Study design:
A case control cross sectional analytical study was conducted in Islamic International Medical College, Rawalpindi in collaboration with Electrophysiology department of Armed Forces during the period of 17th September 2017 to 19th May 2018 after approval from ethical review committee of Riphah University Islamabad (ERC). A total of 90 PVCs patients between the ages of 26-60 were included in the study from Armed forces institute of cardiology patients by probability convenient sampling. All the patients were included in the study after obtaining the informed consent. All methods were carried out in accordance with relevant guidelines and regulations for treating and managing the premature ventricular contractions in the patients. Patients coming with complaints of palpitations (anxiety was ruled out after psychological assessment), chest pain, heart sinking, and dizziness were evaluated for the presence of arrhythmias. Patients with Premature ventricular contractions (PVCs) were selected and the patients with arrhythmias other than PVCs were excluded from the study. Predefined criteria for the classification of PVCs into mild, moderate and frequent PVCs burden was used to include the equal ratio of PVCs burden.
Patient’s selection:
All the patients were evaluated by physical examination, 12 –lead electrocardiography (ECG), 24 hours Holter monitoring and transthoracic echocardiography. Exercise tolerance test (ETT) was performed in all the patients. Further investigations such as multi-detector computed tomography, and MRI was done in some patients if indicated and the patients with structural heart disease and coronary artery disease were excluded from the study.
Exclusion criteria for the study included trauma, Physical impairment, pregnancy, Hypertension, severe coronary artery disease, and pneumonia ,renal failure and systolic heart failure (Ejection fraction<50%). Patients with PVCs caused by reversible causes such as electrolyte imbalance, infection or drugs were excluded. All the patients were evaluated and treated according to the proper protocols established in armed forces institute cardiology. In the end 160 patients in total were included in the study with 40 patients in each group of mild, moderate and frequent PVCs burden.
40 subjects as a control were selected from the population between the ages of 25 to 65 years. Control group included both males and females. All these patients were healthy with no history of diseases like hypertension, cardiovascular diseases, structural heart diseases etc. patients with normal BMI was included in the group.
Demographic data:
Demographic data regarding age (years) sex, height (cm), weight (kg), BMI was entered in a questionnaire Performa.
ECG and Holter analysis:
Patients with complaints of palpitations, chest pain, syncope or even asymptomatic patients (who were found to have PVCs on 12 lead ECG during their routine visits) were monitored for duration of 24 hours by Holter device (12 lead) to document any arrhythmia on advice of their attending cardiologist.
For Holter monitoring, 12 chest leads were applied to their chest and they were sent home along with Holter machine. After 24 hours Holter was removed and attached to the computer to transfer ECG data. After reading 24 hours recording of ECG, patients with ventricular ectopy/PVCs were selected and their PVCs burden was calculated. PVCs were diagnosed on 24 hours Holter monitoring and their burden was calculated by dividing the number of PVCs by total number of analyzed beats in 24 hours. According to their PVCs burden, they were divided into 3 groups of mild (<10%), moderate (10-20%) and high (>20%) burden and then the equal ratio of all the PVCs patients were taken.
Echocardiography:
Echocardiography was done in all the patients by a cardiologist. Systolic ejection fraction and diastolic ejection fraction were calculated and the patient with systolic ejection fraction less than 50% were not included in study.
Estimation of N Terminal pro BNP levels:
Blood for measurement of NT-proBNP concentrations was collected by venipuncture in polyethylene therephthalate glycol (PET) Vacuette clot and were centrifuged within one hour. Serum samples were stored at −80°C till all the samples were collected and NT-proBNP levels were measured later on. NT-proBNP was measured by electro chemiluminescent immunoassay using Human NT-proBNP ELISA kit.
(Synonyms: E-EL-M0918 Catalog No: E-EL-H0902 96T Manufacturer: Elabscience)
Statistical Analysis:
Statistical analysis was done by using spss version 25. As the data was normally distributed Continuous variables are summarized as the mean ± standard deviation and discrete variables are described as counts with percentages. Comparisons of NT –proBNP levels of control group with mild, moderate and frequent PVCs burden was performed using parametric tests. One way Analysis of variance (ANOVA) was applied. For categorical data, the chi-square test was used. Correlations between parameters were tested by Pearson’s correlation analysis