Mitral regurgitation in ATTR cardiomyopathy carries risk at lower thresholds

Design

Multicentre international cohort with derivation and external validation

Population

1,101 patients with newly diagnosed transthyretin amyloid cardiomyopathy

Primary outcome

All-cause death and first heart failure admission

Effect

Composite grading: 21% severe vs ≈12–13% by guideline; HR 1.20 (1.07–1.36) death, 1.21 (1.05–1.38) heart failure admission

An eight-centre international cohort enrolled 1,101 patients with newly diagnosed transthyretin amyloid cardiomyopathy, with a derivation group of 722 and a validation group of 379. Echocardiograms were read blind in a core laboratory. Over a median of about 25 months, 28.5% died and 22.2% were admitted with heart failure.

Risk began to rise at a vena contracta of 3.0 mm, an effective regurgitant orifice area of 0.10 cm², a regurgitant volume of 15 mL or a regurgitant fraction of 20%. High risk began above an orifice area of 0.25 cm², a volume of 38 mL or a fraction of 35% — all well below standard cut-offs. The resulting composite scheme labelled 21% as severe, against about 12–13% with guideline definitions, and it alone stayed predictive after adjustment (HR 1.20 for death, 1.21 for heart failure admission).

The likely reason is the low-flow, restrictive physiology of amyloid, which shrinks regurgitant volumes. This is prognostic work, not a trial of intervention: it tells you who is at risk, not that treating the valve helps.

• Report quantitative mitral regurgitation measures in ATTR cardiomyopathy, not just a visual grade
• Treat moderate-looking regurgitation in amyloid as a marker of higher risk
• Use the finding to sharpen follow-up intensity and heart failure management
• Do not refer for transcatheter mitral repair on these thresholds alone; that question is untested

Why it matters

Standard grading may be under-calling a prognostically important lesion in a disease cardiologists now see far more often.

Don't overread it

These are prognostic thresholds from an observational cohort — they do not show that intervening on the valve improves outcomes.

The statistics, in plain English

A hazard ratio of 1.20 means about 20% higher risk of death at any given time for each step up the composite grade, after adjusting for other factors. Confirming the thresholds in a separate validation cohort makes it less likely they are a quirk of one dataset.

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