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Kidney Week

Abstract: PO2512

Utility of the 6-Minute Walk Test in Coronary Artery Disease Screening Before Kidney Transplant

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Cheng, Xingxing S., Stanford University School of Medicine, Stanford, California, United States
  • Watford, Daniel J., Stanford University School of Medicine, Stanford, California, United States
  • Arashi, Hiroyuki, Stanford University School of Medicine, Stanford, California, United States
  • Tan, Jane C., Stanford University School of Medicine, Stanford, California, United States
  • Fearon, William F., Stanford University School of Medicine, Stanford, California, United States
Background

Coronary artery disease (CAD) screening is a cornerstone of kidney transplant (KTx) evaluation, but existing approaches result in excess testing and low intervention rate. We hypothesize that aerobic performance, based on a simple office test (the 6-minute walk test, 6MWT), may help risk stratify KTx candidates.

Methods

We performed 6MWT in waitlisted patients who were nearing KTx. Results were used for frailty counselling and not for cardiac evaluation. CAD screening was done according to our center protocol: invasive angiogram for patients with long-standing diabetes mellitus (DM) and non-invasive testing for other patients with risk factors and at the evaluating transplant nephrologist’s discretion. We used subdistribution Cox regression and time-dependent receiver operator curve to evaluate time to CAD event (revascularization, myocardial infarction, waitlist removal for CAD, or cardiac death), treating waitlist removal for non-CAD and non-cardiac death as competing events.

Results

Of the 360 patients, 200 and 161 patients had 6MWT results <400 meters and >=400 meters (~4 metabolic equivalents), respectively. Patients with lower 6MWT results were older (59±10 vs 50±12 years) and more likely to be female (54% vs 34%), have DM (61% vs 33%) or known atherosclerotic disease (44% vs 22%), and have had prior cardiac evaluation (72% vs 61%). They were also more likely to exhibit cardiac symptom during 6MWT (36% vs 6%) and more likely to be censored due to waitlist removal for non-CAD reasons (follow-up 391±337 vs 541±277 days). 6MWT was not associated with CAD event (subdistribution hazard ratio 1.00 [0.90-1.10], 1-year area under the curve [AUC] 0.54). 196 patients had invasive (52%) or non-invasive (48%) CAD testing within 6 months of 6MWT: 6MWT did not predict the CAD test result (odds ratio 0.96 [0.81-1.14], AUC 0.54). Of the 94 patients who had concurrent non-invasive CAD testing, the 1-year AUC of 6MWT, symptom (at rest or during 6MWT), AST guidelines, or non-invasive testing for CAD event were 0.64, 0.52, 0.46 and 0.66 respectively.

Conclusion

The 6MWT did not perform better in risk stratification for CAD events compared to a symptom- or risk factor-based approach.

Funding

  • Private Foundation Support