September 2026 Research Update

This month, studies following people on tafamidis (a transthyretin-stabilizing medicine) made it clearer that prognosis is not explained by the heart findings alone. Across cohorts, higher frailty and certain baseline characteristics separated people with higher versus lower chances of dying during follow-up. This matters because it frames ATTRwt-CM as an illness where overall strength and independence add useful information alongside cardiac test results. [1] [2]

In a French cohort of 410 people treated with tafamidis, those classified as frail had higher mortality than those considered robust (36% vs 24%). Frailty stayed linked to mortality even after accounting for other factors, and areas like needing help at home and reduced functional or motor independence were among the parts of frailty connected to death. In plain terms, how well someone is functioning day to day carried important information about risk in this group. [1]

A much larger pooled analysis (1924 people on tafamidis) showed notable sex differences in who was being treated and what happened during about 1.5 years of follow-up. Women were a small minority, tended to start treatment with worse functional stage, and were more likely to have inherited ATTR rather than wild-type, but men had a higher adjusted risk of death during follow-up. This adds to the picture that ATTR populations are not all the same, and that comparing outcomes without considering sex and ATTR type can be misleading. [2]

For patients and caregivers, these results mainly add understanding about what predicts outcomes while on tafamidis, rather than changing what any one person should do. The most practical message is that measures of independence and need for help at home captured meaningful differences in risk in one large cohort, and sex differences also appeared in a very large treated population. What remains uncertain is how much improving frailty measures would change outcomes, and whether the sex differences reflect biology, differences in diagnosis timing, differences in disease type (wild-type vs inherited), or other factors not fully captured here. [1] [2]

One study this month focused on how the heart's electrical wiring changes over time during tafamidis treatment. The overall pattern was gradual slowing of conduction on ECG over 1 year, with a small number of people needing implanted rhythm devices. The study also explored whether baseline imaging and blood markers could hint at who might see more change, but these signals were not consistent across all analyses. [3]

In 50 people with wild-type ATTR-CM followed for 1 year after starting tafamidis, the average PQ interval and QRS duration increased compared with baseline, meaning conduction through the heart became slower. Of the 60 people originally enrolled, 4 needed a permanent pacemaker during the year (1 of whom later also received cardiac resynchronization therapy); they were left out of the 50-person analysis, which the authors noted may make conduction worsening look milder than it really is. Baseline MRI native T1 and a blood marker of heart injury (hs-cTnT) were reported as predictors in one model, but the study also reported that in a different model those predictors were no longer significant. [3]

For patients, this mainly clarifies that rhythm and conduction changes can still progress over time even while taking tafamidis, at least over 1 year in this cohort. It also adds an early research signal that certain baseline MRI and blood test results might relate to later conduction slowing, but this is not yet firm because the predictors depended on the analysis approach. This does not by itself say what any one person will experience, but it explains why ongoing rhythm tracking is often part of ATTR-CM follow-up in real-world care. [3]

This month strengthened the message that diagnosing wild-type ATTR cardiomyopathy can be challenging for two reasons: it can start outside the heart and it can sometimes evade a single test. Across studies, non-cardiac warning signs often appeared years before diagnosis, a longer wait from the first warning sign to diagnosis was linked to worse survival, and multiple imaging approaches (including repeat testing or different tracers) helped explain why some scans are negative or hard to interpret. For patients, the big picture is that the path to diagnosis is often a process, not a single moment or single scan. [4] [5] [6]

In an Italian multicenter cohort of 208 people (mostly wild-type ATTR-CM), longer time from first warning sign to diagnosis was linked to higher all-cause and cardiovascular mortality. Orthopedic and neurologic issues were reported as some of the earliest signals, often appearing years before diagnosis, while most diagnostic pathways eventually converged through cardiology referral. In plain language, the earlier clues were frequently not classic heart symptoms, and waiting longer to reach an ATTR-CM diagnosis was tied to worse outcomes in this dataset. [4]

Imaging studies also highlighted why results may differ between tests or between centers. A head-to-head comparison of two amyloid PET scans (11C-PiB and 18F-flutemetamol) in 16 people with biopsy-confirmed wild-type ATTR cardiac amyloidosis found strongly similar uptake patterns, supporting the idea that results could be harmonized for multicenter tracking. Separately, a Tc-99m-PYP scan study in 209 people with suspected cardiac amyloidosis reported that liver and spleen tracer uptake did not separate ATTR from non-ATTR, while uptake in the small intestine and colon was higher in ATTRwt-CA, suggesting the scan may show signals outside the heart that are not simply "background" blood activity. [6] [7]

A case report added a practical example of how ATTR-CM can be missed on a first nuclear scan. A man with a donut-shaped pattern on cardiac MRI had an initially negative PYP scan, but a repeat SPECT-enabled PYP scan later showed localized basal uptake consistent with wild-type ATTR-CM; after tafamidis and optimized heart failure therapy, he improved over 3 months. The main point is not that scans are unreliable, but that certain patterns of amyloid distribution may require tailored imaging approaches. [5]

For patients and caregivers, these findings matter most for understanding the diagnostic journey and why it can take time. The cohort study links longer diagnostic delay to higher mortality, which supports the importance of recognizing that problems like carpal tunnel-type orthopedic issues or nerve symptoms may be part of the ATTR story in some people, even before heart symptoms are obvious. The imaging studies mainly matter for the future of more consistent diagnosis and follow-up across hospitals, and they also help explain why a single negative scan may not end the conversation when suspicion remains high. Uncertainty remains about how often the specific imaging pitfalls described occur, and how best to use gut uptake findings from PYP scans in day-to-day care. [4] [6] [7] [5]

This month’s case reports and small case series did not change the overall understanding of ATTRwt-CM, but they illustrated real-world exceptions that can affect diagnosis and management plans. Several reports showed that ATTR can coexist with other common heart problems in older adults, and that imaging results can be misleading when amyloid is distributed in atypical ways. Together, these stories help explain why care often uses more than one test and why treatment timing may depend on the full clinical situation. [8] [9] [10]

One case described an older woman with both severe aortic stenosis and wild-type ATTR cardiomyopathy, managed with transcatheter aortic valve implantation first and tafamidis after recovery, with short-term functional improvement. Another case described an older man with chest pain and elevated troponin despite normal large coronary arteries, where biopsy revealed amyloid mainly blocking small intramural heart vessels and bone scintigraphy was negative; after tafamidis, symptoms and walking distance improved over a year. These reports underline that ATTR can contribute to symptoms through more than one pathway, including valves and small-vessel involvement. [8] [9]

Two reports focused on scan interpretation rather than symptoms alone. In one man treated with tafamidis and heart failure medicines including spironolactone, myocardial PYP tracer uptake decreased while breast uptake increased, attributed to gynecomastia, showing a potential source of confusing "extra" uptake. A separate case series of 10 Afro-Caribbean patients in a safety-net hospital showed that PYP scanning was feasible and positive in all cases, with a mix of wild-type and Val122Ile inherited ATTR among those tested, and a substantial minority needing pacemakers. [10] [11]

For patients, case reports mainly offer context: they show what can happen, not what usually happens. The practical value is understanding that ATTRwt-CM can sit alongside other conditions like aortic stenosis, and that some people can have negative bone scans when amyloid is concentrated in certain areas such as small heart vessels, which is why additional testing is sometimes needed. These reports also highlight that imaging tracers can show uptake outside the heart for reasons unrelated to amyloid in the heart, which can complicate interpretation. Because these are small numbers (sometimes single patients), it is uncertain how common these situations are. [8] [9] [10] [11]

A tissue-based study this month added detail to what the ATTRwt heart looks like at a cellular level. The main finding was that the heart muscle cells showed changes in mitochondria (the cell's energy producers) and reduced ability to generate energy, and these changes lined up more clearly with how thick the heart wall was than with amyloid burden measures. For patients, this supports the idea that symptoms and heart function may reflect more than just the quantity of amyloid deposits. [12]

In biopsies from 52 people with ATTRwt cardiomyopathy, the study reported altered mitochondrial structure and reduced oxidative phosphorylation (energy production). When participants were grouped by heart wall thickness on echocardiography, thicker walls aligned with fewer and smaller mitochondria and lower oxidative function. Measures intended to reflect amyloid load (including MRI extracellular volume and stereology-based amyloid quantification, in subsets) did not show significant relationships with oxidative phosphorylation in this report. [12]

For patients and caregivers, this is mainly background science rather than something used in routine visits right now. It helps clarify why two people with a similar amyloid burden on imaging might still feel different or have different heart performance, because the heart muscle cells themselves may be struggling to make energy. What remains uncertain is whether these mitochondrial findings can be measured without a biopsy, and whether future treatments could target this specific type of cell stress. [12]