Key result
Patients with Val122Ile variant transthyretin amyloid cardiomyopathy had lower peak VO2 (14.4 vs 19.5 mL/kg/min) and blunted heart rate recovery compared with age-matched controls.
Why the study?
Impaired aerobic capacity in cardiac amyloidosis may relate to limited inotropic myocardial reserve and heart rate response, prompting investigation into whether chronotropic incompetence and blunted heart rate recovery are prevalent in mutant transthyretin cardiomyopathy.
Does Val122Ile variant transthyretin amyloid cardiomyopathy cause chronotropic incompetence and blunted heart rate recovery compared to age-matched controls?
Cross-Sectional (n=33)
Does Val122Ile variant transthyretin amyloid cardiomyopathy cause chronotropic incompetence and blunted heart rate recovery compared to age-matched controls?
In Afro-Caribbean patients with Val122Ile ATTRv cardiomyopathy, impaired aerobic capacity is primarily driven by a restrictive cardiac phenotype rather than chronotropic incompetence, though heart rate recovery is blunted.
May indicate clinically relevant functional limitation in Val122Ile ATTR-CM; leaves open prognostic and therapeutic implications.
Background: Impaired aerobic capacity in cardiac amyloidosis patients may be related to limited inotropic myocardial reserve and heart rate (HR) response limiting cardiac output rise. This study sought to investigate whether chronotropic incompetence (CI) and blunted HR recovery would be prevalent in patients with mutant transthyretin (ATTRv) cardiomyopathy.Methods and results: Eighteen ATTRv (Val122Ile) patients (72 ± 8-year) and 15 age-matched controls (73 ± 3-year) were prospectively enrolled. Patients' medical records, pulmonary function and cardiopulmonary exercise testing, including non-invasive cardiac hemodynamics and chronotropic response were studied. Compared with age-matched controls, maximal workload (91 ± 8 vs. 65 ± 20 watts) and peak VO2 (19.5 ± 3.0 vs. 14.4 ± 4.1 mL.kg−1.min−1) were lower in ATTRv patients. Despite reaching similar age-predicted maximal HR, ATTRv patients displayed smaller changes in stroke volume (SV) index relative to change in VO2 (49 ± 26 vs. 67 ± 18%). Adequate chronotropic-metabolic index was prevalent in ATTRv patients. HR recovery, as percent decrease in peak HR at 1 and 3-min, was blunded ATTv patients.Conclusions: In Val122Ile ATTRv patients, chronotropic response was appropriate relative to exercise intensity with only few patients displaying CI. HR response to exercise was further characterised by blunted HR recovery in ATTRv patients suggesting lower parasympathetic activity and greater sympathetic stimulation compared with controls.
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Monfort et al. (2020) conducted a cross-sectional in Mutant transthyretin (ATTRv) cardiomyopathy (n=33). Val122Ile variant transthyretin amyloid cardiomyopathy vs. Age-matched controls was evaluated on Peak VO2 (mL.kg−1.min−1). Patients with Val122Ile variant transthyretin amyloid cardiomyopathy had lower peak VO2 (14.4 vs 19.5 mL/kg/min) and blunted heart rate recovery compared with age-matched controls.
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