document QRS duration (RBBB defined as QRS ≥120 ms)
• Bifascicular block (RBBB + left anterior or posterior fascicular block) is a Class I high-risk feature requiring hospitalization 1
• Look for Mobitz II or third-degree AV block
• Assess PR interval (first-degree AV block increases risk when combined with BBB) 4

Other high-risk ECG findings 1:

• QT prolongation (long QT syndrome)
• Brugada pattern (RBBB with ST elevation in V1-V3)
• Signs of prior MI (pathologic Q waves)
• Left ventricular hypertrophy (suggests severe hypertension or aortic stenosis)
• Atrial fibrillation

Diagnostic Strategy—Three-Phase Approach

Phase I: Immediate Inpatient Cardiac Monitoring

Continuous cardiac telemetry (Class I) 1, 5:

• Initiate immediately upon admission
• Monitor for ≥24-48 hours to capture paroxysmal arrhythmias 5
• Specifically look for:
  • Paroxysmal AV block (most common in RBBB + syncope) 2, 3
  • Ventricular tachycardia (especially if structural heart disease present) 2, 3
  • Atrial fibrillation with rapid ventricular response
  • Sinus pauses >3 seconds

Transthoracic echocardiography (Class IIa, urgent) 1, 5:

• Assess severity of mitral regurgitation (may have progressed)
• Evaluate left ventricular ejection fraction
• Rule out other structural abnormalities (aortic stenosis, hypertrophic cardiomyopathy)
• Assess right ventricular size and function
• Measure pulmonary artery pressure

Phase II: Electrophysiological Study (If Telemetry Non-Diagnostic)

EPS is indicated when initial monitoring does not reveal a diagnosis 2, 3, 4:

• Diagnostic yield in RBBB + syncope: 42-57% 2, 3
• Most common finding: Inducible paroxysmal AV block (found in 75-84% of positive studies) 2, 3
• HV interval ≥60 ms is a strong predictor of recurrent syncope and progression to complete heart block (HR 3.58) 4
• Bifascicular block predicts recurrence (HR 4.16) 4
• Programmed ventricular stimulation to assess for inducible VT (especially if LVEF reduced or prior MI) 3

EPS findings that mandate pacemaker implantation 2, 3:

• HV interval ≥70 ms
• Inducible infra-Hisian block during atrial pacing
• Inducible sustained ventricular tachycardia (may require ICD instead)

Phase III: Implantable Loop Recorder (If EPS Non-Diagnostic)

ILR insertion (Class IIa) 1, 2:

• Diagnostic yield: 34-52% in patients with BBB and unexplained syncope after negative EPS 2, 3
• Median time to diagnosis of paroxysmal AV block: 97 days (interquartile range 60-117 days) 2
• Continue monitoring until diagnosis or battery depletion
• Most common finding: Paroxysmal AV block (77% of positive ILR studies in BBB patients) 2

Targeted Laboratory Testing

Order only based on specific clinical suspicion (Class III for routine comprehensive panels) 1, 5:

Reasonable targeted tests 1, 5:

• Complete blood count: If anemia suspected (hematocrit <30% is high-risk feature)
• Comprehensive metabolic panel: Assess electrolytes (hypokalemia, hypomagnesemia can prolong QT), renal function (affects medication dosing)
• Magnesium and phosphate: Especially if on diuretics or PPI therapy
• Troponin: If chest pain or ischemic ECG changes present
• BNP: Uncertain utility even when cardiac cause suspected 1

Tests NOT indicated 1, 5:

• Brain CT/MRI (yield 0.24-1% without focal neurological signs)
• EEG (yield 0.7% without seizure features)
• Carotid ultrasound (yield 0.5% without focal neurological deficits)

Management Algorithm Based on Findings

If Paroxysmal AV Block Diagnosed (Most Likely)

Permanent pacemaker implantation (Class I) 2, 3, 4:

• Dual-chamber pacemaker is standard
• Reduces syncope recurrence by >90% 3
• Implant even if asymptomatic periods of AV block documented on monitoring

If Ventricular Tachycardia Diagnosed

Risk stratification for ICD 2, 3:

• VT in setting of structural heart disease (mitral regurgitation) warrants ICD consideration
• If LVEF <35%, ICD is Class I indication
• If LVEF ≥35% but inducible sustained VT on EPS, ICD is Class IIa

If Carotid Sinus Hypersensitivity Diagnosed

Dual-chamber pacemaker (Class I if cardioinhibitory response) 1:

• Indicated if asystole >3 seconds during carotid sinus massage reproduces symptoms
• Less effective for vasodepressor component

If Orthostatic Hypotension Diagnosed

Non-pharmacological measures first 1:

• Review and reduce antihypertensive medications
• Increase sodium and fluid intake (unless contraindicated by heart failure)
• Physical counterpressure maneuvers (leg crossing, squatting)
• Compression stockings
• Consider midodrine or fludrocortisone if refractory

Common Pitfalls to Avoid

• Discharging without cardiac monitoring: RBBB + syncope has 18-33% one-year mortality if cardiac cause missed 1
• Assuming vasovagal syncope: Absence of prodromal symptoms in elderly patient with RBBB strongly argues against reflex mechanism 1, 5
• Ordering brain imaging without focal signs: Yield <1% and delays appropriate cardiac work-up 1, 5
• Relying solely on Holter monitoring: Paroxysmal AV block may not occur within 24-48 hours; median time to diagnosis on ILR is 97 days 2
• Missing medication-induced orthostatic hypotension: Antihypertensives are common contributors in elderly patients 1, 5
• Overlooking progression of mitral regurgitation: Severe MR can cause low cardiac output and syncope, especially with arrhythmias 1
• Failing to assess HV interval on EPS: HV ≥60 ms predicts 3.6-fold increased risk of recurrent syncope 4

Disposition and Follow-Up

Hospital admission required (Class I) 1:

• Continuous telemetry monitoring ≥24-48 hours
• Urgent echocardiography
• Cardiology consultation for EPS consideration if monitoring non-diagnostic
• Geriatric medicine consultation given age >75 years and multimorbidity 1

Outpatient follow-up after discharge 3:

• Cardiology within 1-2 weeks if pacemaker/ICD implanted
• Repeat echocardiography in 3-6 months to reassess mitral regurgitation
• Medication reconciliation to minimize orthostatic risk
• Fall risk assessment and home safety evaluation

Prognosis with appropriate management 3:

• Systematic diagnostic approach achieves 82.7% diagnostic yield
• Pacemaker implantation reduces syncope recurrence by >90%
• 6% mortality at 19-month follow-up in treated patients (primarily non-arrhythmic deaths)