IM1.15-18 | Heart Failure Investigations — Summary & Reflection

KEY TAKEAWAYS

Investigation of heart failure follows a systematic sequence:

1. Initial bundle (all patients): 12-lead ECG, CXR, BNP/NT-proBNP, bloods (FBC, renal, LFT, TFT, glucose, lipids), urine dipstick.

2. ECG key findings: LVH (Sokolow-Lyon >35 mm), AF (absent P, irregular; calculate CHA₂DS₂-VASc for anticoagulation), LBBB (QRS ≥120 ms, broad R in lateral leads) with LVEF ≤35% and QRS ≥150 ms → CRT eligibility, Q waves → prior MI/ischaemic aetiology.

3. CXR findings by severity: upper lobe venous diversion → early LHF; Kerley B lines → interstitial oedema; bat-wing perihilar shadowing → acute pulmonary oedema; pleural effusion, cardiomegaly (CTR >0.5).

4. BNP thresholds: <35 pg/mL (NT-proBNP <125) makes HF unlikely; >100 pg/mL (NT-proBNP >300) confirms; serial measurement guides diuretic titration.

5. Echocardiography: Classifies HF — HFrEF (LVEF ≤40%), HFmrEF (41–49%), HFpEF (≥50%). Valvular severity: severe AS (AVA ≤1.0 cm², mean gradient ≥40 mmHg); severe MS (MVA <1.0 cm², Wilkins ≤8 → PMBV); severe MR (ERO ≥0.40 cm²). Diastolic function: E/e' >14 → elevated filling pressures.

6. Specialised investigations: Exercise testing → peak VO₂ for transplant listing, inducible ischaemia; Nuclear MPI → reversible (viable) vs fixed (infarcted) defects → guides revascularisation; Coronary angiography → ischaemic aetiology assessment, pre-operative evaluation.

Key valvular intervention thresholds: Symptomatic severe VHD always warrants intervention. Asymptomatic severe VHD with LVEF ≤50–55% (MR/AR) or ≤50% (AS) also warrants intervention.

REFLECT

Consider the journey from a single complaint of breathlessness to a fully classified, aetiologically defined heart failure with a clear management plan. Each investigation in this module answered a specific question — BNP confirmed the diagnosis, ECG revealed AF and LBBB, CXR quantified the degree of congestion, and echocardiography defined the LVEF and identified the valvular lesion. No single test did all of this; it was the synthesis of findings that created the complete picture. Reflect on your own clinical reasoning process: when you see a patient with dyspnoea, do you order tests in a structured sequence with a hypothesis at each step, or do you order a panel of tests simultaneously hoping for an answer to emerge? The sequential, hypothesis-driven approach conserves resources, minimises patient anxiety, and develops your clinical reasoning skills more effectively than a scatter-gun panel. How will you apply this sequence in your next bedside encounter with a breathless patient?