ABC | Volume 110, Nº2, February 2018

Review Article Perrier-Melo et al Interval exercise in heart transplant recipients Arq Bras Cardiol. 2018; 110(2):188-194 Table 1 – Strategy of the bibliographic search in data bases and portals. #1 “ heart recipient ”[tiab], OR “ heart transplant recipient ”[tiab], OR ” heart transplant ” [tiab], OR “ cardiac transplant ” [tiab], OR “ heart graft ” [tiab], OR” heart transplantation ’’[Mesh], OR “ cardiac transplantation ” [Mesh] #2 “ exercise training ” [tiab], OR “ interval training ” [tiab], OR “ high intensity interval training ” [tiab], OR “ high intensity training ” [tiab], OR “ anaerobic training ” [tiab], OR “ intermittent training ” [tiab], OR “ sprint training ” [tiab] #1 AND #2 Mesh: Medical Subject Headings characterized by sets of short- or long-lasting exertion periods (30s – 4min) at high intensity (> 85% VO 2 max), followed by short- or long-lasting recovery periods (30s – 4 min). 21 Although some studies have shown greater progress with HIIT practice as compared to MICT, HIIT is still cautiously prescribed for individuals diagnosed with cardiovascular and metabolic diseases or those who underwent an organ transplantation. In addition, little is known about the dose‑response ratio of the improvement in cardiorespiratory, endothelial and hemodynamic parameters caused by HIIT in HTx recipients. Thus, this study was aimed at assessing by use of a systematic review with meta-analysis whether HIIT can benefit those parameters. Methods A systematic review was conducted following the recommendations and meeting the criteria determined by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guideline (PRISMA ) . Search strategy The search for articles in English was conduct in the PubMed, Web of Science, Scopus, Science Direct e Wiley databases up to December 2016. The terms and descriptors used in the searching process were selected based on the keywords available in previous studies and via DeCS andMesh , respectively (Table 1). The terms identified in the literature were: “ heart recipient ” OR “ heart transplant recipient ” OR “ heart transplant ” OR “ cardiac transplant ” OR “ heart graft ”. The descriptors of DeCS andMeshwere: “ heart transplantation ’’ OR “ cardiac transplantation ”. The words used in combination (AND) were “ exercise training ” OR “ interval training ” OR “ high intensity interval training ” OR “ high intensity training ” OR “ anaerobic training ” OR “ intermittent training ” OR “ sprint training ”. Data extraction and all processes of search, selection and assessment of articles were performed in pairs. Selection criteria The inclusion criteria were as follows: a) randomized studies assessing VO 2 peak (based on a maximum incremental test) and/or HRpeak as primary outcome; b) sample comprised exclusively of HTx recipients; c) studies assessing the HIIT effect; and d) studies with an intervention period longer than 4 weeks. The exclusion criteria were as follows: a) studies without a control group; b) studies with acute analysis; and c) case studies. Identification and selection of studies Initially the references were reviewed based on the titles and abstracts. Then, the relevant articles according to the selection criteria were fully read and assessed regarding their methodological quality by use of the Testex scale . 22 Data analysis The variables analyzed (VO 2 peak and HRpeak) were classified as continuous, and data were presented as mean and standard deviation. Data were combined to obtain the size of the general effect, 95% confidence interval (CI) and significance level, using the Review Manager (RevMan) software, version 5.3, Copenhagen: The Nordic Cochrane Centre. The HIIT group was compared with the control group (post-entrance) by use of weighted mean difference (WMD). For each result, heterogeneity (I 2 ) was calculated, adopting the fixed effects model. The significance level adopted was p < 0.05. Results Figure 1 shows the flowchart of the search and selection process of the articles included in this review. In the initial electronic search, 1064 potentially relevant studies were identified. After reading their titles, 994 articles were ruled out because they did not have a primary outcome related to the objective of the present review. Then, after reading the abstracts of the remaining studies, 14 were excluded because they did not meet the selection criteria of this study. Three articles with a mean score regarding methodological quality of 10 points, according to the Testex scale, were included in the final analysis. Major information regarding sample characteristics, methodology, qualitative analysis and results from the studies on HTx recipients are shown in chronological order in Tables 2 and 3. A total of 118 patients (90 men and 28 women) who had undergone HTx 5.3 ± 3.7 years before were included in the analysis of this systematic review, 60 in the HIIT group (49.3 ± 12.7 years) and 58 in the control group (53 ± 14.3 years), maintaining their usual activities. The HIIT sessions were conducted on cycle ergometers 23,24 and treadmills, 25 reaching an intensity of 80-100% of VO 2 peak or 85-95% of HRmax. Such training sessions were performed three to five times per week for 8 and 12 weeks. All studies included had VO 2 peak as the major outcome of the analysis. Figure 2 shows the increased effect on VO 2 peak [95%CI: 4.45 (2.15 - 6.75), p = 0.0001, N = 118] of HIIT (24.3 ± 6.5 – 28.0 ± 6.7 mL/kg.min; 15%) as compared to that of the control group (23.8 ± 6.0 – 23.2 ± 5.9 mL/kg.min; -2%). 189