Abstract 2778: Results of 10-year Follow-Up Analysis: Heart Rate Response To Adenosine Stress is an Independent Predictor of Long-Term Outcome In Patients Undergoing Myocardial Perfusion SPECT
Introduction. An abnormal heart rate (HR) response (Abnl-HRR) to adenosine (Adeno) stress, defined as a low peak/rest HR ratio during gated myocardial perfusion SPECT (MPS), is an effective marker of cardiac mortality and sudden death during short-term follow-up (<3 yrs). However, value of Abnl-HRR in predicting long-term (≥10 yr) survival is virtually unknown. We evaluated the ability of Abnl-HRR to independently predict all-cause mortality (ACM) long after Adeno-MPS testing.
Methods. We identified 4,122 pts (50% women, age 71±11 yrs) who underwent Adeno-MPS and then followed for 12±2 yrs. Pts were categorized as follows: normal (perfusion defect<5%), mildly (5–10%), moderately (10–20%) and severely (>20%) abnormal MPS. Multivariable Cox proportional hazards analysis was deployed to assess the prognostic value of clinical/MPS variables in predicting ACM. Abnl-HRR to Adeno-stress was defined as peak/rest HR ratio<1.12 (Abidov et al, 2003).
Results. There were 1882 ACM events with an annualized rate of 4.6%. MPS was a powerful predictor of long-term survival; however, within each MPS category, presence of Abnl-HRR revealed a subset of pts at additional increased risk of ACM (Figure⇓; *p<0.001 vs. Normal-HRR). By multivariable analysis, Abnl-HRR was found to be an independent and incremental predictor of long-term ACM (p<0.001), adding to other significant clinical/MPS predictors in the model.
Conclusions. Within each Adeno-stress MPS category, presence of an Abnl-HRR identifies a subset of pts with additional increased long-term risk of ACM. 10-year survival analysis demonstrates that Abnl-HRR is an independent and incremental multivariable predictor of ACM.