Abstract 17535: Incremental Risk Stratification for Diabetic Patients Undergoing Nuclear Exercise Stress Testing by Exercise Capacity, % Heart-Rate Reserve Achieved, and Heart-Rate Recovery
Introduction: Diabetes mellitus (DM) and Exercise (Ex) capacity (EC), chronotropic incompetence, measured by the % heart rate (HR) reserve achieved (%HR-reserve), and abnormal HR-recovery are known predictors of all-cause mortality (ACM). We examined the prognostic relationship of these three Ex variables for predicting ACM in diabetic patients (pts) undergoing Ex myocardial perfusion SPECT (MPS).
Methods: We studied 11,218 pts with no valvular disease and not on beta-blockers who underwent Ex MPS and were followed up for ACM for 3.2 ± 2.2 yrs. EC ≤ 7 METS was considered low. For %HR-reserve [(peak HR - rest HR) x 100/(220-age-rest HR)], <80% was defined as low. HR-recovery (peak HR - recovery HR at 2 min), ≤ 22 was considered abnormal. Summed stress scores (SSS) were calculated using a 20-segment, 5-point MPS model. SSS≥4 was considered abnormal. Pts were categorized into 8 groups based on DM status (yes or no), SSS abnormality, and number of abnormal Ex variables (0-1 vs. 2-3).
Results: There were 1223 patients with DM. 445 patients died in the entire study. SSS, %HR-reserve, HR-recovery, EC, and DM status were all independent predictors of ACM (p<0.01). For both DM and non-DM pts, within each SSS category (Figure 1), pts with 2-3 Ex variable abnormalities were at increased ACM risk compared to pts with 0-1 Ex variable abnormality (p≤ 0.05). In pts with SSS<4, annualized ACM for DM vs non-DM pts was 1.2% vs 0.5% (p=0.0002) in those with 0-1 Ex abnormalities, and 3.3% vs 2.0% (p=0.04) in pts with 2-3 Ex abnormalities. For pts with SSS≥4, presence of DM did not further risk stratify for ACM (p>0.05). DM and non-DM pts had significant increase in annualized ACM with addition of Ex abnormalities in normal and abnormal SSS groups (all p≤ 0.05).
Conclusion: In both DM and non-DM pts undergoing MPS, exercise variables of EC, %HR-reserve, and HR-recovery improve risk stratification for ACM. The presence of diabetes increases the risk of ACM for pts with normal MPS, but not for pts with abnormal MPS.
Author Disclosures: V.Y. Parikh: None. B. Arbit: None. B. Azarbal: None. S. Hayes: None. H. Gransar: None. D.S. Berman: None.
- © 2014 by American Heart Association, Inc.