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Abstract Myocardial infarction (MI) is the irreversible necrosis of heart muscle secondary to prolonged severe ischemia. Approximately 1.5 million cases of myocardial infarction occur annually in the United States. Infarctions can be classified into ST elevation (STEMI) and non- ST elevation (NSTEMI) myocardial infarctions. STEMI can be subdivided into anterior, lateral, inferior, posterior and right infarctions based on ECG pattern of ST elevation. Assessment of Left ventricular (LV) function has become standard practice after MI while assessment of the right ventricular (RV) function remains uncommon. Recent studies suggest that RV function is an independent predictor of mortality and development of heart failure (HF) in patients with known LV dysfunction due to MI. In common practice, clinicians largely rely on non‐invasive imaging methods for assessment of RV function, thus two dimensional (2-D) echocardiography is the mainstay for analysis of RV function. Recently alternative techniques have been proposed, including tissue Doppler imaging (TDI) techniques, three dimensional (3D) echocardiography, magnetic resonance imaging (MRI) and speckle tracking echocardiography (STE). However, two-dimensional (2D) speckle tracking echocardiography (STE) provides more accurate estimates of RV function when compared to cardiac MRI reference, a finding that encouraged us to use this technique in our study. Speckle tracking allows the assessment of myocardial strain and strain rate. Myocardial strain is a dimensionless index of tissue deformation expressed as a fraction or percent change. Myocardial lengthening gives a positive and shortening gives a negative strain value. Strain rate (SR) measures the local rate of deformation per unit time. Strain can be further subdivided into longitudinal, radial and circumferential strain. Longitudinal strain represents myocardial deformation directed from the base to the apex. Radial strain represents radially directed myocardial deformation, i.e. toward the center of the LV cavity, and thus indicates the LV thickening and thinning motion during the cardiac cycle. Circumferential strain represents LV myocardial fiber shortening along the circular perimeter observed on a short-axis view. Two-dimensional (2D) strain and strain rate (SR) analyses are novel Doppler-independent techniques to obtain measurements of myocardial movement and deformation. Aim of the work: According to the previous data, we designed this work to study the right ventricular function using 2-D echocardiographic speckle tracking to measure longitudinal strain and strain rate in patients experiencing anterior myocardial infarction. Furthermore, the right ventricle was also assessed by measuring its 2-D internal dimensions, calculating fractional area change (FAC), measuring tricuspid annular plane systolic excursion (TAPSE), estimating myocardial performance index (MPI) and identifying the tissue doppler peak S wave on RV free wall at the level of tricuspid valve annulus. It was important to assess the left ventricle by conventional and 2-D speckle tracking echocardiographic techniques also in order to study the RV function in view of LV dysfunction. Subjects and methods: This study was carried out on 45 subjects in the Cardiology Department, Faculty of Medicine, Menoufia University in the period between the 1/1/ 2014 and 31/8/2014. Subjects were divided into group I (25 patients) and group II (20 controls). Patients were diagnosed as having anterior STEMI for the first time within 1 week of presentation treated with thrombolytic therapy in the first 24 hours. All subjects were subjected to full history taking, thorough clinical examination and echocardiographic assessment using GE Healthcare Vingmed Horten Norway vivid S5 echo-machine and its 3S transducer. Images were analyzed offline using EchoPac version 110.1.2 software. Conventional echocardiographic measurements of the left ventricle included (LVEDD, LVESD, LVIVSd, LVPWd, EF M-Mode and EF Simpson’s technique). Right side measurements included right atrial and right ventricular internal dimensions, TAPSE, FAC and tissue doppler peak S wave for RV free wall at tricuspid valve annular level. Twodimensional speckle tracking was done to evaluate peak longitudinal systolic strain (PLSS) and strain rate at peak systole (SRs s-1), early diastole (SRe s-1) and late diastole (SRa s-1) for all myocardial segments (basal, mid and apical) of the left and right ventricles. Average RV free wall PLSS was calculated as the average of PLSS of its 3 segments. Global RV PLSS was calculated as the average of PLSS of the 3 segments of RV free wall and septum. Global LV PLSS was calculated as the average of PLSS of its six walls (septum, lateral, anterior, inferior, posterior and anteroseptal walls). Coronary angiography was essential to evaluate the coronary arteries and exclude patients having a significant lesion in the right coronary system causing › 50% luminal diameter stenosis. This was done to exclude RV dysfunction secondary to impaired coronary blood supply. All the obtained data were tabulated and then statistically analyzed. Results: The demographic data of the patients in this study revealed that patient’s age ranged between 33-74 years with a mean ± SD of 56.160 ± 10.688. There were 5 patients (20 %) between 30-50 years, 17 (68%) patients between 50-70 years and 3 (12%) patients more than 70 years. Patient’s height ranged between 162-184 cm with a mean ± SD of 176.640 ± 6.550. The weight of patients ranged between 70-95 kg (mean ± SD of 84.320 ± 6.945) and their body mass index ranged between 22- 29.3 (mean ± SD of 27.004 ± 1.757). The majority of patients (76%) with myocardial infarction in our study were males and only 24% were females. In our study, the incidence of myocardial infarction is significantly higher in patients with DM, Htn, dyslipidemia, and smoking (p‹0.05), whereas positive family history of IHD does not show a statistically significant impact on occurrence of MI (p›0.05). The heart rate of patients (range between 65-110 beats/minute with a mean ± SD of 84.56 ± 11.889) was higher than that of the control group (range between 61-92 beats/minute with a mean ± SD of 75.35 ± 8.431). This difference reaches a statistically significant level (p‹0.05). Ejection fraction by M mode, ejection fraction by Simpsons techniques and fractional shortening, revealed a high statistically significant difference between the two groups with group I (patients) showing a significant reduction in values (p‹0.005). Similarly, there was a significant reduction in interventricular septum diastolic dimension in group I (p‹ 0.05). No statistical difference between the two groups was found regarding left ventricular end diastolic internal dimension, left ventricular basal posterior wall diastolic thickness or left atrial and aortic root dimensions (p›0.05) On evaluation of the right side of the heart, no significant difference was detected in right atrial and the right ventricular basal and mid cavity internal dimensions. Regarding tricuspid annular plane systolic excurtion (TAPSE), there was a significant statistical significance between the two groups (p<0.001) with group I showing marked reduction of values (Mean ± SD 1.940 ± 0.269 in group I vs 2.355 ± 0.343 in group II) (Table 2). There was also a significant reduction in fractional area change (FAC) in the apical 4 chamber view, our results showed that the patient group was more affected and FAC values were reduced in comparison to the control group (Mean ± SD 49.600 ± 9.363 for group I vs Mean ± SD 55.650 ± 8.177 for group II) (p<0.05). Furthermore a highly significant reduction in lateral tricuspid annulus DTI peak S wave (p‹0.005) was discovered in group I (Mean ± SD 12.560 ± 1.685 in group I vs 15.500 ± 2.373 in group II) (p<0.001). On calculating the RV MPI there was a significant difference between the two groups being markedly elevated in the patient group with (Mean ± SD 0.5637 ± 0.089) in comparison to control group with (Mean ± SD 0.3613 ± 0.067) (p<0.05). Regarding peak longitudinal systolic strain (PLSS or Esys %), the right ventricular free wall segments (basal, mid and apical) showed no significant difference between the two groups (p›0.05). Basal septal, basal posterior and basal inferior wall segments also showed no significant difference between the two groups (p›0.05). The remaining segments of the left ventricle showed a highly significant statistical reduction in group I when compared to group II (p‹0.005). As far as the strain rate at peak systole (SRs s-1) is concerned; the right ventricular free wall segments (basal, mid and apical) showed no significant difference between the two groups (p›0.05). The basal lateral, basal anterior, basal posterior and basal inferior segments also showed no significant difference between the two groups (p›0.05). The mid posterior, mid inferior and basal septal segments show a significant difference between the two groups being reduced in group I (p‹0.05). The remaining myocardial segments showed a highly significant statistical reduction in group I when compared to group II (p‹0.005). Regarding early diastolic strain rate (SRe s-1); the right ventricular free wall segments (basal, mid and apical) showed no significant difference between the two groups (p›0.05). Whereas, a significant difference was detected in the mid and basal septal and basal posterior segments between the two groups being lower in group I (p‹0.05). The remaining myocardial segments showed a highly significant difference between the two groups being significantly reduced in group I (p‹0.005). Regarding late diastolic strain rate (SRa s-1), the right ventricular free wall segments (basal, mid and apical) showed no significant difference between the two groups (p›0.05). The apical septal, apical lateral and apical anteroseptal segements showed a highly significant difference between the two groups being lower in group I (p‹0.005). The mid lateral, apical posterior, mid and basal anteroseptal segments showed a highly significant statistical difference between the two groups being significantly reduced in group I (p‹0.005). Global LV PLSS was significantly reduced in group I with a mean ± SD -9.584 ± 6.575 when compared to group II with a mean ± SD - 19.915 ± -2.073 (p‹0.005). The average RV free wall PLSS showed a slight reduction in values but not reaching a statistically significant value with a mean ± SD -25.027 ± 5.583 for group I and -26.550 ± 2.625 for group II respectively (p›0.05). SRs s-1 with a mean ± SD -2.076 ± 0.603 for group I vs -1.856 ± 0.273 for group II indicates no statistically significant difference. Septal wall average PLSS and SRs s-1 were significantly reduced in group I (mean ± SD -10.627 ± 6.106 and -0.766 ± 0.268 respectively) when compared to group II (mean ± SD -19.683 ± 2.569 and -1.228 ± 0.317 respectively) (p‹0.005). Global RV PLSS was significantly reduced in group I (mean ± SD -18.276 ± 3.956) vs group II (mean ± SD -23.120 ± 1.959) (p‹0.005). There was a significant positive correlation (r = 0.578) between Global RV PLSS and Global LV PLSS (p‹0.005). Conclusions: The Global RV PLSS is significantly reduced in patient with anterior STEMI mainly due to reduction of average septal PLSS caused by the infarction. Other parameters of the RV as TAPSE, FAC, MPI and DTI peak S wave are also affected. Furthermore, LAD territory infarction affects the PLSS, SRs s-1 and SRe s-1 of a wide area of the LV. The global LV PLSS along with EF (by M-mode and Simpsons biplane technique) appear to be significantly affected in these patients. |