Utility of Real Time 3D Echocardiography for the Assessment of Left Ventricular Mass in Patients with Hypertrophic Cardiomyopathy: Comparison with Cardiac Magnetic Resonance.

INTRODUCTION AND OBJECTIVES: Patients with hypertrophic cardiomyopathy (HCM) have irregular ventricular shapes with small and sometimes obliterated cavities at end-systole that affect the quantification of left ventricular mass (LVM) by conventional methods, such as M-mode or two-dimensional echocardiography. The goal of this study was to validate the use of real time three-dimensional echocardiography (RT3DE) to quantify LVM using cardiac magnetic resonance imaging (CMR) as a reference, in a large population of patients with different types of HCM. METHODS: Forty-eight consecutive patients with HCM had a complete transthoracic examination and CMR performed within 7 days. LVM was calculated by M-mode and RT3DE and compared to CMR that served as gold standard. RESULTS: Left ventricular mass calculated by RT3DE was 195 ± 41 g and 187 ± 49 g by CMR. The correlation between the two methods was moderate, with a Lin index of 0.63 and good linear correlation (r = 0.63, P < 0.0001). The correlation was high when RT3DE was of high or adequate image quality. The correlation between LVM by M-mode and CMR was poor. CONCLUSION: Three-dimensional echocardiography is an accurate method for the quantification of LVM in patients with different subtypes of HCM that is in better agreement with CMR reference values than M-mode measurements.

Utilidad de la resonancia magnética cardíaca en la valoración de los pacientes con dolor torácico, troponinas elevadas y ausencia de obstrucción arterial coronaria / Cardiac Magnetic Resonance Imaging in Patients with Chest Pain, High Troponin Levels and Absence of Coronary Artery Obstruction

El infarto de miocardio con coronarias angiográficamente normales tiene una prevalencia de aproximadamente el 7-10%. Muchas veces, el diagnóstico etiológico es dificultoso, y tiene importancia tanto en la clínica como en el pronóstico. El objetivo de nuestro estudio fue mostrar una serie consecutiva de pacientes con diagnóstico inicial de síndrome coronario agudo con elevación de troponina y ausencia de obstrucción arterial coronaria; en los cuales, la RM cardíaca (RMC) orientó al diagnóstico etiológico mediante la caracterización de la lesión miocárdica. Desde enero de 2005 hasta diciembre de 2009 ingresaron 720 pacientes consecutivos, con diagnóstico inicial de síndrome coronario agudo y troponinas positivas, de los cuales, 64 no presentaron lesiones coronarias angiográficamente significativas. A estos pacientes, luego del cateterismo (dentro de las 72 ± 24 hs) se les practicó RMC, realizándose secuencias de cine (b-SSFP) en eje corto, con 2, 3 y 4 cámaras para valorar la motilidad segmentaria, en secuencias potenciadas en T2 e imágenes de realce tardío del miocardio (RTM) con secuencia "inversión-recuperación". De estos pacientes, 39 fueron diagnosticados de miocarditis; 12 con infartos, 8 con síndrome de Takotsubo, 2 con miocardiopatía hipertrófica apical y solo 3 casos quedaron sin diagnóstico. Estos hallazgos ponen de manifiesto la gran utilidad de la RMC en el escenario clínico de síndromes de dolor precordial, ECG no definitivos y troponinas elevadas con arterias angiográficamente normales. La presencia de RTM y su patrón de distribución permiten definir el diagnóstico etiológico y orientar a la interpretación del proceso fisiopatológico.

The prevalence of myocardial infarction with angiographically normal coronary arteries is approximately 7-10%. The etiological diagnosis is sometimes difficult and is important in terms of clinical practice and prognosis. The goal of our study was to show a series of consecutive patients with an initial diagnosis of acute coronary syndrome with high troponin levels and absence of coronary artery obstruction in which cardiac magnetic resonance imaging (CMRI) gave a description of the myocardial lesion, orientating towards the etiological diagnosis. From January 2005 to December 2009, 720 consecutive patients with an initial diagnosis of acute coronary syndrome and elevated troponins were included; 64 of these patients did not present angiographically significant coronary artery stenosis. Within 72 ± 24 h after coronary angiography, these patients underwent CMRI using b-SSFP sequences for cine imaging in short-axis, 2-, 3- and 4- chamber views for the evaluation of segmental wall motion, with T2-weighted and delayed enhancement (DE) images of the myocardium with an "inversion-recovery" sequence. The following diagnoses were made: myocarditis (39 patients); myocardial infarction (12 patients); Tako-Tsubo syndrome (8 patients); apical hypertrophic cardiomyopathy (2 patients); 3 patients remained without diagnosis. These findings demonstrate the usefulness of CMRI in the clinical scenario of patients with chest pain, inconclusive ECG findings and high troponin levels with angiographically normal coronary arteries. The presence and distribution pattern of DE make it possible to define the etiological diagnosis and interpret the physiopathological process.