A cine-derived RV coupling ratio tracked iron load and heart failure in thalassaemia

Design

Cross-sectional multicentre cardiac MRI study (E-MIOT)

Population

1154 patients with transfusion-dependent thalassaemia and 167 healthy controls, Italy

Primary outcome

RV–pulmonary arterial coupling and its associations, including heart failure

Effect

RVPAc 0.68 vs 0.59 in controls; independently associated with heart failure, OR 3.99 (P 0.049)

Right ventricular–pulmonary arterial coupling (RVPAc) summarises how well the right ventricle copes with its afterload. Here it was calculated simply, as RV end-systolic volume index divided by RV stroke volume index, from the standard cine images every cardiac MRI already acquires. The Italian E-MIOT network applied it to 1154 consecutive patients with transfusion-dependent thalassaemia and 167 matched controls.

RVPAc was higher in thalassaemia than in controls (0.68 vs 0.59). Within the thalassaemia group it rose with serum ferritin, myocardial iron overload and liver iron concentration, fell with pre-transfusion haemoglobin, and was associated with junctional late gadolinium enhancement. In the multivariable model, higher RVPAc was independently associated with heart failure (OR 3.99, P 0.049).

India carries one of the world's largest burdens of transfusion-dependent thalassaemia, and T2* MRI for cardiac iron is increasingly available in its referral centres. Adding a ratio that needs no extra sequence costs nothing and may pick up right-sided strain before ejection fraction falls. The heart failure association is cross-sectional and only just significant, so treat it as a marker to report, not a threshold to act on.

• Calculate RV end-systolic volume index ÷ RV stroke volume index on every thalassaemia cardiac MRI; it needs no extra sequence.
• Report RVPAc alongside myocardial T2* and biventricular ejection fraction.
• Share a raised ratio with the haematologist alongside T2* and liver iron for context; it is not validated as a trigger to change chelation or transfusion.
• Look for junctional late gadolinium enhancement, which accompanied higher RVPAc.
• Do not use RVPAc alone to diagnose heart failure; the association is cross-sectional.

Why it matters

It gives an early right-heart marker from images already acquired, in a disease common in Indian practice.

Don't overread it

Cross-sectional data with a borderline P value; it does not show RVPAc predicts future heart failure.

The statistics, in plain English

An odds ratio of 3.99 with P = 0.049 sits right at the conventional threshold for significance, so the true association could be much weaker. Cross-sectional means heart failure and the ratio were measured at the same time; the ratio may reflect heart failure rather than precede it.

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