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TOPLINE:

Cardiopulmonary exercise testing may be useful in characterizing distinct patterns of functional impairment in patients with transthyretin amyloidosis (ATTR), a multisystem, life-threatening disease resulting from the deposition of transthyretin amyloid fibrils.

METHODOLOGY:

• The study used cardiopulmonary exercise testing in 506 patients with ATTR amyloidosis under the care of the National Amyloidosis Centre, London, England, to characterize the spectrum of functional capacity, characterize functional decline with respect to amyloidotic burden, and assess prognosis.

TAKEAWAY:

• Results showed that impairment of functional capacity was highly prevalent in all patients, with each disease phenotype demonstrating distinctive patterns of functional impairment.
• Peak oxygen consumption, oxygen pulse, and ventilatory efficiency were impaired in cardiac phenotypes, while chronotropic incompetence and exercise oscillatory ventilation were prevalent across all phenotypes.
• Worsening amyloid burden was associated with a decline in multiple cardiopulmonary exercise testing parameters, although chronotropic response and exercise oscillatory ventilation remained abnormal irrespective of amyloid burden.
• Peak oxygen consumption and peak systolic blood pressure were independently associated with prognosis.

IN PRACTICE:

The researchers noted that impaired physical performance is a hallmark of ATTR amyloidosis, with the 6-minute walk test being increasingly used as primary and secondary endpoints in recent clinical trials, but this test only provides a simple estimation of exercise tolerance, without insights into the functional phenotype.

Cardiopulmonary exercise testing is the gold standard for the evaluation of putative mechanisms that underlie exercise intolerance in heart failure, and indices derived from this testing have repeatedly emerged as strong predictors of mortality.

The findings of the current study suggest that cardiopulmonary exercise testing offers a more comprehensive method of evaluating functional capacity in patients with ATTR amyloidosis compared with existing measures for future prospective studies.

SOURCE:

The study, led by Rishi K. Patel, MBBS, National Amyloidosis Centre, University College London, England, was published online in JAMA Cardiology on March 6.

LIMITATIONS:

The study used simple cardiopulmonary exercise testing, and additional approaches would be required to measure possible lung amyloid infiltration and additional pathways linked to peripheral, mitochondrial, and neuropathic function. The prognostic significance of cardiopulmonary exercise testing variables has been demonstrated for all-cause mortality as the outcome, but the association of these variables with heart failure hospitalization could provide additional and clinically relevant information.

DISCLOSURES:

The study was supported by the British Heart Foundation.