Echocardiographic Evaluation of Left Ventricular Systolic and Diastolic Dysfunction in Patients with Acute Myocardial Infarction

INTRODUCTION: Acute Myocardial Infarction is one of the leading causes of death among men and women worldwide. Most of the early deaths are due to Ventricular Arrhythmias. These Arrhythmias are responsible for the sudden deaths associated with Myocardial Infarction. The late mortality associated with Myocardial Infarction is typically due to left ventricular dysfunction and its complications. Residual Left Ventricular function after Myocardial Infarction is an important prognostic marker. Left Ventricular dysfunction can be systolic, diastolic or both. Echocardiography is the most widely used and readily available, non-invasive tool in the arsenal of cardiologist for evaluating the left ventricular function. Echocardiographic evaluation of Left Ventricular function is an integral part of evaluation of a patient with Acute Myocardial Infarction. Two Dimensional echocardiography is useful for the assessment of systolic function, and Doppler Echocardiography is well suited for studies of diastolic function. An acute Trans-mural Myocardial Infarction causes a loss of contractile fibres which reduces systolic function. Parallel to the effect on systolic function, a myocardial infarction also impacts diastolic function, as evidenced by the raise in left ventricular end diastolic pressure. This study is performed to estimate the prevalence of left ventricular systolic and diastolic dysfunction using various Echocardiographic indices in patients with Acute ST elevation Myocardial Infarction and to find out its significance in determining early in-hospital morbidity, especially early Congestive Heart Failure in such patients. AIMS AND OBJECTIVES: 1. To assess the prevalence of Left Ventricular Systolic and Diastolic dysfunction in patients with Acute Myocardial Infarction. 2. To study the association between Left Ventricular Systolic, Diastolic dysfunction and the variables such as Age, Sex, Smoking, Diabetes, Hypertension, Killip Class, Type of Myocardial Infarction. 3. To assess the relationship between the echocardiographic indices of systolic and diastolic function and the development of early in-hospital congestive heart failure (as defined by Killip Class ≥ II). MATERIALS AND METHODS: Individuals who were admitted for acute Myocardial Infarction in the Intensive Coronary Care Unit, Department of Cardiology, Govt. Stanley Hospital from April 2011 to September 2011 were evaluated in this study. Their Left Ventricular Systolic and Diastolic function was assessed by 2D Doppler Echocardiography within 48 hours of admission. Left Ventricular Ejection Fraction – the most well accepted expression of systolic Left Ventricular function is measured with the help of 2D echocardiography. Regional Wall Motion Abnormalities are also assessed and graded as: 1. Normal, 2. Hypokinesia, 3. Severe Hypokinesia –akinesia, 4. Dyskinesia, 5. Aneurysm. Inclusion Criteria: 1. Patients of both sex, aged between 30 and 60 with Acute Myocardial Infarction (STEMI) who are admitted in the Intensive Coronary Care Unit. 2. Patients undergoing thrombolysis using streptokinase. Exclusion Criteria: 1. Patients with Non ST elevation myocardial infarction. 2. Patients who have contraindications for thrombolysis. 3. Patients with previous history of myocardial infarction. 4. Patients with complete heart block. 5. Patients with atrial fibrillation. 6. Patients with other co-morbidities such as Chronic Kidney disease, Chronic Obstructive Pulmonary Disease. 7. Patients with prior history of heart failure symptoms. 8. Patients with valvular heart disease. 9. Patients with cardiomyopathies. Statistical Analysis: Data were represented as mean ± SD or percentage of the total, unless otherwise specified. Statistical analysis was done using SPSS ver. Comparison between continuous variables was done using Mann Whitney U test or ANOVA. ROC curves were plotted to determine the ideal cutoff for Echocardiographic variables for predicting heart failure. Univariate logistic regression was used to compare the clinical and echocardiographic variables with heart failure. The significant variables in univariate analysis were added to a complete model of multivariate logistic regression. P value of <0.05 was considered significant. OBSERVATIONS AND DATA ANALYSIS: All the 50 patients included in the study presented with isolated acute ST elevation Myocardial Infarction. All the patients had regional wall motion abnormalities in their Echocardiogram and underwent thrombolysis. The study group included 36 males and 14 females. The difference in sex wise distribution is obvious, as only patients between the age of 30 and 60 were included in the study and in this age group STEMI is more common in males. The age wise distribution chart shows that the incidence of STEMI increases as the age advances. It is also seen that the maximum number of female patients are in the 56-60 group, implying that the risk for MI increases during the post menopausal period. CONCLUSIONS: In this study population of 50 patients with first AMI and without previous heart failure symptoms, the incidence of early in-hospital congestive heart failure was 62% (n=31). • 48% of the patients with first AMI had diastolic dysfunction. • 50% of patients had systolic dysfunction (defined as ejection fraction of ≤ 40%). • 22% of patients had a Regional Wall Motion Scoring Index of ≥1.7. • Left ventricular ejection fraction was the most important predictor of early heart failure (p=0.004). • The cut off ≤ 40% of LVEF had a high predictive value (74% sensitivity 90% specificity) in detecting patients who are likely to develop heart failure symptoms. • Presence of Diastolic dysfunction also predicted early heart failure following AMI accurately (p=0.035). • Regional Wall Motion Index was inferior compared to LVEF and presence of DD in predicting heart failure (p=0.218). • Smokers were more likely to develop early in-hospital heart failure following AMI (p=0.045). • Diabetes was one of the important risk factors for the development of heart failure following AMI (p=0.036).