Abstract
BackgroundWe investigated longitudinal right ventricular (RV) function assessed using speckle-tracking strain echocardiography in patient with myocardial infarction (MI), and identified the contributing factors for RV dysfunction.MethodsWe retrospectively studied 71 patients with old MI (the OMI group) and 45 normal subjects (the Control group) who underwent a transthoracic echocardiography. Global and free wall RV peak systolic strains (PSSs) in the longitudinal direction were measured by using speckle-tracking strain echocardiography. Left ventricular (LV) PSSs were measured in the longitudinal, radial and circumferential directions. Cardiac hemodynamics including peak systolic pulmonary artery pressure was also assessed non-invasively. Plasma brain natriuretic peptide (BNP) levels were measured in all patients.ResultsIn the OMI group, 73% of the patients had a normal estimated peak systolic pulmonary artery pressure of less than 35 mmHg. Global and free wall RV PSS were impaired in the OMI group compared with the Control group, and these RV systolic indices were significantly associated with heart rate, logarithmic transformed plasma BNP, greater than 1 year after onset of MI, Doppler-derived estimated pulmonary vascular resistance, LV systolic indices, LV mass index, infarcted segments within a territory of the left circumflex artery and residual total occlusion in the culprit right coronary artery. Multivariable linear regression analysis indicated that reduced longitudinal LV PSS in the 4-chamber view and BNP levels ≥500 pg/ml were independently associated with reduced global and free wall RV PSS. Moreover, when patients were divided into 3 groups according to plasma BNP levels (BNP <100 pg/ml; n = 31, 100 ≤BNP <500 pg/ml; n = 24, and BNP ≥500 pg/ml; n = 16), only patients with BNP ≥500 pg/ml had a strong correlation between RV PSS and longitudinal LV PSS in the 4-chamber view (r = 0.78 for global RV PSS and r = 0.71 for free wall RV PSS, p <0.05).ConclusionLongitudinal RV systolic strain depends significantly on longitudinal LV systolic strain especially in patients with high plasma BNP levels, but not on estimated peak systolic pulmonary artery pressure. These results indicate that process of RV myocardial dysfunction following MI may be governed by neurohormonal activation which causing ventricular remodeling rather than increased RV afterload.
Highlights
Myocardial infarction (MI) is associated with compensatory mechanisms involving both the left and right ventricles, and, even if the right ventricle is initially spared, right ventricular (RV) structure and function can still be altered later on [1]
The mechanisms leading to RV dysfunction following myocardial infarction (MI) in the Left ventricular (LV) myocardium are not completely clear [19], but it is frequently assumed that LV failure causes pulmonary hypertension and increased RV afterload leading to RV remodeling and dysfunction
Toldo et al assessed changes in LV and RV dimensions and function and their association with the presence and degree of pulmonary hypertension 1 week following experimental acute MI involving the LV free wall in 10 mice [20]. They found that RV fractional area change (FAC) and Tricuspid annular plane systolic excursion (TAPSE) declined by 33% and 28% respectively; invasively measured RV systolic pressure was within the normal values and unchanged following acute MI
Summary
Myocardial infarction (MI) is associated with compensatory mechanisms involving both the left and right ventricles, and, even if the right ventricle is initially spared, right ventricular (RV) structure and function can still be altered later on [1]. Since myocardial function and structure are chronically modulated by a complex interplay of multiple factors, such as hemodynamic load and neurohumoral stimulation, the mechanisms leading to RV dysfunction following MI are not completely investigated in the clinical setting [3,4]. We investigated longitudinal RV function assessed using speckletracking strain echocardiography in patient with old MI (OMI), and identified the contributing factors for RV dysfunction. We investigated longitudinal right ventricular (RV) function assessed using speckle-tracking strain echocardiography in patient with myocardial infarction (MI), and identified the contributing factors for RV dysfunction
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