IJCS | Volume 31, Nº2, March / April 2018

146 Teixeira et al. Gas Analysis in the 6-MinuteWalkTest in HFNEF Int J Cardiovasc Sci. 2018;31(2)143-151 Original Article Most patients (70.8%) used beta-blockers. The profile of the medications used by the patients showed the usual therapeutic approach for hypertension: beta‑blockers, angiotensin-converting enzyme inhibitors (25.0%) or angiotensin receptor blockers (54.1%), calcium channel blockers (37.5%), thiazides (29.1%), and vasodilators (48.5%). A stratification of the patients according to the results of the CEPT and following the classification by Weber 17 showed a higher percentage of patients categorized as class B (30.4%). The patients had a mean E/E' of 15.9 ± 4.3, which fulfilled one of the criteria for diagnosis of HFNEF. 11 The mean walked distance was 419.2 ± 76.5 meters during the 6MWT1 and 446.2 ± 67.7 meters during the 6MWT2, with a significant difference between both groups (p = 0.002). Table 2 shows the maximum values of the variables obtained in the 6MWT2 and in the CPET. There was no difference between the maximum respiratory quotient (RQ) values of the two tests, and their maximum values were greater than 1.0. The results showed increased values at the end of the 6MWT2 (1.04), and of 22 patients who underwent the 6MWT2, 11 had an RQ ≥ 1.0 (50% of the group). Of these 11 patients, 7 obtained an RQ ≥ 1.10 (31.8% of the sample). Since BP measurement during the 6MWT was not feasible, BP was only measured in the baseline condition and immediately after the 6MWT. Considering that prior spirometry was not performed, other ventilatory parameters were not assessed. The longitudinal analysis of theHRduring the 6MWT2 showed that the group reached stable HR values after the second minute of the 6MWT2 (T3). The maximum HR Table 2 – Maximum variables obtained in the 6-minute walk test (6MWT) and the cardiopulmonary exercise test (CPET) (n = 22) Mean values - 6MWTversus CPET 6MWT SD CPET SD p < 0.05 Max SBP 187.04 26.60 215.3 27.4 0.002 Max DBP 97.80 13.7 104.1 16.0 0.09 Max DP 20951 5497 27524 6130 0.0004 CircPot 2533 957 3462 1266 0.002 Max HR 110.9 18.1 125.4 19.6 0.004 HR1Rec 23.1 10.1 17.2 10.1 0.035 ChronI 0.42 0.2 0.57 0.1 0.002 O 2 pulse 10.5 3.6 10.5 3.5 0.95 Max RQ 1.06 0.24 1.08 0.09 0.47 VE/VCO 2 slope 22.3 4.8 23.2 4.4 0.10 VP 8.31 1.92 9.59 2.11 0.0002 Peak VO 2 (mL.kg -1 . min -1 ) 13.8 4.1 15.9 5.4 0.025 T1/2 61.4 16.5 111.2 25.7 0.0001 OUES 1.26 0.74 1.34 0.59 0.10 AT VO 2 11.76 3.79 Max SBP: maximum systolic blood pressure; Max DBP: maximum diastolic blood pressure; Max DP: maximum double product; CircPot: circulatory power; Max HR: maximum heart rate; HR1Rec: heart rate in the first minute of recovery; ChronoI: chronotropic index; O 2  pulse: oxygen pulse (mL.kg -1 .min -1 /bpm); Max RQ: maximum respiratory quotient; VE/VCO 2 slope: ventilation minute to carbon dioxide production ratio; VP: ventilatory power; peak VO 2 (mL.kg -1 . min -1 ): oxygen consumption peak; T1/2: time (in seconds) of the recovery kinetics of oxygen consumption up to half of the value of peak effort; OUES: oxygen uptake efficiency slope; AT: anaerobic threshold; 6MWT2: second 6-minute walk test; CPET: cardiopulmonary exercise test; SD: standard deviation. All heart rate values are represented in beats per minute.