Compared with placebo, tafamidis was linked to improved long-term survival in patients with transthyretin amyloid cardiomyopathy, according to new data from the ATTR-ACT trial.

As Healio previously reported, in the main results of ATTR-ACT, tafamidis (Vyndamax, Pfizer) reduced risk for all-cause mortality and CV-related hospitalizations in patients with hereditary and wild-type transthyretin amyloid cardiomyopathy at 30 months.

“Transthyretin amyloid cardiomyopathy (ATTR-CM) is an uncommon condition that results in progressive heart failure and severe disability,” Perry Elliott, MBBS, MD, professor of cardiovascular medicine and director of the Centre for Heart Muscle Disease at University College London, told Healio. “Once diagnosed, untreated patients with ATTR-CM have a median survival of approximately 2 to 3.5 years. Vyndaqel/Vyndamax is the first and currently only treatment approved for wild-type and hereditary ATTR-CM. The pivotal ATTR-ACT trial demonstrated that treatment with Vyndaqel/Vyndamax resulted in a significant 30% reduction in all-cause mortality over a 30-month period and can help slow disease progression. The aim of this post hoc, interim analysis was to evaluate the durability of this benefit of Vyndaqel/Vyndamax for ATTR-CM patients.”

Elliott and colleagues enrolled 176 patients from the tafamidis group and 177 patients from the placebo group in a long-term extension study. The tafamidis group continued with its tafamidis (Vyndamax) dose. The placebo group was randomly assigned tafamidis meglumine (Vyndaqel) 80 mg or 20 mg per day, and after a protocol amendment, was transitioned to tafamidis free acid 61 mg, a bioequivalent to tafamidis meglumine 80 mg.

After a median follow-up of 58.5 months in the continuous tafamidis group and 57.1 months in the placebo-to-tafamidis group, the mortality rate was lower in the continuous tafamidis group (44.9% vs. 62.7%; HR = 0.59; 95% CI, 0.44-0.79; P < .001), Elliott and colleagues found.

Mortality rates favored the continuous tafamidis group in patients with hereditary transthyretin amyloidosis (HR = 0.57; 95% CI, 0.33-0.99; P = .05), patients with wild-type transthyretin amyloidosis (HR = 0.61; 95% CI, 0.43-0.87; P = .006), patients with baseline NYHA class I or II HF (HR = 0.56; 95% CI, 0.38-0.82; P = .003) and patients with baseline NYHA class III HF (HR = 0.65; 95% CI, 0.41-1.01; P = .06), according to the researchers.

“The results from this analysis demonstrate that early diagnosis and continued treatment with Vyndaqel/Vyndamax has the potential to significantly extend survival for all patients living with ATTR-CM, regardless of disease severity,” Elliott told Healio.

“In recent years there have been great strides in recognizing the signs and symptoms of ATTR-CM, but ATTR-CM remains underdiagnosed,” he said. “More needs to be done to understand and mitigate the barriers to early diagnosis so that more patients with ATTR-CM can benefit from treatment before they present with more advanced stages of the condition.”