Purpose: The aim of this study was to determine the relationship between ECG patterns and HCM structural phenotype assessed using echocardiography, as well as to determine the frequency of these parameters.
Methods: We collected data prospectively from consecutive patients with HCM evaluated in our center between October 2015-April 2017. The ECG tracings were analyzed for: cardiac rhythm, P wave anomalies, PR interval, QRS axis and duration, presence and extent of abnormal Q waves, hypertrophy scores, ST-T abnormalities, QTc interval. Conventional echocardiography data included left ventricular (LV) septal and posterior wall thickness, LV maximal wall thickness (MWT), presence of dynamic obstruction, left atrial (LA) and right atrial (RA) anomalies.
Results: The study included 154 patients (57.1% men), mean age 55±14 years. Left atrial enlargement as defined by ECG criteria (64% when considering V1 changes and only 13% of cases when criteria included also changes in unipolar leads) did not correlate with LA dilatation detected by echocardiography (80% patients). In our population, we observed that the mean left atrial volume is greater in patients with atrial fibrillation and furthermore we analized these data in correlation with the type of atrial fibrillation and showed that the left atrial tends to enlarge as AF becomes permanent (from 107±32 ml for paroxystic AF, to 146±72 ml for permanent AF). The interventricular septum was predominantly affected (mean value of 19.5 ± 5mm) when compared with the posterior wall thus reflecting the asymmetrical distribution of hypertrophy. However, no correlation was found between LV maximum wall thickness and the Sokolow Lyon, Cornell or Romhilt-Estes scores. The sensitivity and specificity of Cornell index are higher compared with Romhilt-Estes score, which appears to have, however, a greater positive predictive value. The prevalence of complete AV block seems to be low (3%) and not characteristic for patients with sarcomeric HCM. The giant inverted T waves (>10 mm) were found to predict the presence of apical HCM (p<0.001).
Conclusions: This study demonstrates that normal electrocardiograms are unusual in all subgroups of patients with hypertrophic cardiomyopathy. Not all ECG indices used in clinical practice have similar sensitivity, however using a multiparametric approach usually describes well the severity of structural anomalies.