Association of Summed Rest Score on Technetium-99m Sestamibi With Exercise Capacity and Incident Adverse Outcomes in Hospitalized Patients With Nonischemic Cardiomyopathy: A Retrospective Analysis.
Mima H, Sera F, et al. • Journal of the American Heart Association • 2026
Decreased myocardial 99mTc-MIBI uptake, measured by summed rest score, was associated with impaired exercise capacity and adverse outcomes in patients with nonischemic cardiomyopathy, suggesting that myocardial injury assessment using 99mTc-MIBI scintigraphy may provide prognostic information complementary to exercise capacity.
Key Findings
Results
Patients with nonischemic cardiomyopathy and impaired exercise capacity had significantly higher summed rest scores than those with preserved exercise capacity.
74 of 182 patients (41%) had percentage of predicted peak oxygen consumption (PPVO2) ≤60%, defining exercise capacity impairment
Patients with PPVO2 ≤60% had a median SRS of 12 versus 8 in those with PPVO2 >60% (P<0.001)
Mean patient age was 51.4±14.0 years; 27% were female; all had left ventricular ejection fraction <50%
Study population was retrospectively analyzed from 2016 to 2023
Results
Higher summed rest score remained independently associated with impaired exercise capacity after adjustment for relevant clinical covariates.
The association between higher SRS and PPVO2 ≤60% persisted after adjusting for brain natriuretic peptide level, left ventricular ejection fraction, and heart failure duration
This indicates the relationship between decreased 99mTc-MIBI uptake and exercise impairment is independent of other established markers of heart failure severity
The analysis included 182 patients with nonischemic cardiomyopathy
Results
Higher summed rest score was independently associated with the composite outcome of all-cause death, ventricular assist device implantation, or heart transplantation.
23 patients (13%) experienced the composite adverse outcome over a median follow-up of 807 days
Higher SRS was associated with composite outcomes after adjusting for PPVO2 ≤60%
This suggests SRS provides prognostic information beyond that captured by exercise capacity alone
Results
Patients with both high SRS and low PPVO2 had the highest incidence of adverse events among four groups stratified by SRS and exercise capacity.
Patients were stratified into 4 groups using a median SRS of 9 and PPVO2 threshold of 60%
The group with high SRS (≥9) and low PPVO2 (≤60%) had the highest incidence of composite adverse outcomes
This four-group stratification demonstrated an additive prognostic value of combining myocardial uptake assessment with exercise capacity measurement
Methods
99mTc-MIBI scintigraphy with summed rest score evaluation was used to assess myocardial uptake as a marker of myocardial injury in nonischemic cardiomyopathy.
All 182 patients underwent both 99mTc-MIBI scintigraphy and cardiopulmonary exercise testing
Myocardial uptake of 99mTc-MIBI was quantified using the summed rest score (SRS)
Exercise capacity was assessed by percentage of predicted peak oxygen consumption (PPVO2), with ≤60% defining impairment
The study design was retrospective, covering patients hospitalized from 2016 to 2023
What This Means
This research suggests that a nuclear imaging test called technetium-99m sestamibi (99mTc-MIBI) scintigraphy, which measures how well heart muscle cells take up a radioactive tracer, can provide useful information about how well patients with a type of heart failure called nonischemic cardiomyopathy can exercise and how likely they are to experience serious health events. In 182 hospitalized patients studied over about two years on average, those with lower tracer uptake in the heart (reflected by higher 'summed rest scores') were significantly more likely to have poor exercise capacity, and they also had higher rates of death, needing a heart pump device, or requiring a heart transplant.
Importantly, the link between poor tracer uptake and worse outcomes remained even after accounting for other well-known indicators of heart failure severity, such as BNP levels and heart function measured by echocardiogram. Patients who had both poor tracer uptake and poor exercise capacity had the worst outcomes of all four groups studied, suggesting these two tests capture different but complementary aspects of disease severity.
This research suggests that measuring how much of this tracer the heart muscle absorbs at rest could help doctors better identify which patients with nonischemic cardiomyopathy are at highest risk for serious complications, potentially beyond what standard tests like exercise testing alone can reveal. However, as a retrospective study from a single center, further research would be needed to confirm these findings in broader populations.
Mima H, Sera F, Ohtani T, Akazawa Y, Konishi S, Oka T, et al.. (2026). Association of Summed Rest Score on Technetium-99m Sestamibi With Exercise Capacity and Incident Adverse Outcomes in Hospitalized Patients With Nonischemic Cardiomyopathy: A Retrospective Analysis.. Journal of the American Heart Association. https://doi.org/10.1161/JAHA.126.050214