Cardio-circulatory exercise response in AL amyloidosis and comparison with hypertrophic cardiomyopathy

Abstract

Cardiopulmonary exercise test (CPET) can help the physician in understanding mechanisms that underlie patients exercise limitation. We aimed to characterize exercise response in AL amyloidosis through CPET and to compare it with hypertrophic sarcomeric cardiomyopathy (HCM). We prospectively included 49 patients: 24 with cardiac amyloidosis (group A), 10 with amyloidosis without cardiac involvement (group B) and 15 HCM (group C). All were clinically stable and underwent clinical examination, ECG, echocardiography, cardiac MRI and CPET. CPET assessed systolic blood pressure (SBP) as well as heart rate (HR) responses, O 2 pulse response, peak VO 2 , circulatory power (SBPxVO 2 ) and VE/VCO 2 slope. The SBP response was 25 mmHg in group A from rest to peak exercise, 19 mmHg in group B and 49 mmHg in group C ( P < 0.05). Circulatory power was 2073 mmHg.mL −1 min _1 in group A, 2620 mmHg.mL −1 min _1 in group B and 4040 mmHg.mL −1 min _1 in group C ( P < 0.05). A chronotropic incompetence was observed in 46% of group A and 44% in group B versus 7% in group C ( P < 0.05). Peak VO 2 was 14 mL.min.Kg −1 in group A, 19 mL.min.Kg −1 in group B and 20 mL.min.Kg −1 in group C ( P < 0.05). The increase of O 2 pulse during exercise was 2 in group A versus 3 in group B and group C ( P < 0.05). The VE/VCO 2 slope was increased in group A compared to group B and C (respectively 40 vs. 31 and 30, P < 0.05). CPET quantifies and specifies determinants of the poor cardio-circulatory response during exercise in AL amyloidosis patients, including decrease of peak VO2 and low circulatory power suggestive of poor exercise inotropic reserve; a chronotropic incompetence that can be related to cardiac dysautonomia and an increase of VE/VCO2 slope suggestive of exercise pulmonary hypertension.