Arm exercise stress perfusion imaging predicts clinical outcome

Abstract

Treadmill exercise capacity in resting metabolic equivalents (METs) and stress hemodynamic, electrocardiographic (ECG), and myocardial perfusion imaging (MPI) responses are independently predictive of adverse clinical events. However, limited data exist for arm ergometer stress testing (AXT) in patients who cannot perform leg exercise because of lower extremity disabilities. We sought to determine the extent to which AXT METs, hemodynamic, ECG, and MPI responses to arm exercise add independent incremental value to demographic and clinical variables for prediction of all-cause mortality, myocardial infarction (MI), or late coronary revascularization, individually or as a composite. A prospective cohort of 186 patients aged 64 ± 10 (SD) yr, unable to perform lower extremity exercise, underwent AXT MPI for clinical reasons between 1997 and 2002, and were followed for 62 ± 23 mo, to an endpoint of death or 12/31/2006. Average annual rates were 5.4% for mortality, 2.2% for MI, 2.5% for late coronary revascularization, and 8.0% for combined events. After adjustment for age and clinical variables, AXT METs [P < 0.05; hazard ratio (HR) = 0.59; confidence interval (CI) = 0.35-0.84] and abnormal MPI (P < 0.01; HR = 2.48; CI = 2.15-2.81) were independently predictive of mortality. A positive AXT ECG (P < 0.05; HR = 2.61; CI = 2.13-3.10) was predictive of MI. Death and MI combined were prognosticated by METs (P < 0.05; HR = 0.63; CI = 0.41-0.85), MPI (P < 0.05; HR = 1.77; CI = 1.49-2.05), and a positive AXT ECG (P < 0.05; HR = 1.86; CI = 1.55-2.17). In conclusion, for high risk older patients who cannot perform leg exercise because of lower extremity disabilities, AXT METs are as important as MPI for prediction of mortality alone and death and MI combined, and a positive AXT ECG prognosticates MI alone and death and MI combined.

Fig. 1.

Kaplan-Meier survival curve for arm exercise capacity and myocardial perfusion imaging (MPI) results. METs, resting metabolic equivalents.

Fig. 2.

Kaplan-Meier myocardial infarction (MI)-free survival curve for arm exercise capacity and MPI results.

Fig. 3.

Incremental prognostic value for prediction of death.

Fig. 4.

Incremental prognostic value for prediction of death and MI combined.