**2. Epidemiological transition and cardiovascular diseases in Africa**

Epidemiological transition can be defined as the transition, under the influence of socio-economic development and aging, from predominantly infectious diseases to mainly chronic non-communicable diseases [1]. This concept was first introduced in the 1971's by Omrad and Olshansky, and Ault later on refined its meaning [2]. The transition process according to Omrad was in three ages or phases [2]: The age of pestilence and famine, the age of receding pandemics, and the age of degenerative and man-made diseases.

The age of pestilence and famine is characterized by a period of high infant and child mortality with a low mean life expectancy of less than 30 years. This stemmed from the high rate of malnutrition and infectious diseases or communicable disease like tuberculosis, pneumonia, and diarrheal diseases in Africa; with less than 10% of the mortality rate due to cardiovascular diseases [2, 3]. The age of receding pandemics is characterized by an improvement in public health policies and nutrition patterns leading to a decrease in the rate of infant and child deaths from to malnutrition and infectious diseases. This decrease in mortality was accompanied by a rise in the life expectancy from 30 to 50 years or more [2, 3]. The age of degenerative and man-made diseases is marked by an excessive intake of fat and calories with a decrease in physical activity leading to the emergence of non-communicable diseases (NCDs) such as ischemic heart diseases and heart failure. An increase in life expectancy as a result of a reduction in the mortality rate of infectious or communicable diseases tremendously marked the age of degenerative and man-made diseases. On the other hand, there is a higher death rate shift in NCD, more specifically cardiovascular diseases (CVDs). The death rate due to CVDs varies between 35 and 65% of the overall mortality rate [2, 3]. The challenges entail strengthening the prevention and improvement of the management of CVD.

Low- to middle-income countries (LMICs) in Sub-Saharan Africa (SSA) are of the epidemiological transition process [4]. A 20-year assessment of the disease burden in SSA between 1990 to 2010 shows a decline in premature mortality and disability attributable to neonatal, nutritional and maternal communicable diseases, including lower respiratory infections and diarrhoeal diseases [4]. It is worth mentioning that there were communicable diseases that occur permanently with the same high mortality rate over these 20 years-periods [4]. With only 12% of the world's population in Africa, Africa bears a considerable proportion of the global burden of tuberculosis, HIV/AIDS and malaria with rates of 31%, 62% and 70% respectively [5]. Besides communicable diseases, the disease burden due to NCDs is not trivial. Between 1990 to 2010, the disease burden from several NCDs increased, particularly stroke, depression, diabetes, and ischemic heart disease [4]. An assessment made in SSA from 1990 to 2017 shows a 67% growth in the total number of disability-adjusted lives (DALYS) due to NCDs (90.6 million in 1990 and 151.3 million in 2017) [6]. The increment in NCDs in SSA was mainly flued by CVDs, ranked as the second leading cause of the NCD burden in 2017, resulting in 22.9 (21.5–24.3) million DALYs (15.1% of the total NCD burden), after the group of disorders categorized as other NCDs (28.8 million [25.1–33.0] DALYs, 19.1%) [6]. This data show the progressive and increasing installation of NCDs in Africa and their impact on morbidity and mortality.
