2.1

Study design and population

The study was an observational, noninterventional, retrospective, open, monocentric study from January 2012 to July 2013 comparing 2 groups: subjects with and without vitamin D deficiency. Patients already taking vitamin D supplements or with osteoarticular limitations were excluded. Eligible participants were recruited from a CVR unit in Rangueil Hospital in Toulouse. The protocol was approved by the local ethical committee and all subjects gave their informed consent to participate.

2.2

Exercise program

All patients performed a 20-session CVR program, 4 sessions per week. Each session included 40 min of aerobic exercise on a cycloergometer or treadmill continuously monitored, under medical supervision and followed by muscle strengthening supervised by a physiotherapist. Exercise intensity was determined according to the heart rate of the aerobic ventilation threshold during an initial test of maximal exercise capacity. Intensity was increased progressively according to the patient’s tolerance.

2.3

Assessment of outcomes

All patients underwent echocardiography before beginning CVR with left ventricular ejection fraction (LVEF) measurement to evaluate heart failure prevalence (LVEF < 45%). LVEF was calculated as the percentage ratio of the difference between end-diastolic and end-systolic volume to the end-diastolic volume according to the Simpson biplane method . 25OHD level was assessed in a cohort of 131 patients admitted to CVR. 25OHD level in blood samples was assessed before any vitamin D supplementation. The threshold of vitamin D deficiency was 20 ng/ml according to the literature .

Primary endpoints were parameters of physical fitness (6MWD, Pmax) collected at the beginning and end of CVR. Gain in performance was defined as the difference between the initial and the last measurement. 6MWD was measured then calculated in % predicted according to age, gender, height and weight with the equation [7.57 × height (cm)]−[5.02 × age (years)]−[1.76 × weight (kg)]−309 for men, [2.11 × tall (cm)]−[5.78 × age (years)]−[2.29 × weight (kg)] + 667 for women. Ambulatory patients on the first day of CVR underwent functional capacity evaluation by the 6MWD test repeated once. Tests were performed on a flat, straight, indoor 25 m course under physiotherapist supervision. Additionally, patients were measured for maximal exercise capacity on a cycloergometer (JAEGER ER 900) 2 days before CVR, beginning at 20 W with a 10 W increase every minute until maximum performance . Reasons for stopping a test were electrocardiographic modifications (severe ST segment depression > 3 mm or frequent ventricular extrasystoles), increase in blood pressure (systolic > 260 mm Hg, diastolic > 130 mm Hg), or symptoms (severe fatigue, chest pain, dyspnoea, or dizziness) .

At the end of the 20 sessions of CVR, patients performed a final 6MWD test and a final exercise test on the cycloergometer. Evaluations were performed under the same conditions: by same examiner and on the same cycloergometer.

2.4

Statistical analysis

Data were analyzed by use of SPSS 15 (SPSS Inc., Chicago, IL, USA). Normality was assessed by the Kolmogorov-Smirnov test. Data are described as mean ± SD for quantitative data and median (interquartile range) for qualitative data. We compared initial characteristics between vitamin D-deficient and nondeficient patients by Student’s t test for normally distributed variables and Wilcoxon-Mann-Whitney test for nonnormally distributed variables. Proportions were compared by chi-square test or Fisher’s exact test. P < 0.05 was considered statistically significant.

2.1

Study design and population

The study was an observational, noninterventional, retrospective, open, monocentric study from January 2012 to July 2013 comparing 2 groups: subjects with and without vitamin D deficiency. Patients already taking vitamin D supplements or with osteoarticular limitations were excluded. Eligible participants were recruited from a CVR unit in Rangueil Hospital in Toulouse. The protocol was approved by the local ethical committee and all subjects gave their informed consent to participate.

2.2

Exercise program

All patients performed a 20-session CVR program, 4 sessions per week. Each session included 40 min of aerobic exercise on a cycloergometer or treadmill continuously monitored, under medical supervision and followed by muscle strengthening supervised by a physiotherapist. Exercise intensity was determined according to the heart rate of the aerobic ventilation threshold during an initial test of maximal exercise capacity. Intensity was increased progressively according to the patient’s tolerance.

2.3

Assessment of outcomes

All patients underwent echocardiography before beginning CVR with left ventricular ejection fraction (LVEF) measurement to evaluate heart failure prevalence (LVEF < 45%). LVEF was calculated as the percentage ratio of the difference between end-diastolic and end-systolic volume to the end-diastolic volume according to the Simpson biplane method . 25OHD level was assessed in a cohort of 131 patients admitted to CVR. 25OHD level in blood samples was assessed before any vitamin D supplementation. The threshold of vitamin D deficiency was 20 ng/ml according to the literature .

Primary endpoints were parameters of physical fitness (6MWD, Pmax) collected at the beginning and end of CVR. Gain in performance was defined as the difference between the initial and the last measurement. 6MWD was measured then calculated in % predicted according to age, gender, height and weight with the equation [7.57 × height (cm)]−[5.02 × age (years)]−[1.76 × weight (kg)]−309 for men, [2.11 × tall (cm)]−[5.78 × age (years)]−[2.29 × weight (kg)] + 667 for women. Ambulatory patients on the first day of CVR underwent functional capacity evaluation by the 6MWD test repeated once. Tests were performed on a flat, straight, indoor 25 m course under physiotherapist supervision. Additionally, patients were measured for maximal exercise capacity on a cycloergometer (JAEGER ER 900) 2 days before CVR, beginning at 20 W with a 10 W increase every minute until maximum performance . Reasons for stopping a test were electrocardiographic modifications (severe ST segment depression > 3 mm or frequent ventricular extrasystoles), increase in blood pressure (systolic > 260 mm Hg, diastolic > 130 mm Hg), or symptoms (severe fatigue, chest pain, dyspnoea, or dizziness) .

At the end of the 20 sessions of CVR, patients performed a final 6MWD test and a final exercise test on the cycloergometer. Evaluations were performed under the same conditions: by same examiner and on the same cycloergometer.

2.4

Statistical analysis

Data were analyzed by use of SPSS 15 (SPSS Inc., Chicago, IL, USA). Normality was assessed by the Kolmogorov-Smirnov test. Data are described as mean ± SD for quantitative data and median (interquartile range) for qualitative data. We compared initial characteristics between vitamin D-deficient and nondeficient patients by Student’s t test for normally distributed variables and Wilcoxon-Mann-Whitney test for nonnormally distributed variables. Proportions were compared by chi-square test or Fisher’s exact test. P < 0.05 was considered statistically significant.