Heart failure (HF) is a systemic clinical syndrome defined as cardiac dysfunction, which causes inadequate blood supply to meet metabolic needs. One of the most expressive markers of HF is neurologic exacerbation, with expected sympathetic hyperactivation, increased activity of the renin-angiotensin-aldosterone system and elevation of vasopressin levels. These changes compensate the low cardiac output in the onset of ventricular dysfunction ensure a long term high blood perfusion pressure,though aggravate this dysfunction and contributes to the HF progression. There are evidences ofthe therapeutic effects of respiratory exercise techniques for HF patients. However, it demands new data for larger prescription and employment of these kind of exercises. Advanced technologies allowed the elaboration of the application for slow breathing CardioBreath. So far, it requires the possibility of comparison of their effects versus widely validated Inspiratory Muscle Trainig (IMT) on respiratory and cardiovascular outcomes in order to elucidate their specific benefits. In this way compare CardioBreath ® App versus IMT through a crossover randomized clinical trial design may elucidate the response effects of these interventions in these patients.

The impact of pulmonary, ventilatory and cardiovascular impairment in patients with congestive heart failure (CHF) highlights the therapeutic relevance of breathing exercises for these functions. In addition, other benefits such as lowering blood pressure,increased cardiac vagal modulation, improved vascular function and psychosocial handling (anxiety, depression and stress) may be expected. Inspiratory Muscle Training (IMT) and slow yoga breathing are widely endorsed as beneficial by a large amount of evidence. The newly developed app CardioBreath ® is based on a breathing technique of yoga (ujjayi pranayama) through respiratory rates (RR) slower than the user's spontaneous RR, in a set of strategies with pedagogical prescription, guidance and monitoring of this type of exercises. This study aims to compare IMT exercises with those of the CardioBreath ® application on , strength respiratory muscle (manuvacuometry), cardiac vagal modulation (heart rate variability), arterial stiffness (heart rate wave velocity) and diaphragm thickness in CHF patients after their hospital discharge in Institute of Cardiology of Rio Grande do Sul. Methods: Crossover randomized control trial will recruit post-discharge CHF patients who will be evaluated through, Finometer system (HR and BP variability/cardiac vagal modulation), Arterial Stiffness (oscillometric method), for indexes of central arterial pressure, velocity pulse waveform (large artery stiffness) and Aix 75 (small artery stiffness), Respiratory Muscle Strength by Manovacuometry and Diaphragm Thickness by ultrasound. Patients will be randomized to two orders of intervention Group 1- Moment 1 TMI and Moment 2 CardioBreath App Group 2- Moment 1 CardioBreath App and Moment 2 TMI. The interventions will face-to-face assistance once a week for intensity adjustments, with 5 sets of 10 repetitions twice a day during week days for five weeks both for CardioBreath and IMT. Patients will be evaluated immediately after hospital discharge and at the end of the Moment 1, they will carry out a washout period of one week between the moments 1 and 2 and new evaluations before and after moment 2. The data obtained will be analyzed by intention to treat (ITT) and presented as means (M) ± standard deviation (SD). Will be tested for normality through the test by Shapiro Wilk. Differences between interventions will be detected through Student's t-test for paired samples. Correlations between variables will be obtained by Pearson's correlations for parametric and Spearman for non-parametric data, with significance level p< 0.05. Expected Results: Although there is no data comparing IMT and slow breathing in CHF patients, significant results are expected in the two intervention groups, and differences between both protocols will point to their specific applicability.

Inclusion Criteria:

• Consecutive CHF patients in treatment at the outpatient clinic (Institute of Cardiology)
• Of both sexes
• Aged between 40 and 70 years
• And ejection fraction (EF) reduced (<40%)
• Who have access to a mobile device with access to Internet.

Exclusion Criteria:

• active smoking
• BMI <30
• Diagnosis of sleep apnea
• Heart failure of congenital origin
• Valve disease.

Double (Participant, Outcomes Assessor) Participants will not know about other arms. Outcome assessors will not know the arms participant belong.