Linear regression is a statistical procedure for calculating the value of a dependent variable from an independent variable. Linear regression measures the association between two variables. It is a modeling technique where a dependent variable is predicted based on one or more independent variables. Linear regression analysis is the most widely used of all statistical techniques. This article explains the basic concepts and explains how we can do linear regression calculations in SPSS and excel.

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In medical research, there are studies which often collect data on categorical variables that can be summarized as a series of counts. These counts are commonly arranged in a tabular format known as a contingency table. The chi-square test statistic can be used to evaluate whether there is an association between the rows and columns in a contingency table. More specifically, this statistic can be used to determine whether there is any difference between the study groups in the proportions of the risk factor of interest. Chi-square test and the logic of hypothesis testing were developed by Karl Pearson. This article describes in detail what is a chi-square test, on which type of data it is used, the assumptions associated with its application, how to manually calculate it and how to make use of an online calculator for calculating the Chi-square statistics and its associated P-value.

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The Bland–Altman plot is a method for comparing two measurements of the same variable. The concept is that X-axis is the mean of your two measurements, and the Y-axis is the difference between the two measurements. The chart can then highlight anomalies, for example, if one method always gives too high a result, then all points are above or below the zero line. It can also reveal that one method overestimates high values and underestimates low values. If the points on the Bland–Altman plot are scattered all over the place, above and below zero, then it suggests that there is no consistent bias of one approach versus the other. It is, therefore, a good first step for two measurement techniques of a variable.

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Introduction: There are few data on heart failure (HF) burden and none available on the community prevalence of HF in India. We conducted a study aimed at determining the HF prevalence in a rural community as well as tertiary hospital care setting in North India. We also reviewed the existing literature regarding the estimated and projected prevalence of HF in India. Methodology: All adults (>20 years) with chronic breathlessness in six villages under a primary health care center in Northern India were identified and evaluated with standardized questionnaire and physical examination by trained health care workers. HF was diagnosed by standardized criteria and a transthoracic echocardiogram was performed in all subjects. In the hospital study, 500 consecutive patients presenting to our tertiary referral hospital were evaluated for the diagnosis of HF. For the systematic review, all published studies addressing HF or the burden of risk factors in India were identified. Projections for the absolute HF burden were made using local data and global studies of HF incidence, morbidity, and mortality. Results: Among the surveyed rural adult population of 10,163 patients, chronic breathlessness was present in 128 (1.3%). HF was present in 9% (n = 12), of which 67% (n = 8) had preserved left ventricular (LV) systolic function and 33% (n = 4) had LV systolic dysfunction. Therefore, the prevalence of HF in this general community was 1.2/1000. All patients with HF and preserved ejection fraction had poorly controlled hypertension. In the hospital study, of 500 consecutive patients, 20.4% had HF. Rheumatic heart disease (52%) was the most common cause followed by ischemic heart disease (17%). The mean age of presentation was 39 ± 16 years. The prevalence of HF in the outpatient department patients was 22.5% below 30 years and 14.9% above 50 years, reflecting the young population of HF. For the estimates concerning HF burden in India, projections were made using both age-specific extrapolations from developing countries and data regarding development of HF in the presence of risk factors. The estimated prevalence of HF is about 1% of the total population or about 8–10 million individuals. The estimated mortality attributable to HF is about 0.1–0.16 million individuals per year. Conclusions: While our hospital data are consistent with the HF burden and etiology expected in a government tertiary hospital setting, our community-based study is the first of its kind reported from India. The community study demonstrates a surprisingly low prevalence of symptomatic HF in the surveyed villages. This could be partially explained by the rural farming-based community setting but is also likely due to under-reporting of symptoms. Our review of the projected national estimates suggests an alarming burden of HF in India despite a younger population than the developed nations. A significant proportion of this burden may be preventable with better screening and early and adequate treatment of the risk factors.

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Sampling is one of the most important factors which determines the accuracy of a study. This article review the sampling techniques used in research including Probability sampling techniques, which include simple random sampling, systematic random sampling and stratified random sampling and Non-probability sampling, which include quota sampling, self-selection sampling, convenience sampling, snowball sampling and purposive sampling.

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Correlation is a statistical procedure to test the relationship between quantitative variables and categorical variables. In other words, it describes the degree of relation between two variables. It is one of the most commonly used statistical techniques. The present article is based on selected statistical textbook, review of the literature, and our own research experience study.

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Background: Acute coronary syndrome (ACS) is a potentially life-threatening condition which is more common in elderly people, and young are relatively protected. Currently, the protective effect on young from coronary artery disease (CAD) is taken away by several risk factors. The aim of this study is to determine the conventional risk factors and angiographic correlation of CAD in young age (<40 years) to that of elderly age (>40 years). Materials and Methods: This study was a hospital-based retrospective cross-sectional analytical study involving 1151 patients of ACS admitted in the cardiac ICU from May 2016 to May 2018. Among these patients, coronary risk factors such as smoking, diabetes, hypertension, dyslipidemia, and family history were studied. Patients were divided into two groups, Group A: <40 years and Group B: >40 years. Patients were evaluated angiographically. The significance of each risk factor between the groups was calculated by employing the Chi-square test and P < 0.05 was taken as statistically significant. Results: A total of 1151 cases were included in the study, of which 120 cases were <40 years of age. The prevalence of CAD in young in our study is 10.42% with male preponderance. P value is statistically significant (P < 0.05) among younger individuals for smoking, dyslipidemia, obesity, family history. Of 120 cases with critical CAD, single-vessel disease (SVD), predominantly the left anterior descending artery, was the most prevalent. SVD and recanalized coronaries were statistically significant among younger group whereas triple-vessel disease (TVD) is statistically significant among the elderly. Thrombus burden is more in young when compared to the elderly. Conclusion: Although ACS is a less common entity in young adults aged 40 years or less, recent epidemiological trend is progressing and it constitutes an important challenge both for a patient and for a treating physician. Young patients with CAD are mainly males, and SVD is more common. Emphasis should be given on diagnosis and management of risk factors in this vulnerable group to prevent mortality and morbidity.

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Organ donation is one of the greatest medical marvels of the twentieth century which has saved the lives of several patients. The disparity between the huge demands for the organs and their poor supply is the main issue. The total organ donation shortage in our country can be met even if only few victims involved in fatal accidents serve as organ donors. Organ donation and successful retrieval of life saving organs is a complex process involving co-ordination of multiple transplant teams. This article reviews the different kinds of organ donors, evolution and present status of organ donation program in India, legal aspects of organ donation, process of pledging organs by a living person and the efforts taken to promote awareness about organ donation.

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Student's t-test is a method of testing hypotheses about the mean of a small sample drawn from a normally distributed population when the population standard deviation is unknown. In 1908 William Sealy Gosset, an Englishman publishing under the pseudonym Student, developed the t-test. This article discusses the types of T test and shows a simple way of doing a T test.

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Regression analysis is using the relationship between a known value and an unknown variable to estimate the unknown one. Here, an estimate of the dependent variable is made corresponding to given values of independent variables by placing the relationship between the variables in the form of a regression line. To determine how well the regression line obtained fits the given data points, F-test of overall significance is conducted. The issues involved in the F-test of overall significance are many and mathematics involved is rigorous, especially when more than two variables are involved. This study describes in details how the test can be conducted and finally gives the simplified approach of test using an online calculator.

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Background: The selection of the correct donor lung is crucial for a successful lung transplant. Since the median survival after lung transplant is 5 years and the morbidity and mortality of lung transplant is higher than other transplants, it is crucial to preselect the correct recipient. Methodology: In India, Dr. P. Venugopal at the All India Institute of Medical Sciences, New Delhi, performed the first successful heart transplant, while Dr. K. M. Cherian performed the first heart–lung transplant at Chennai. At Apollo Hopsitals, Chennai, the first heart transplant was performed by Dr. M. R. Girinath. Subsequently, the Department of Heart and Lung Transplantation at Apollo Hospitals, Chennai, have performed a large number of heart and lung transplants and its experience is summarized. Results: The Department of Heart and Lung Transplantation at Apollo Hospitals, Chennai, has done 101 lung and 62 heart transplants as part of their lung and heart lung transplant program. There were 21 heart–lung transplants and 25 double lung transplants. The results are discussed and indications, contraindications for lung and heart–lung transplant as well as recipient and donor workup are discussed in this first part of a set of three articles. Conclusions: Careful selection of a recipient and donor leads to a successful lung and heart–lung transplant program.

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Objectives: There is a paucity of data on acute decompensated heart failure (ADHF) in Indian patients. We herein report the in-hospital and 6-month outcome of Indian patients admitted with ADHF. Methods: We prospectively enrolled consecutive patients with ADHF due to systolic dysfunction in the acute failure registry and followed them up for at least 6 months. We analyzed the data on death and hospitalization of the first 90 patients on death and hospitalization over 6-months. Results: A total of 90 patients were enrolled with a mean age of 53.5 ± 17. 7 years and the majority were male (63%). The mean left ventricular ejection fraction was 29.2± 11.9%. The in hospital mortality was 30.8%. Postdischarge 6-month major adverse event (re-hospitalization/mortality combined) and mortality rates were 39.5% and 26.3%, respectively. Conclusions: These data from a single referral center provide insights into the current status of acute HF care in India. We report a higher in-hospital and follow-up mortality rates in ADHF patients who present at younger ages than reported in Western literature.

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Objective: Cardiovascular disease is the leading cause of death among Indian adults, and approximately 50% of deaths usually occur during the 1^st hour after symptom onset before arriving at the hospital. A study was planned to evaluate the prehospital and hospital delay in patients with acute myocardial infarction (AMI). Methods: This was a prospective observational study of 390 patients with AMI admitted to the Department of Cardiology between March 2014 and August 2015. Detailed patient demographics, socioeconomic status, and prehospital and hospital delay were reviewed. Results: The mean age of presentation for male and female was 57 ± 12.91 and 61.5 ± 12.83 years, respectively. The mean prehospital delay, time to act after chest pain, and travel time were 9.08 ± 6.3, 7.16 ± 6.1, and 1.84 ± 0.8 h, respectively, and only three (9.7%) patients reached the hospital within 2 h after symptom onset. Out of 300 patients who received reperfusion therapy, thrombolysis was done in 276 (92%) patients while primary percutaneous coronary intervention was performed in only 24 (8%) patients. Mean door-to-needle (D-N) time and door-to-device time for those who received reperfusion therapy were 27.8 ± 4.3 and 78.95 ± 9.5 min, respectively. A multivariate logistic regression analysis revealed that the prehospital delay was significantly associated with older age, female sex, rural background, diabetes, having atypical pain, and lack of knowledge regarding the seriousness of chest pain. Conclusion: Approximately 79% of total prehospital delay was due to patient-related factors; old age, female sex, rural background, diabetes, atypical angina, and lack of knowledge being the significant attributes. D-N time and door-to-device time were within the limits of those recommended by current guidelines.

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The potential source of complexity while analyzing the data is to choose on whether the data collected could be analyzed properly by the application of parametric tests or nonparametric tests. This concern cannot be underrated as there are certain assumptions which should be fulfilled before analyzing the data by applying either of the two types of tests. This article describes in detail the difference between parametric and nonparametric tests, when to apply which and the advantages of using one over the other.

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Heart failure (HF) is a major health problem in India with a postadmission mortality of 20%–30%. Medication adherence ranges from 25% to 50%, and the tolerance of guideline-based medication is low for Indian patients. We took out guidelines on HF in 2015, and this update covers the changes which have occurred in HF management in the past 2 years. As a number of new drugs such as angiotensin receptor-neprilysin inhibitor and ivabradine have been approved for use in India, devices such as implantable cardioverter-defibrillators and cardiac resynchronization therapy are becoming more accessible and more left ventricular assist devices and transplants are being done in India, there is need for clear guidelines for the use of each which are practical for India.

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The Number Needed To Treat (NNT) is a measure used in epidemiology to convey the effectiveness of an intervention. It is the average number of patients who need to be treated to prevent one bad outcome. It is the reverse of the Absolute Risk Reduction. The lower the NNT, the more effective the intervention. In this article we discuss the concept and limitations of this measure.

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The new US blood pressure guideline lowers the definition of high blood pressure to 130/80 mm Hg.The new guideline adopts a key component of the 2013 cholesterol guideline and incorporates overall cardiovascular risk. The AAFP has decided to not endorse the recent hypertension guideline because it gave undue importance to the SPRINT trial and cardiovascular risk which was not validated and would lead to overtreatment. The guidelines are discussed in this article.

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Norman Shumway is widely regarded as the father of heart transplantation although the world's first adult human heart transplant was performed by Christiaan Barnard, on December 3, 1967, at the Groote Schuur Hospital in Cape Town, South Africa. Adrian Kantrowitz performed the world's first pediatric heart transplant on December 6, 1967 and Norman Shumway performed the first adult heart transplant in the United States on January 6, 1968, at the Stanford University Hospital. In India, PK Sen attempted the first heart transplant in humans soon after Christaan Barnaard but the first and subsequent patients died. The first successful heart transplant in India was by Dr. P Venugopal in 1994 at AIIMS, New Delhi. This was followed soon after by Dr. KM Cherian who also did the first pediatric and first heart lung transplant in India.

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The historical evolution of the prosthetic heart valves from the first attempts with the Hufnagel's valve in the treatment of the aortic insufficiency to the Starr-Edwards' ball valve and later the tilting disc valves (Bjork-Shiley etc.,) and finally the bileaflet valves (St. Jude) are discussed. The Indian contribution with Chitra valve is also described.

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Background: Hypertrophic cardiomyopathy (HCM) is a genetic disorder with the prevalence of 1 in 500 globally. HCM is clinically characterized by thickening of the wall of the heart, predominantly left ventricle (LV), and interventricular septum (IVS). Our study aims to report the demographical, clinical and genetic profile of Indian HCM patients. Methods: HCM patients were recruited on the basis of WHO criteria. The clinical phenotypes were analyzed using electrocardiography, two-dimensional electrocardiography, and hotspot region of the MYH7 gene was sequenced for all patients as well as for controls. Results: There were 59 patients with a clinical diagnosis of HCM with a preponderance of disease in males with a ratio (men, women) of 5.5:1. Average age of onset of the disease was late 30 s (39.2 ± 14.5) with familial HCM accounting for 18% (n = 9) for total HCM families (n = 50). Nonobstructive kind of HCM was more prevalent as compared to obstructive HCM (66.1% vs. 33.9%). Average posterior wall LV thickness of the HCM patients was 16 ± 4.8 mm and IVS thickness was 21 ± 8.3 mm with familial patients having greater wall thickness as compared to sporadic patients. Sequencing of hotspot region of MYH7 identified three mutations in three different patients. Two mutations were found to be segregating in familial cases. Conclusion: HCM is more prevalent in males with a predominance of hypertrophic nonobstructive cardiomyopathy form. Eighteen percent of cases were familial and showed an early onset of the disease and worse prognosis as compared to sporadic cases. Hotspot sequencing of MYH7 only explains 6% of its genetic basis. More of the candidate genes need to be screened through advanced techniques like next generation sequencing to identify the causal genes which could make us understand the mechanistic pathways.

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Background: Mesenchymal stem cells (MSCs) are multipotent and can be easily cultured and expanded. Therefore, these are considered to be an attractive therapeutic tool for cardiac repair. These have been found to have tremendous potential to transdifferentiate to cardiac lineage both in vitro and in vivo. A number of chemicals and growth factors have been explored for the same. However, the effect of the paracrine factors released by cardiac tissue has not been studied much. Materials and Methods: In the present study, we have examined the differentiation capacity of conditioned media (CM) derived from human cardiac tissue on human bone marrow-derived MSCs (BM-MSCs). BM-MSCs after characterization were induced by culture supernatant collected from human cardiac tissue (21 days). Parallel cultures treated with 5-azacytidine (AZA) (30 days), were taken as controls. Results: MSCs treated with CM formed “muscle island” like structure and were found to be positive for cardiac-specific markers - myosin light chain-2v and cardiac troponin I proteins. However, uninduced BM-MSCs did not show positivity for any of these markers and maintained fibroblastic morphology. Conclusion: These findings demonstrate that cardiac CM is capable of effective induction of morphological and molecular changes in MSCs toward cardiac features. However, differentiation efficiency is less than that of 5-AZA and the mode of action and the components of CM are still to be known.

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Atrial fibrillation (AF) is becoming a major public health burden worldwide, and its prevalence is set to increase owing to the increase in the elderly population. Despite the availability of good epidemiological data on the prevalence of AF in the Western countries, the corresponding data are limited from our country. In this article, we have tried to assimilate all the data available. A national registry on AF does provide some insight into the causes and effects. It is necessary to have a precise knowledge of the national burden for formulating national evidence-based policy and guidelines.

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The emergence of COVID-19 has impacted heart transplantation worldwide. The pandemic has impacted donor availability and also raised issues of safety of receipients and surgical teams. In these recommendations, the Indian Society of Heart and Lung Transplantation (INSHLT) has discussed the issues related to the testing and safety issues related to the donor and the recipient as well as the surgical teams. The INSHLT recommends COVID-19 testing once consent for organ donation is obtained of both the donor and the receipient. The INSHLT also recommends high-resolution computed tomography of the chest before organ donation, especially for lung donation.

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The emergence of COVID-19 has impacted heart transplantation worldwide. The pandemic has impacted donor availability and also raised issues of safety of receipients and surgical teams. In these recommendations, the Indian Society of Heart and Lung Transplantation (INSHLT) has discussed the issues related to the testing and safety issues related to the donor and the recipient as well as the surgical teams. The INSHLT recommends COVID-19 testing once consent for organ donation is obtained of both the donor and the receipient. The INSHLT also recommends high-resolution computed tomography of the chest before organ donation, especially for lung donation.

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The association between group A streptococcal infection and rheumatic fever (RF) was established in the early 20 ^th century. At the time, RF and subsequent rheumatic heart disease (RHD) were an untreatable scourge of young people in developed and developing countries. Resultingly, research efforts to understand, treat and prevent the disease were widepread. The development of antibiotics in the 1930s offered therapeutic promise, although antibotic treatment of acute RF had little impact. Improved understanding of the post-infectious nature of RF prompted attempts to use antibiotics prophylactically. Regular doses of sulphonamide antibiotics following RF appeared to reduce disease progression to RHD. Development of penicillin and later, benzathine penicillin G, was a further thereputic advance in the 1950s. No new prophylactic options against RF have emerged in the intervening 60 years, and delivery of regularly scheduled BPG injections remains a world wide challenge.

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