Cardiac Amyloidosis Diagnostic Pathway

The non-biopsy ATTR algorithm, gated on the monoclonal screen, with cited reasoning at every branch

Evidence ABC#tool#cardiology#amyloid#decision

High-yield mode — key points, high-yield facts, tables & quizzes only. Toggle off for full text.

Work a patient through the multisociety non-biopsy pathway for transthyretin (ATTR) cardiac amyloidosis. The monoclonal-protein screen is a hard gate — a positive or absent screen changes the answer before the scan is even interpreted. When the screen is negative, the tool applies the Perugini grade, SPECT confirmation, and H/CL ratio to reach one of four verdicts, each with graded citations, the genuine points of divergence, the differential, and the next steps. It states what the evidence supports for a population — a proposal for discussion, not a written directive.

Clinical / echo–CMR suspicion of infiltration

Monoclonal-protein screen — SPEP + UPEP + immunofixation + serum free light chains

Bone-tracer scan (PYP / DPD / HMDP) — Perugini grade

SPECT confirms uptake is myocardial (not blood pool / bone)

H/CL ratio (optional)

Verdict

—

Copy the verdict + basis as text.

The monoclonal screen is the cardinal rule: AL amyloidosis can also take up bone tracer, so a positive scan is only ATTR when a monoclonal protein has been excluded. Bone-tracer imaging alone never diagnoses AL. Not a written directive.

Evidence & sources

BGillmore JD, et al. Circulation 2016;133:2404–2412 (n=1217): grade 2–3 uptake + negative monoclonal screen >99% specific/PPV for ATTR.

BMultisociety practice points (ASNC/AHA/ASE/EANM/SNMMI/SCMR) — SPECT mandatory, monoclonal screen required, H/CL thresholds.

AATTR-ACT — Maurer MS, et al. N Engl J Med 2018: tafamidis improved outcomes in ATTR cardiomyopathy (accurate diagnosis is actionable).

CPerugini E, et al. J Am Coll Cardiol 2005;46:1076–1084 — 0–3 visual grading scale. ↗

BESC 2023 cardiomyopathy guidance — diagnostic algorithm integrating monoclonal screen and bone scintigraphy.