Abstract
Background
A variety of exercise stress testing protocols with various workloads are available. The test protocol is typically selected according to patient's expected exercise performance.
Purpose
We sought to assess whether the choice of the protocol is by itself independently associated with mortality even after adjusting for clinical variables and estimated workload achieved in metabolic equivalents of task (METS).
Methods
In a 25-year stress testing registry spanning from 1991 to 2015, we identified 120,705 patients who underwent 7 different standardized exercise protocols: Bruce, Modified Bruce, Cornell 0%, 5%, and 10%, Naughton, and modified Naughton. The choice of the protocol was dependent on the supervising exercise physiologist, mainly according to patient's expected exercise performance. The primary outcome was all-cause mortality.
Results
Mean age was 53.3±12.5 years and 59% were male. There were 74953 Bruce, 8368 modified Bruce, 2648 Cornell 0%, 9972 Cornell 5%, 20425 Cornell 10% 1226 Naughton, and 3113 modified Naughton protocols. A total of 8426 death occurred over 8.7 years of mean follow-up duration. Table 1 presents the baseline characteristics by protocol. After adjusting for the number of METs, age, gender, hypertension, diabetes, coronary disease, end-stage renal disease, smoking, and statin use, the protocol selected remained predictive of mortality. Figure 1 shows the adjusted HR for death by protocol selected when compared to Bruce.
Baseline characteristics by protocol Variable Bruce (n=74953) Modified Bruce (n=8368) Cornell 0% (n=2648) Cornell 5% (n=9972) Cornell 10% (n=20425) Naughton (n=1226) Modified Naughton (n=3113) Age, mean ± SD 49.4±11.3 61.3±10.3 66.4±11.7 62.5±11.8 57.2±11.5 67.5±9.8 55.5±11.9 Male, % 64.6 51.8 37.8 42.3 51.7 49 66.7 Coronary disease, % 8.7 32.5 31.7 26.7 21.1 49.7 45.6 Diabetes mellitus, % 7.6 16.5 25.3 20 14.2 27.2 26.2 Hypertension, % 41.7 64 85.4 77.9 67.1 82.5 97.5 Smoker, % 40.9 55 50.7 50.9 50.8 56.9 60.6 ESRD, % 0.7 1 3.7 2.4 1.6 2.7 8.1 Mets, mean ± SD 10.3±2.4 7.2±1.7 5.2±1.6 6.7±1.5 8.3±1.9 4.8±1.5 4.6±1.5 Statin use, % 22.4 15.2 41.8 38.3 35.1 19 40.1 ESRD = end-stage renal disease; METS = metabolic equivalents of task.
Adjusted HR by protocol selected
Conclusion
The choice of the stress testing protocol, which is in large part dependent on patient's expected exercise performance is in itself independently associated with mortality even after adjustment for METs achieved and patients' demographics and comorbidities. The choice of the modified-Naughton is associated with the greatest risk of mortality, likely chosen based on limited functional capacity
Late Aminophylline Reversal of Regadenoson Stress Testing in Patients with End Stage Renal Disease
