ABC | Volume 110, Nº1, January 2018

Original Article Paixão et al Correlation of ECG with RM in hypertrophic cardiomyopathy Arq Bras Cardiol. 2018; 110(1):52-59 The analysis of the size of the R wave in lead DI showed higher mean (15.6 mm) in concentric hypertrophy, and lower mean in septal hypertrophy (10 mm), with a significant difference between the three groups (p = 0.0280). In lead V1, the R wave showed no difference in its size (p = 0.9563). As compared to septal and concentric hypertrophies, apical hypertrophy showed greater R wave amplitude in leads V5 and V6 (means of 26.9 mm and 26 mm, respectively), with statistical significance (p = 0.0391, p = 0.0148, respectively). Regarding ventricular repolarization, apical hypertrophy correlated with the highest T wave negativity in DI (-3.8 mm), V5 (-10.2 mm) and V6 (-7.9 mm), with statistical significance in the three leads (p < 0.001). (Table 3) Discussion Analysis of the patients with HCM showed a mild predominance of the female sex (55.9%), which differs from that reported in other studies. 2 The distribution of myocardial hypertrophy found in this study by use of magnetic resonance imaging showed predominance of the septal location of hypertrophy (69% of the cases), followed by the concentric (21%) and apical (10%) locations, similar to that reported in the literature. 9 Mid-ventricular and lateral involvements, not identified in this study, are rare, with reported prevalence of 1% to 2% of the cases. 10 The presence of delayed enhancement on cardiac magnetic resonance worsens the prognosis of patients with HCM. Moon JC et al., 11 in a prospective study with 53 patients with HCMundergoing magnetic resonance imaging with gadolinium, have concluded that the presence of fibrosis relates to the occurrence of ventricular arrhythmias, ventricular dilatation and sudden death. Concentric hypertrophy showed a bigger mass of fibrosis as compared to that of the other hypertrophy locations. The R wave amplitude in DI was higher in concentric hypertrophy, showing a possible electrocardiographic pattern correlated with that location. However, in leads V5 and V6, the R wave amplitude measured in millimeters showed a significant correlation with apical hypertrophy, in accordance with the findings of other studies. 12 The mean R wave amplitude in V5 and V6 in the apical region was 26 mm, which is similar to that described by Yamaguchi et al. in patients with apical hypertrophy confirmed on the echocardiogram. 12 The analysis of the R wave in V1 failed to show a good correlation with the anatomic pattern of hypertrophy. In addition, apical hypertrophy was related to higher T wave negativity in the leads DI, V5 and V6 (means of -3.8 mm, -10.2 mm, and -7.9 mm, respectively). Chen X et al., 13 assessing 118 patients with HCM, have observed that negative T waves associated with apical hypertrophy (p = 0.009), corroborating the present study. Giant T waves, described as inversion ≥ 10 mm in any anterior lead, were also associated with apical hypertrophy, being found in the patients of that study in leads V5 and V6. 14,15 The same relationship has been reported by Song et al., 15 studying 70 patients, who have evidenced a correlation of a deep negative T wave with apical hypertrophy on magnetic resonance imaging (p = 0.018). Regarding the analysis of the strain pattern on ECG (change in the ST segment and T wave), that electrocardiographic finding showed a 100% correlation with the anatomic location of apical hypertrophy of the left ventricle. In patients with concentric hypertrophy, that pattern of ventricular repolarization change was found in 71% of the cases, while in the septal pattern, only in 28% of the cases, with statistical significance. Sung-Hwan Kim et al., 16 analyzing 864 patients with HCM, have found that same correlation of the strain pattern with apical hypertrophy; however, that was assessed by use of echocardiography (p < 0.001). The specific analysis of that electrocardiographic finding and its correlation with magnetic resonance imaging findings in HCM have not been found in the literature. Electrocardiographic left ventricular overload was more frequently found in patients with the concentric pattern of hypertrophy (71%) than in the others (42%), but there was no statistical significance in those correlations. Previous studies have only assessed the presence or absence of electrocardiographic criteria of left ventricular overload, without comparing that finding with the location of hypertrophy. 6,17 Table 3 – Median and percentiles of the continuous variables according to location of myocardial hypertrophy Variables Group Apical Concentric Septal p-value K-W AxC AxS CxS R D1 (mm) Median (P25, P75) 9 (11; 13) 9 (14; 19.5) 5.75 (8.5; 13) 0.0280 0.6870 0.2717 0.0444 R V1 (mm) Median Median (P25, P75) 0 (1.5; 6) 0.88 (1.5; 4.13) 0 .88 (1.75; 3.25) 0.9563 R V5 (mm) Median (P25, P75) 20 (22; 35) 12 (21.5; 27) 9 (15; 22.25) 0.0391 0.5481 0.0440 0.3785 R V6 (mm) Median (P25, P75) 20 (25; 31) 9.75 (19; 21.75) 8.25 (13; 22) 0.0148 0.1577 0.0125 0.5619 T D1 (mm) Median (P25, P75) -4 (-3.5; -2) -5.13 (-2.75; -1.88) -2 (0; 2) < 0.0001 0.9725 0.0032 0.0010 T V5 (mm) Median (P25, P75) -12 (-8; -6) -6.63 (-4.5; -2) -2.5 (2; 3.5) < 0.0001 0.0487 0.0009 0.0040 T V6 (mm) Median (P25, P75) -9 (-7; -4) -6 (-3; -2.5) -3 (1; 2.5) < 0.0001 0.0685 0.0016 0.0072 P25: 25th Percentile; P75: 75th Percentile. P-values: K-W: Kruskal-Wallis test; multiple comparisons between the groups: AxC: Apical x Concentric; AxS: Apical x Septal; CxA: Concentric x Apical (Dunn’s multiple comparison test). 57