Pulmonary 99mTc-HMDP uptake correlates with restrictive ventilatory defects and abnormal lung reactance in transthyretin cardiac amyloidosis patients

Methods

We prospectively enrolled 20 patients with biopsy-proven ATTRv cardiac amyloidosis and 20 control subjects. Cardiac involvement was confirmed by echocardiography and nuclear imaging using 99mTc-HMDP. Semi-quantitative analysis of the heart, rib and lung retention was assessed using a simple region of interest technique.

Pulmonary function was evaluation by the means of whole-body plethysmography, diffusing capacity of the lung for carbon monoxide, forced oscillation technique and cardiopulmonary exercise testing. Results: Pulmonary tracer uptake estimated by lung to rib retention ratio was higher in ATTRv amyloidosis patients compared with control subjects: median 0.62 (0.55–0.69) vs 0.51 (0.46–0.60); p=0.014. Analysis of relation between lung 99mTc-HMDP retention and pulmonary function parameters shown statistically significant correlations with total lung volume (% predicted), lung reactance (Xrs 5Hz) and peak VO2, suggesting total lung capacity restriction impaired elastic properties of the lung and poor aerobic capacity.

Conclusion: Our study suggests that some grade of pulmonary retention of 99mTc-HMDP may occur in patients with cardiac ATTRv amyloidosis, which can elicit deleterious effects on patient’s lung function and aerobic capacity.