ABC | Volume 113, Nº2, August 2019

Original Article Maia et al Global Longitudinal Strain in Functional Capacity Arq Bras Cardiol. 2019; 113(2):188-194 Figure 1 – Global longitudinal strain index (GLS) scatter plots compared to maxVO 2 , VE/VCO 2 slope, HRR, and T 1/2 VO 2 . maxVO 2 : maximal oxygen consumption; VE/VCO 2 slope: slope of the VE/VCO 2 curve; HRR: heart rate recovery; T 1/2 VO 2 : time to VO 2 halving recovery. 60.00 40.00 20.00 0.00 300 280 260 240 220 200 180 160 140 120 100 80 60 40 20 0 –20 60.00 80.00 40.00 20.00 0.00 0.0 5.0 10.0 15.0 20.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 0.0 5.0 10.0 15.0 20.0 Strain Strain Strain Strain max VO 2 VE/VCO 2 slope HRR T 1/2 VO 2 R = 0.671; p < 0.001 R = 0.696; p < 0.001 R = 0.466; p < 0.016 R = 0.513; p < 0.007 Table 2 – Correlation of numerical variables of Cardiopulmonary Exercise Test with left ventricular ejection fraction (LVEF) and global longitudinal strain index (GLS) Variables LVEF (p value) GLS (p value) HRR-bpm 0.288 (0.154) (1) 0.466 (0.016)* (1) maxVO 2 0.585 (0.002)* (2) 0.671 (< 0.001)* (2) VE/VCO 2 slope –0.330 (0.100) (1) –0.513 (0.007)* (1) T 1/2 VO 2 –0.530 (0.005)* (1) –0.696 (< 0.001)* (1) HRR: heart rate recovery; T 1/2 VO 2 : time to VO 2 halving recovery; VE/VCO 2 slope: slope of the VE/VCO 2 curve; maxVO 2 : maximal oxygen consumption. *p < 0,05; (1) – Pearson coefficient; (2) – Spearman coefficient. Cameli et al., 13 evaluated patients with severe HF, with cardiac transplant indication, and, by histopathology of the heart after heart transplantation, found that no echocardiographic parameter, performed before heart transplant, was able to correlate with the presence of fibrosis except the GLS value. Therefore, a lower GLS value indicates that there is presence of more cardiac fibrosis, and consequently, there is less deformation and myocardium thickening, and relaxation and contractility is more defective. These changes entail low functional capacity and are responsible for worse prognosis. 13 However, in that study, functional capacity was not assessed through an objective test, such as CPET. Rangel et al. 12 evaluated patients with LVEF less than 45% and demonstrated that the GLS value correlates with more advanced stages of the disease and is an independent predictor of life expectancy. 12 That is, in patients with severe HF and similar LVEF, GLS was able to show which patients would present an unfavourable outcome. Our study showed that in patients with reduced LVEF, the lowest GLS value was correlated with CPET parameters that assess exercise tolerance and prognosis disease. When rating the GLS cut-off in predicting poor prognosis, Rangel et al. 12 used the Seattle HF model to assess the long‑term survival, and it was shown that the best GLS cut‑off point 191