ABC | Volume 113, Nº4, October 2019

Original Article Gil et al. LV function in HCM by Strain technique Arq Bras Cardiol. 2019; 113(4):677-684 Discussion The finding of significant reduction in myocardial strain in the hypertensive group suggests that these patients present greater impairment of ventricular function. Early detection of left ventricular dysfunction with preserved ejection fraction was only possible using the strain technique, not used in previous studies. Prior to the advent of strain, no significant abnormalities were observed in the comparison between these groups. In a study conducted in 1989 by Karan et al., 17 78 patients diagnosed with HCM on echocardiography and cardiac catheterization were evaluated, including 39 hypertensive patients. Themost relevant finding was higher hypertrophy in hypertensive patients, suggesting that SAH may increase hypertrophy in HCM. This study was important to define the existence of hypertrophic cardiomyopathy with hypertension, which was previously described as hypertensive hypertrophic cardiomyopathy. In 1998, Dimitrow et al. 18 published a study with 123 patients with HCM, 19.5% of whom were hypertensive, in which only functional class was evaluated. The study found that the association of SAH was more frequent in the elderly, but not rare in young people, which had worse functional class. In another study not using the strain technique, echocardiographic findings were similar between groups and SAH was also more frequent in the elderly. 19 In 2014, Gonçalves et al. 20 performed GLS analysis in a group of 229 pure hypertensive patients without HCM and preserved EF, and observed a reduction in GLS in 15.3% of the patients. However, no studies were found in the literature using the strain technique to compare HCM patients with and without associated SAH. In addition to detecting early changes in ventricular function, strain impairment may be a predictor of ventricular arrhythmia. In a publication with 400 HCM patients, those with GLS >-10% were four times more likely to have events than patients with GLS ≤-16%. 21 Regional strain abnormalities in HCM may also be predictive of arrhythmia, as demonstrated by Correia et al. 22 A study with 32 patients found mean septal strain >-10% with 89% sensitivity and 74% specificity for the development of non-sustained ventricular tachycardia, regardless of age or maximum wall thickness. These regional strain abnormalities may be related to areas with higher percentage of fibrosis on magnetic resonance imaging, being a potential substrate for the development of arrhythmias. 23,24 Diastolic dysfunction was more evident in hypertensive patients in this sample. Hypertensive patients had a higher percentage of grade I or II dysfunction and a lower percentage of undetermined cases, according to the latest recommendations for diastolic function evaluation. 15 It should be noted that left atrial volume, an important parameter in the assessment of diastolic function, 15,25,26 was increased in both groups on average, with no significant difference between them. This means, in principle, that most patients had some degree of diastolic dysfunction, but it was better defined in hypertensive patients. Regarding the type of hypertrophy, in the classification proposed by Maron et al., 14 which evaluated 125 patients, the most frequent type was type III (52%), followed by types II (20%), IV (18%) and I (10%). In another study, Reant et al. 27 evaluated 271 patients using this classification, and the most frequently observed type was II (47%), followed by types III (35%), I (11%) and IV (7%). We have found a percentage similar to Maron’s classification regarding the most frequent types of hypertrophy, that is, types III and II, followed by types I and IV. In the hypertensive group, mean age was higher, which may have influenced the evaluation of diastolic function and, perhaps, the strain analysis. Some studies have shown that myocardial strain presents a small reduction with age. 28,29 Others have not observed a clear relationship between myocardial strain and age. 30,31 We observed that mean blood pressure was higher in the hypertensive group, but there is no definition in the literature as to whether increased blood pressure at the time of the test may influence strain analysis. Study limitations The strain technique requires regular heart rhythm, which limits its use in some situations, such as atrial fibrillation, which led to the exclusion of some patients. In the hypertensive group, mean age was higher and may have interfered with strain analysis and diastolic function analysis. Finally, long-term follow-up could provide further information about ventricular function behavior, since our study was cross-sectional. Conclusion Patients with HCM and SAH had lower myocardial strain, suggesting greater impairment of left ventricular function, even with preserved ejection fraction. This finding may be related to a worse prognosis, with early evolution to heart failure and/ or onset of ventricular arrhythmias. Prospective studies are needed to confirm this hypothesis. Author contributions Conception and design of the research: Gil TCP, Castier MB, Rocha RM; Acquisition of data: Gil TCP, Gondar AFP, Sales AF; Analysis and interpretation of the data and Writing of the manuscript: Gil TCP; Statistical analysis: Santos MO, Lima FCS; Obtaining financing: Rocha RM; Critical revision of the manuscript for intellectual content: Castier MB, Rocha RM. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding This study was funded by FAPESP. 682