UC San Diego

To investigate the association between analyses of submaximal treadmill exercise test (TMT) and long-term myocardial ischemia (Mis) and silent Mis in community-dwelling older adults, 898 Rancho Bernardo Study participants (mean age 55 years) without coronary heart disease underwent TMT and were followed up to 27 years. The main outcome measures are incidence of Mis and silent Mis. During follow-up, 97 Mis and 103 silent Mis events occurred. We measured ST change, inability to achieve target heart rate, abnormal heart rate recovery (HRR), and chronotropic incompetence (ChI). Each parameter was a significant predictor for Mis and silent Mis. An integrated scoring model was based on these 4 parameters and defined as sum of numbers of abnormal parameters. After multiple adjustments, an integrated scoring model independently predicted Mis and silent Mis. The incidence rates of abnormalities of parameters are 36.5% for 1 abnormality, 9.1% for 2 abnormalities, and 2.0% for 3 or 4 abnormalities. Compared with those with normal results, participants with 1 or 2 abnormalities had significantly increased risk for Mis (hazard ratio [HR] 1.79 or 2.34, respectively) and silent Mis (HR 1.80 or 2.64, respectively). Participants with 3 or more positive findings showed an even greater risk for Mis (HR 7.96 [3.02 to 21.00]) and silent Mis (HR 3.22 [0.76 to 13.60]). In conclusion, ST change, ChI, abnormal HRR, inability to achieve target heart rate, and integrated scoring model of TMT were independent predictors of long-term Mis and silent Mis in an asymptomatic middle-aged population. Management of ChI or abnormal HRR in an asymptomatic population may prevent future ischemic heart disease and thus improve the quality of life.