most patients who undergo surgical repair of tetralogy of fallot ( tof ) have excellent functional outcomes and lead a normal active and social life.1)2)3)4 ) nevertheless , almost all patients have some degree of pulmonary regurgitation ( pr ) as a result of right ventricular outflow tract reconstruction;1)5 ) and consequently , the chronic volume overload may lead to right ventricle ( rv ) dilation , biventricular dysfunction , heart failure symptoms , arrhythmias , and sudden death.6)7)8)9 ) pulmonary valve replacement ( pvr ) is commonly undertaken to avoid these adverse outcomes . since patients often express symptoms late , assessment of objective exercise tolerance by cardiopulmonary exercise ( cpex ) testing is a potential tool for the optimal timing of pvr in asymptomatic patients.10 ) magnetic resonance imaging ( mri ) , a gold standard for evaluating rv volumes and function , can also be used to decide the indications for pvr.11 ) the aim of this study was to investigate the effect of pvr on exercise capacity and determine cpex parameters - associated with improvement in rv function among patients who underwent cpex testing and mri in pre and post pvr period . a total of 245 patients who underwent pvr for chronic pr after repair of tof from january 1998 to october 2015 in sejong general hospital were retrospectively analyzed . the patients who underwent cpex testing before and after pvr were included only if respiratory exchange ratio ( rer ) was 1.05 in cpex testing before and after pvr , in order to exclude biased data from patients who stopped exercising for non - cardiovascular reasons.12 ) the following cpex parameters were obtained : peak oxygen uptake ( vo2peak ) , percentage of predicted vo2peak , slope of respiratory minute volume to co2 production ( ve / vco2 ) , anaerobic threshold ( vo2at ) ; in addition , the following mri parameters were analyzed : right ventricular ejection fraction ( rvef ) ( % ) , right ventricular end diastolic volume index ( rv edvi ) , right ventricular end systolic volume index ( rv esvi ) . clinical data such as gender , age at study onset , age at pvr , body surface area ( bsa ) and clinical status were obtained by review of medical records . cpex testing was performed using modified bruce protocol on true one 2400 ( parvo medics , salt lake city , ut , usa ) . heart rate , blood pressure , and oxygen saturation were monitored for the duration of the test . vo2peak ( ml / kg / min ) was defined as the highest respiratory oxygen uptake ( vo2 ) achieved by the subject during the maximal exercise . vo2 was determined by cardiac output and the difference of oxygen content between arterial and venous blood by the fick equation.13 ) values for vo2peak ( ml / kg / min ) were indexed to body weight . vo2peak ( ml / kg / min ) was often presented as a percentage of predicted value , predicted vo2peak ( % ) , which was determined by age , gender , body height , and body weight.14 ) ve / vco2 ratio indicates the number of liters of air breathed to eliminate 1 liter of co2.13 ) vo2at ( ml / kg / min ) was defined as the vo2 during exercise at which the blood lactate level began to rise ( anaerobic threshold by lactate measurements).15 ) studies were performed using a 1.5-t gyroscanintera cv system ( philips medical systems , best , the netherlands ) . multiphase acquisition was obtained using steady - state free precession pulse sequence in 2- and 4-chamber planes . from these images , 10 to 12 contiguous short - axis slabs perpendicular to the long axis of the left ventricle were obtained ( slice thickness 6 to 8 mm ; inter slice gap 0 to 2 mm ) . ventricular volumetric analysis was performed using extended mr workspace software ( philips medical systems , best , the netherlands ) . stroke volume was calculated by deducting end - systolic volume from end - diastolic volume ; and ejection fraction was calculated as percent stroke volume divided by end - diastolic volume . all continuous variables were expressed as mean or medianstandard deviation . paired student 's t - test was used to compare cpex and mri parameters with normal distribution before and after pvr . patients were divided into 2 groups based on improvement in vo2peak after pvr . the unpaired 2-sample t - test was used to compare the baseline and changes of variables between the two groups . kolmogorov - smirniv test and shapiro - wilk test were used to assess the normality of distribution . correlations between cpex and mri parameters were tested using pearson 's test for normally distributed variables . chicago , il , usa ) was used for statistical analysis , and p<0.05 was considered statistically significant . a total of 245 patients who underwent pvr for chronic pr after repair of tof from january 1998 to october 2015 in sejong general hospital were retrospectively analyzed . the patients who underwent cpex testing before and after pvr were included only if respiratory exchange ratio ( rer ) was 1.05 in cpex testing before and after pvr , in order to exclude biased data from patients who stopped exercising for non - cardiovascular reasons.12 ) the following cpex parameters were obtained : peak oxygen uptake ( vo2peak ) , percentage of predicted vo2peak , slope of respiratory minute volume to co2 production ( ve / vco2 ) , anaerobic threshold ( vo2at ) ; in addition , the following mri parameters were analyzed : right ventricular ejection fraction ( rvef ) ( % ) , right ventricular end diastolic volume index ( rv edvi ) , right ventricular end systolic volume index ( rv esvi ) . clinical data such as gender , age at study onset , age at pvr , body surface area ( bsa ) and clinical status were obtained by review of medical records . cpex testing was performed using modified bruce protocol on true one 2400 ( parvo medics , salt lake city , ut , usa ) . heart rate , blood pressure , and oxygen saturation were monitored for the duration of the test . vo2peak ( ml / kg / min ) was defined as the highest respiratory oxygen uptake ( vo2 ) achieved by the subject during the maximal exercise . vo2 was determined by cardiac output and the difference of oxygen content between arterial and venous blood by the fick equation.13 ) values for vo2peak ( ml / kg / min ) were indexed to body weight . vo2peak ( ml / kg / min ) was often presented as a percentage of predicted value , predicted vo2peak ( % ) , which was determined by age , gender , body height , and body weight.14 ) ve / vco2 ratio indicates the number of liters of air breathed to eliminate 1 liter of co2.13 ) vo2at ( ml / kg / min ) was defined as the vo2 during exercise at which the blood lactate level began to rise ( anaerobic threshold by lactate measurements).15 ) studies were performed using a 1.5-t gyroscanintera cv system ( philips medical systems , best , the netherlands ) . multiphase acquisition was obtained using steady - state free precession pulse sequence in 2- and 4-chamber planes . from these images , 10 to 12 contiguous short - axis slabs perpendicular to the long axis of the left ventricle were obtained ( slice thickness 6 to 8 mm ; inter slice gap 0 to 2 mm ) . ventricular volumetric analysis was performed using extended mr workspace software ( philips medical systems , best , the netherlands ) . stroke volume was calculated by deducting end - systolic volume from end - diastolic volume ; and ejection fraction was calculated as percent stroke volume divided by end - diastolic volume . all continuous variables were expressed as mean or medianstandard deviation . paired student 's t - test was used to compare cpex and mri parameters with normal distribution before and after pvr . patients were divided into 2 groups based on improvement in vo2peak after pvr . the unpaired 2-sample t - test kolmogorov - smirniv test and shapiro - wilk test were used to assess the normality of distribution . correlations between cpex and mri parameters were tested using pearson 's test for normally distributed variables . chicago , il , usa ) was used for statistical analysis , and p<0.05 was considered statistically significant . of the 245 patients , preoperative mri was performed in 166 and postoperative mri in 77 ; and preoperative cpex in 88 patients and postoperative cpex in 76 patients . among the patients who underwent all 4 examinations , only 28 patients showed rer 1.05 and were included in the final analysis . the mean age at study was 24.215.42 years old and the mean age at pvr was 19.955.01 years old . the median duration from pre pvr cpex testing to pvr was 1.0 months ( range : 0.0 - 39.0 ) and the median duration from pvr to post pvr cpex testing was 15.0 months ( range : 4.0 - 56.0 ) . the median duration from pre pvr mri to pvr was 3.5 months ( range : 0.0 - 22.0 ) and the median duration from pvr to post pvr mri was 11.5 months ( range : 3.0 - 53.0 ) ( table 1 ) . pre pvr cpex testing and mri mentioned above refer to cpex testing and mri performed before pvr . also , post pvr cpex testing and mri mentioned above refer to cpex testing and mri performed after pvr . vo2peak ( ml / kg / min ) was changed from 30.084.84 to 29.835.16 ( p=0.803 ) and predicted vo2peak ( % ) was changed from 69.3914.36 to 67.7110.84 ( p=0.500 ) . in addition , ve / vco2 ratio was changed from 27.343.86 to 26.774.70 ( p=0.559 ) and vo2at ( ml / kg / min ) was changed from 23.823.61 to 22.784.43 ( p=0.194 ) . in conclusion , cpex parameters showed no significant changes after pvr ( table 2 ) . on the other hand , rv edvi ( ml / m ) was changed from 174.3924.64 to 121.0424.89 ( p<0.001 ) and rv esvi ( ml / m ) was changed from 92.2121.07 to 63.3918.95 ( p<0.001 ) . however , rvef ( % ) was changed from 47.745.89 to 48.457.59 ( p=0.623 ) , without significance ( table 2 ) . despite the absence of significant changes in cpex parameters after pvr , we analyzed the characteristics of the patients who showed improved exercise capacity after pvr . if post pvr vo2peak of patients were increased compared to pre pvr vo2peak ( pre pvr vo2peak < post pvr vo2peak ) , we designated them as group 1 . conversely , if post pvr vo2peak of patients were decreased compared to pre pvr vo2peak ( pre pvr vo2peak > post pvr vo2peak ) , we designated them as group 2 . however , the exercise capacities of the patients in group 1 improved significantly ; the mean vo2at ( ml / kg / min ) improved from 24.15 to 25.38 ( p=0.051 ) , the mean vo2peak ( ml / kg / min ) from 28.53 to 33.09 ( p=0.001 ) ( fig . on the other hand , the exercise capacities of patients in group 2 decreased significantly ; the mean vo2at ( ml / kg / min ) decreased from 23.58 to 20.83 ( p=0.030 ) , the mean vo2peak ( ml / kg / min ) from 31.24 to 27.39 ( p<0.001 ) ( fig . 2 ) . baseline predicted vo2peak ( % ) value was significantly lower in patients in group 1 ( 60.8310.28 ) , as compared to group 2 ( 75.8113.83 ) ( p=0.003 ) ( fig . however , baseline vo2peak , ve / vco2 ratio , vo2at were not significantly lower in patients belonging to group 1 than group 2 ( 28.535.18 vs. 31.244.38 , p=0.159 , 27.433.46 vs.27.274.24 , p=0.914 , 24.154.19 vs. 23.583.22 , p=0.697 , respectively ) . in addition , the changes of vo2peak , predicted vo2peak ( % ) , vo2at in patients belonging to group 1 were significantly higher than group 2 ( 4.563.60 vs. -3.852.51 , p<0.001 ; 10.177.63 vs. -10.568.03 , p<0.001 ; 1.221.94 vs. -2.744.58 , p=0.009 , respectively ) ( table 4 ) ( fig . group - wise comparisons between baseline mri parameters and changes in mri parameters after pvr indicated that baseline rv edvi and rv esvi values were lower and baseline rvef ( % ) was higher in patients belonging to group 1 than group 2 , without significance ( 165.9216.35 vs. 180.7528.22 , p=0.093 ; 86.9216.87 vs. 96.1923.47 , p=0.235 ; 48.336.13 vs. 47.305.87 , p=0.657 , respectively ) . also , the absolute value of changes of rv edvi , rv esvi , rvef ( % ) in group 1 patients were lower than group 2 patients , without statistical significance . ( 47.1720.32 vs. 58.0022.36 , p=0.193 ; 24.6714.73 vs. 31.9416.48 , p=0.231 ; 0.538.81 vs. 1.646.54 , p=0.481 , respectively ) ( table 5 ) . we analyzed the correlations between rvef ( % ) on mri and cpex parameters ( vo2peak , predicted vo2peak ( % ) , ve / vco2 , vo2at ) in each group . we first analyzed the correlations between baseline rvef ( % ) and baseline cpex parameters ( vo2peak , predicted vo2peak ( % ) , ve / vco2 , vo2at ) in each group . as a result , we found negative correlation between baseline rvef ( % ) and baseline vo2peak ( r=0.590 , p=0.043 ) , negative correlation between baseline rvef ( % ) and baseline vo2at ( r=0.693 , p=0.012 ) in patients belonging to group 1 ; on the other hand , patients belonging to group 2 showed no significant correlations . subsequently , we analyzed the relationships between the changes of rvef ( % ) and the changes of cpex parameters ( vo2peak , predicted vo2peak ( % ) , ve / vco2 , vo2at ) in each group . the results indicated that patients belonging to group 1 showed a positive correlation between the change of rvef ( % ) and the change of vo2at ( r=0.733 , p=0.007 ) ( fig . 5 ) ; whereas , patients belonging to group 2 showed a negative correlation between the change of rvef ( % ) and the change of predicted vo2peak ( % ) ( r=0.575 , p=0.020 ) ( table 6 . ) of the 245 patients , preoperative mri was performed in 166 and postoperative mri in 77 ; and preoperative cpex in 88 patients and postoperative cpex in 76 patients . among the patients who underwent all 4 examinations , only 28 patients showed rer 1.05 and were included in the final analysis . the mean age at study was 24.215.42 years old and the mean age at pvr was 19.955.01 years old . the median duration from pre pvr cpex testing to pvr was 1.0 months ( range : 0.0 - 39.0 ) and the median duration from pvr to post pvr cpex testing was 15.0 months ( range : 4.0 - 56.0 ) . the median duration from pre pvr mri to pvr was 3.5 months ( range : 0.0 - 22.0 ) and the median duration from pvr to post pvr mri was 11.5 months ( range : 3.0 - 53.0 ) ( table 1 ) . pre pvr cpex testing and mri mentioned above refer to cpex testing and mri performed before pvr . also , post pvr cpex testing and mri mentioned above refer to cpex testing and mri performed after pvr . vo2peak ( ml / kg / min ) was changed from 30.084.84 to 29.835.16 ( p=0.803 ) and predicted vo2peak ( % ) was changed from 69.3914.36 to 67.7110.84 ( p=0.500 ) . in addition , ve / vco2 ratio was changed from 27.343.86 to 26.774.70 ( p=0.559 ) and vo2at ( ml / kg / min ) was changed from 23.823.61 to 22.784.43 ( p=0.194 ) . in conclusion , cpex parameters showed no significant changes after pvr ( table 2 ) . on the other hand , rv edvi ( ml / m ) was changed from 174.3924.64 to 121.0424.89 ( p<0.001 ) and rv esvi ( ml / m ) was changed from 92.2121.07 to 63.3918.95 ( p<0.001 ) . however , rvef ( % ) was changed from 47.745.89 to 48.457.59 ( p=0.623 ) , without significance ( table 2 ) . despite the absence of significant changes in cpex parameters after pvr , we analyzed the characteristics of the patients who showed improved exercise capacity after pvr . if post pvr vo2peak of patients were increased compared to pre pvr vo2peak ( pre pvr vo2peak < post pvr vo2peak ) , we designated them as group 1 . conversely , if post pvr vo2peak of patients were decreased compared to pre pvr vo2peak ( pre pvr vo2peak > post pvr vo2peak ) , we designated them as group 2 . however , the exercise capacities of the patients in group 1 improved significantly ; the mean vo2at ( ml / kg / min ) improved from 24.15 to 25.38 ( p=0.051 ) , the mean vo2peak ( ml / kg / min ) from 28.53 to 33.09 ( p=0.001 ) ( fig . on the other hand , the exercise capacities of patients in group 2 decreased significantly ; the mean vo2at ( ml / kg / min ) decreased from 23.58 to 20.83 ( p=0.030 ) , the mean vo2peak ( ml / kg / min ) from 31.24 to 27.39 ( p<0.001 ) ( fig . 2 ) . baseline predicted vo2peak ( % ) value was significantly lower in patients in group 1 ( 60.8310.28 ) , as compared to group 2 ( 75.8113.83 ) ( p=0.003 ) ( fig . however , baseline vo2peak , ve / vco2 ratio , vo2at were not significantly lower in patients belonging to group 1 than group 2 ( 28.535.18 vs. 31.244.38 , p=0.159 , 27.433.46 vs.27.274.24 , p=0.914 , 24.154.19 vs. 23.583.22 , p=0.697 , respectively ) . in addition , the changes of vo2peak , predicted vo2peak ( % ) , vo2at in patients belonging to group 1 were significantly higher than group 2 ( 4.563.60 vs. -3.852.51 , p<0.001 ; 10.177.63 vs. -10.568.03 , p<0.001 ; 1.221.94 vs. -2.744.58 , p=0.009 , respectively ) ( table 4 ) ( fig . group - wise comparisons between baseline mri parameters and changes in mri parameters after pvr indicated that baseline rv edvi and rv esvi values were lower and baseline rvef ( % ) was higher in patients belonging to group 1 than group 2 , without significance ( 165.9216.35 vs. 180.7528.22 , p=0.093 ; 86.9216.87 vs. 96.1923.47 , p=0.235 ; 48.336.13 vs. 47.305.87 , p=0.657 , respectively ) . also , the absolute value of changes of rv edvi , rv esvi , rvef ( % ) in group 1 patients were lower than group 2 patients , without statistical significance . ( 47.1720.32 vs. 58.0022.36 , p=0.193 ; 24.6714.73 vs. 31.9416.48 , p=0.231 ; 0.538.81 vs. 1.646.54 , p=0.481 , respectively ) ( table 5 ) . we analyzed the correlations between rvef ( % ) on mri and cpex parameters ( vo2peak , predicted vo2peak ( % ) , ve / vco2 , vo2at ) in each group . we first analyzed the correlations between baseline rvef ( % ) and baseline cpex parameters ( vo2peak , predicted vo2peak ( % ) , ve / vco2 , vo2at ) in each group . as a result , we found negative correlation between baseline rvef ( % ) and baseline vo2peak ( r=0.590 , p=0.043 ) , negative correlation between baseline rvef ( % ) and baseline vo2at ( r=0.693 , p=0.012 ) in patients belonging to group 1 ; on the other hand , patients belonging to group 2 showed no significant correlations . subsequently , we analyzed the relationships between the changes of rvef ( % ) and the changes of cpex parameters ( vo2peak , predicted vo2peak ( % ) , ve / vco2 , vo2at ) in each group . the results indicated that patients belonging to group 1 showed a positive correlation between the change of rvef ( % ) and the change of vo2at ( r=0.733 , p=0.007 ) ( fig . 5 ) ; whereas , patients belonging to group 2 showed a negative correlation between the change of rvef ( % ) and the change of predicted vo2peak ( % ) ( r=0.575 , p=0.020 ) ( table 6 . ) the detrimental effects of pr after total repair of tof are now widely known , which , has led to earlier pvr , in most instances before overt symptoms.10 ) pvr enables volume unloading of the rv , which may be essential for preserving ventricular function . the hemodynamic effects of pvr are assessed by functional class , volumetric changes and exercise tolerance using mri and cpex parameters . mri is the first imaging modality that provides exact quantification of regurgitated volume and rv ventricular volume and mass.16 ) this mri information might lead to identification of new quantitative indicators for pvr and facilitate the management of these patients.17 ) in addition , a better understanding of the effect of altering different pathologic rv loading conditions on cpex parameters might help to refine the selection criteria and timing of pvr.8 ) in our study , pre pvr cpex parameters ( vo2peak , predicted vo2peak [ % ] , ve / vco2 , vo2at ) showed consistently decreased exercise capacity ( table 2 ) . low vo2peak is likely the consequence of multiple interrelated factors ( ex , rv dysfunction , rv pressure and volume overload ) that act synergistically to impair exercise function.19 ) cpex parameters showed no significant improvement after pvr in our study , which is consistent with the other studies19)20)21 ) that showed no improvement in vo2peak after pvr.22 ) on the other hand , mri revealed reduced volumes of the dilated right ventricle ( rv edvi , rv esvi ) after pvr , but no significant improvement in rvef ( % ) after pvr . however , the pre pvr data may represent an overestimation of the effective ejection fraction , because a regurgitation of the pulmonary or tricuspid valve leads to an increase of the end diastolic volume and therefore , to a higher ejection fraction . corrected rvef was calculated as percent effective rv stroke volume divided by rv end diastolic volume.23 ) although the rv function did not improved statistically by rvef on mri , corrected rvef indicated improvement of rvef , preoperative corrected rvef ( % ) 21.824.51 vs. postoperative corrected rvef ( % ) 39.529.46 ( p<0.001 ) . thus , if the effects of regurgitation on the measurement of ejection fraction are considered , it may lead to improvement in real rv output after valve replacement.16 ) discussion of the many factors that can influence corrected rvef is beyond the scope of this study . although no significant improvement in exercise capacity was detected , we tried to determine the characteristics of the patients who showed improvement in exercise capacity . peak uptake of oxygen ( vo2peak ) is the most commonly used variable to describe aerobic capacity.24 ) so we analyzed the characteristics between the two groups divided by vo2peak value ( i.e. , whether post pvr vo2peak increased or decreased from pre pvr vo2peak ) . the group - wise comparison showed that the exercise capacities in group 1 patients improved statistically . and predicted vo2peak ( % ) was significantly lower in increased group ( group 1 ) than decreased group ( group 2 ) unlike other cpex parameters ( vo2peak , ve / vco2 ratio , vo2at ) . this finding showed the importance of predicted vo2peak ( % ) in evaluating exercise capacity of our patients . in addition , the changes of predicted vo2peak ( % ) were significantly larger in increased group ( group 1 ) than decreased group ( group 2 ) . these findings suggested that patients who had significantly lower pre - pvr predvo2peak ( % ) could improve exercise capacity after pvr . for the relationships between rvef ( % ) and cpex parameters , we found negative correlation between baseline rvef ( % ) and baseline vo2peak ( r=0.590 , p=0.043 ) , the negative correlation between baseline rvef ( % ) and baseline vo2at ( r=0.693 , p=0.012 ) in patients belonging to group 1 . however , if the exercise capacity is decreased despite preserved rv function , we suggest that such patients need pvr for recovery of exercise capacity , however , further study with more data is required . positive correlation occurred between the change of rvef ( % ) and the change of vo2at in patients belonging to group 1 . thus , the change of vo2at is a more sensitive indicator than vo2peak to predict the improvement of rvef ( % ) after pvr ; and the change of rv function using the cpex . vo2peak might be underestimated because of reduced patient motivation , as well as premature termination of exercise by the examiner . vo2at measures the sustainable o2 uptake and is an objective parameter of exercise capacity derived from submaximal exercise testing ; and therefore , independent of these influences.25 ) it corresponds to approximately 70% of the peak oxygen consumption in the symptom - limited maximal exercise and is a simple and noninvasive means for respiratory measurements well before maximal effort.15 ) stevenson reported that vo2at was essentially interchangeable with vo2peak.26 ) the decrease in vo2at is probably caused by earlier onset of anaerobic metabolism due to insufficient blood supply for working muscles , which is a net result of reduced cardiovascular reserve , and reduction in level of physical fitness.27 ) in this case , despite the rise in rvef ( % ) , vo2at can not be increased , contrary to our expectations . on the other hand , training delays blood lactate accumulation during submaximal exercise and these changes are associated with an increase in the vo2at.28 ) in addition , several other factors may play an important role , including skeletal muscle fiber type and motor unit recruitment patterns , glycogen stores , adrenergic stimulation , and skeletal muscle aerobic enzyme content.29 ) therefore , it is possible to detect the increase of vo2at without the change of rvef ( % ) . finally , negative correlation was found between the change of rvef ( % ) and the change of predicted vo2peak ( % ) in patients belonging to group 2 . these findings showed the importance of predicted vo2peak ( % ) in evaluating exercise capacity repeatedly and deterioration of exercise capacity after pvr . therefore , vo2peak is usually expressed as the predicted vo2peak ( % ) in evaluating exercise capacity . the predicted vo2peak ( % ) is the percentage of value which is calculated in consideration of variable factors ( age , gender , body weight , body height ) . therefore , it is very important to regularly determine the predicted vo2peak for evaluating exercise capacity after pvr . underlying pulmonary function abnormalities limit pulmonary gas exchange response,22 ) and ultimately , result in a reduced exercise capacity . the reduction in alveoli number , increased alveolar density , decreased lung volume , and decreased vital capacity have been demonstrated in patients with tof.30 ) the patients with a lower vital capacity are expected to have a lower vo2peak , a lower breathing reserve . thus , in order to increase the accuracy of improved exercise capacity after pvr , it might be helpful to perform cpex testing with pulmonary function test . but , the patients belonging to our study group did not perform the pulmonary function test . in addition , the time intervals between cpex testing and pvr varied among patients . since the point that rv function is restored after pvr may differ in each patient finally , our study was conducted with a retrospective model and a small sample size . despite these limitations , pr after tof repair led to earlier pvr but showed no significant improvement in cpex parameters after pvr , despite significant decreases in rv volume . however , we could determine the characteristics of improved exercise capacity group and worsening exercise capacity group after pvr . baseline predicted vo2peak ( % ) value was significantly lower in patients with significantly improved exercise capacity after pvr than in patients with worsening exercise capacity after pvr . therefore , we confirmed the importance of predicted vo2peak ( % ) in evaluating exercise capacity differentiated from other cpex variables . in addition , the change of rvef ( % ) was positively correlated with the change of vo2at . but in patients with worsening exercise capacity post pvr , the change of rvef ( % ) showed a negative correlation with the change of predicted vo2peak ( % ) . therefore , the change of vo2at and predicted vo2peak ( % ) are sensitive indicators to predict the change of rvef ( % ) after pvr . underlying pulmonary function abnormalities limit pulmonary gas exchange response,22 ) and ultimately , result in a reduced exercise capacity . the reduction in alveoli number , increased alveolar density , decreased lung volume , and decreased vital capacity have been demonstrated in patients with tof.30 ) the patients with a lower vital capacity are expected to have a lower vo2peak , a lower breathing reserve . thus , in order to increase the accuracy of improved exercise capacity after pvr , it might be helpful to perform cpex testing with pulmonary function test . but , the patients belonging to our study group did not perform the pulmonary function test . in addition , the time intervals between cpex testing and pvr varied among patients . since the point that rv function is restored after pvr may differ in each patient finally , our study was conducted with a retrospective model and a small sample size . despite these limitations , pr after tof repair led to earlier pvr but showed no significant improvement in cpex parameters after pvr , despite significant decreases in rv volume . however , we could determine the characteristics of improved exercise capacity group and worsening exercise capacity group after pvr . baseline predicted vo2peak ( % ) value was significantly lower in patients with significantly improved exercise capacity after pvr than in patients with worsening exercise capacity after pvr . therefore , we confirmed the importance of predicted vo2peak ( % ) in evaluating exercise capacity differentiated from other cpex variables . in addition , the change of rvef ( % ) was positively correlated with the change of vo2at . but in patients with worsening exercise capacity post pvr , the change of rvef ( % ) showed a negative correlation with the change of predicted vo2peak ( % ) . therefore , the change of vo2at and predicted vo2peak ( % ) are sensitive indicators to predict the change of rvef ( % ) after pvr .
background and objectivesthe aim of this study was to investigate the effect of pulmonary valve replacement ( pvr ) on exercise capacity and determine cardiopulmonary exercise ( cpex ) parameters associated with improvement in right ventricle ( rv ) function.subjects and methodswe retrospectively analyzed cpex and magnetic resonance imaging parameters in a total of 245 patients who underwent pvr from january 1998 to october 2015 . 
 in addition , we analyzed the characteristics of the patients who showed improved exercise capacity after pvr.resultstwenty-eight patients met the inclusion criteria for the study . 
 cpex parameters after pvr showed no significant changes in all patients . however , baseline predicted peak oxygen uptake ( vo2peak ) ( % ) value was significantly lower in patients with significant improvement in exercise capacity after pvr , as compared to patients who showed decreased exercise capacity after pvr ( 60.8310.28 vs. 75.8113.83 ) ( p=0.003 ) . 
 in addition , patients with improved exercise capacity showed a positive correlation between the change of right ventricular ejection fraction ( rvef ) ( % ) and the change of anaerobic threshold ( r=0.733 , p=0.007 ) ; whereas , patients with decreased exercise capacity showed a negative correlation between the change of rvef ( % ) and the change of predicted vo2peak ( % ) ( r=0.575 , p=0.020).conclusionthe importance of predicted vo2peak ( % ) in evaluating exercise capacity differentiated from other cpex variables . 
 the change of anaerobic threshold and predicted vo2peak ( % ) might be a useful predictor of the change in rv function after pvr .