Use of a single-item exercise questionnaire predicts prognostic risk among patients undergoing stress PET-MPI

Background: Exercise activity reduces mortality and favorably influences mediators of risk, including myocardial flow reserve (MFR) and chronotropic responsiveness. Comprehensive research regarding the relationship between exercise activity, MFR, and chronotropic response to pharmacological stress, as assessed by heart rate response (HRR) among patients undergoing PET myocardial perfusion imaging (MPI) has not been performed. Thus, we aimed to evaluate the relationship between exercise activity as assessed by a practical single-item questionnaire, MFR and HRR, and longitudinal clinical risk. Methods: We studied outpatients who underwent pharmacological stress rubidium-82. PET-MPI and answered a self-reported one-item exercise activity questionnaire (0–10 scale) at the time of PET-MPI. HRR was calculated by the following equation: (stress HR-rest HR)/rest HR∗100 (%). The primary outcome was death or myocardial infarction. Results: Of 1686 patients, 221 (13%) patients had hard events during our mean follow up of 3.8 years. Patients were divided into four groups: no/minimal exercise (n = 551), low exercise (n = 468), moderate exercise (n = 485), and high exercise (n = 182) based on the questionnaire. MFR and HRR increased with exercise activity in a stepwise manner. By Cox analysis adjusted for clinical and PET-MPI variables including MFR and HRR, exercise activity was independently associated with hard events (HR [95%CI] per activity scale, .95 [.91-.99]; P = .028). Conclusions: Patients with higher exercise activity assessed by a practical single-item questionnaire had higher MFR and HRR. Exercise activity was an independent predictor of hard events in patients undergoing PET-MPI. Because of its ease of use, this single-item questionnaire should be applied among patients undergoing stress MPI.