Abstract
Background
In nonischemic cardiomyopathy, the clinical relevance of decreased resting myocardial technetium‐99m sestamibi (
99m
Tc‐MIBI) uptake regarding exercise capacity and clinical outcomes remains incompletely understood. We investigated whether decreased
99m
Tc‐MIBI uptake is associated with impaired exercise capacity and adverse clinical outcomes in nonischemic cardiomyopathy.
Methods
We retrospectively analyzed 182 patients (mean age 51.4±14.0 years; 27% female) with nonischemic cardiomyopathy and left ventricular ejection fraction 99m
Tc‐MIBI scintigraphy and cardiopulmonary exercise testing from 2016 to 2023. Myocardial uptake of
99m
Tc‐MIBI was evaluated using the summed rest score (SRS). Exercise capacity was assessed by percentage of predicted peak oxygen consumption (PPVO
2
), with ≤60% defining impairment.
Results
Seventy‐four patients (41%) had PPVO
2
≤60% and higher SRS (median: 12 versus 8;
P
2
≤60% after adjustment for relevant clinical covariates, including brain natriuretic peptide level, left ventricular ejection fraction, and heart failure duration. Over a median follow‐up of 807 days, 23 patients (13%) experienced the composite outcome of all‐cause death, ventricular assist device implantation, or heart transplantation. Higher SRS was associated with composite outcomes after adjusting for PPVO
2
≤60%. Among the 4 groups stratified by median SRS of 9 and PPVO
2
of 60%, patients with high SRS and low PPVO
2
had the highest incidence of adverse events.
Conclusions
Decreased myocardial
99m
Tc‐MIBI uptake was associated with impaired exercise capacity and adverse outcomes in patients with nonischemic cardiomyopathy. Our findings suggest that myocardial injury assessment using
99m
Tc‐MIBI scintigraphy may provide prognostic information complementary to exercise capacity.