Adenosine with low-level treadmill exercise is preferred due to superior images and favorable side-effect profile. Surprisingly, little data exists on the hemodynamic effects of additional exercise on adenosine infusion in largely sedentary patients. First Pass Radionuclide Angiography (FPRNA) can simultaneously evaluate both ventricles, and pulmonary function at rest and at peak stress using well-validated non-invasive hemodynamic parameters. We used adenosine testing with and without exercise to evaluate consecutive patients presenting with dyspnea to determine the hemodynamic effects of the additional exercise.
Adenosine was infused at 140 ug/kg/min for 6 minutes while sitting in a chair or walking on a treadmill (1.0 mph, 0% grade). Rest and stress FPRNA were obtained after 15-45 millicurie of sestamibi. Imaging was performed with Sim-400 multicrystal camera.
60 patients (60% female) with mean age 66.2 years were evaluated. 33 patients (55%) exercised (+EX) and 27 patients did not (-EX). Baseline variables were similar in both groups except age, cardiac index, and pulmonary mean transit time (PMTT). Adenosine infusion clearly changes most of the parameters measured (Table 1Table 1.
Univariate comparison of hemodynamic parameters in patients with and without exerciseHemodynamic Variable (Change from rest to exercise)Without Walk (N=27)With Walk (N=33)Test of SignificanceCardiac output –mean (SD)1.06 (0.39)3.15 (0.35)t –4.01, df 58, P < 0.001Cardiac index –mean (SD)0.51 (0.20)1.54 (0.17)t –3.92, df 58, P < 0.001Time to peak flow –mean (SD)0.74 (12.06)- 37.70 (11.87)t 2.25, df 58, P=0.03Peak flow rate–mean (SD)0.10 (0.09)0.93 (0.18)t –3.82, df 58, P < 0.001Pulmonary mean transit time –mean (SD)- 0.80 (0.42)- 1.27 (0.23)t 1.04, df 58, P=0.30). Compared to -EX group, +EX patients had significant augmentation (rest compared to stress) in cardiac output (P< 0.001) and cardiac index (P< 0.001). The addition of exercise significantly improved diastolic function due to increased peak filling rate (P < 0.001) and shortened time to peak filling (P < 0.05) in the +EX group. These effects of exercise remained significant in multiple regression models (Table 2Table 2.
Multivariate comparison of hemodynamic parameters in patients with and without exerciseDependent Variable (Change from rest to exercise)Exercise vs No Exercise GroupsVariables ControlledCardiac outputP=0.002Age,P= 0.06Cardiac indexP=0.03Age, P= 0.06 Cardiac index at rest, P=0.001Time to peak flowP=0.01Age, P=0.18Peak flow rateP=0.003Age, P=0.07pulmonary mean transit timeP=0.004Age, P=0.36 PMTT, P<0.001) that controlled for significant baseline differences in age, cardiac index, and pulmonary mean transit time. When controlling for significant difference in PMTT between the groups at rest, the change in PMTT was significantly different between the groups.
Adenosine infusion alone has significant effects on non-invasive hemodynamic parameters measured by FPRNA. Additional low-level exercise results in improved images and significantly augments many functional parameters increasing the test’s utility.
FPRNA is becoming the favored test to assess cardiovascular function in patients with dyspnea. Adenosine infusion and exercise provide additive benefits.
N. Tripathi, None.