MUNICH – The big news in the field of heart failure at the annual congress of the European Society of Cardiology concerned an obscure form of the disease traditionally considered rare: transthyretin amyloid cardiomyopathy (TAC).
It turns out that TAC is far more common than previously recognized; it can now be diagnosed and staged noninvasively; and – most important of all – there is for the first time an effective disease-modifying treatment in the form of a novel oral drug called tafamidis, as demonstrated in the Transthyretin Amyloidosis Cardiomyopathy Clinical Trial (ATTR-ACT) presented at the meeting.
“This is the first phase 3 trial that can offer a chance for people with a terrible, severe disease. And within the last year, while the trial was being conducted, it became clear that this disease is much more underdiagnosed than rare,” said Claudio Rapezzi, MD, ATTR-ACT principal investigator and director of the school of cardiovascular diseases at the University of Bologna, Italy.
ATTR-ACT participants randomized to tafamidis showed significant reductions in all-cause mortality and cardiovascular hospitalizations, compared with placebo-treated controls at 30 months follow-up. They also experienced significantly lesser declines in both quality of life as reflected in Kansas City Cardiomyopathy Questionnaire scores and in physical function as captured in 6-minute walk distance.
Designated discussant Jacob George, MD, was over the moon regarding the results.
“This is a pioneering, game-changing trial that is likely to transform the way we diagnose and treat patients with cardiac amyloidosis,” said Dr. George of Kaplan Medical Center in Rehovot, Israel.
“We’re now in an era that, to my opinion, any patient with nonischemic unexplained heart failure should be screened for the presence of amyloidosis because, first, we now know how to prognosticate these patients, and second, we can offer them a real disease-modifying agent,” he added.
An underdiagnosed disease
Transthyretin amyloid cardiomyopathy occurs when transthyretin, a transport protein, becomes destabilized and misfolds, promoting deposition of amyloid fibrils in the myocardium. This results in progressive ventricular wall thickening and stiffness, manifest as restrictive cardiomyopathy and progressive heart failure. The cause of transthyretin destabilization can be either autosomal dominant inheritance of any of more than 100 pathogenic mutations in the transthyretin gene identified to date or a spontaneous wild type protein.
Think of TAC as a sort of dementia of the heart. As Dr. George noted, the cardiac disease bears “remarkable similarities” to Alzheimer’s disease, with both conditions entailing extracellular deposition of amyloid.
In the heritable form of TAC, patients typically present with heart failure symptoms at about age 50-55, while the wild type form becomes symptomatic much later at a mean age of about 75. Average survival from time of diagnosis is only about 3 years.
Recent studies from multiple centers have reported that the prevalence of TAC was 16% in patients undergoing transcatheter aortic valve replacement for severe aortic stenosis, 13% among patients with heart failure with preserved ejection fraction, and 5% in patients who had been presumed to have hypertrophic cardiomyopathy: So, not a rare condition.
“In our clinic, vast and surprising numbers of patients with unexplained nonischemic heart failure are scan positive [for TAC],” according to Dr. George.