Prevalence and patterns of coronary artery disease in patients undergoing cardiac surgery for rheumatic and non-rheumatic valvular heart disease in a tertiary care center of Nepal

Introduction Rheumatic heart disease (RHD) continues to be the dominant form of valvular heart disease in developing nations1. There are limited data regarding optimal strategies for diagnosis and treatment of coronary artery disease (CAD) in patients with valvular and non valvular heart disease having concomitant CAD. The strategies for diagnosis of CAD were followed from the smaller published series of patients who underwent surgical treatment for valvular heart disease (VHD). The pre-operative identification of CAD even in asymptomatic patients is quite significant because there is negative impact of untreated CAD both on perioperative and long term postoperative outcomes.2,3 American College of Cardiology/American Heart Association (ACC/AHA) guidelines for coronary angiography Abstract


Introduction
Rheumatic heart disease (RHD) continues to be the dominant form of valvular heart disease in developing nations 1 .There are limited data regarding optimal strategies for diagnosis and treatment of coronary artery disease (CAD) in patients with valvular and non valvular heart disease having concomitant CAD.The strategies for diagnosis of CAD were followed from Nepalese Heart Journal 2018; 15(2): 21-24 (CAG) has been followed to anticipate risks in patients with RHD and non-rheumatic VHD 4 .In clinical practice, we have noticed that prevalence rate of CAD with rheumatic origin is low among patients with valvulopathies.It is exceptional that although the non-rheumatic origin of the valvulopathies is often found in our population, the rheumatic origin still considerably outnumbers the first 5,6 .In the developed western part, CAD is more commonly associated with valvular heart disease 7 .
In several trials the incidence of associated CAD in acquired valvular diseases has been studied [8][9][10][11] .But there is limited data regarding the prevalence of CAD in rheumatic heart disease patients.It is suspected that intra myocardial coronary arteries may be involved in the form of an arteritis in rheumatic fever 12 .The clinical and autopsy findings in patients who died of myocardial infarction showed rheumatic heart disease to be quite rare 13 .Due to which it is acknowledged that myocardial infarction most commonly occurs in association with atherosclerotic heart disease.So the impact of CAD is not well formed with its relation to rheumatic valvular disease.In few studies, association of RHD with coronary artery disease results in poor prognosis. 8,10,14thods: Here we evaluate the prevalence of coexistent coronary artery disease and its risk factors in patients who underwent valve surgery for rheumatic and non-rheumatic valvular heart disease in last one year at Manmohan Cardio Vascular Thoracic and Transplant Centre (MCVTC).Non-rheumatic valvular heart diease includes degenerative valvular heart disease (DVHD), mitral valve prolapse (MVP), bicuspid aortic valve (BAV).The transthoracic echocardiogram (TTE) have been mainly used evaluate the origin of cardiac diseases.The trans-esophageal echocardiogram was also used when TTE was non-decisive, with two dimensional and color flow imaging.No tissue sampling was done.All patients underwent CAG with informed written consent.Angiogram report showing presence of coronary artery disease (defined as >50% luminal stenosis) and the number of lesioned coronary arteries were collected.

Inclusion Criteria:
Rheumatic and non-rheumatic valvular heart disease patients prior to valve replacement/repair surgery in which 1.
Men of >40 years old.
Patient presenting with symptoms of angina and objective evidence of ischemia.
Men of <40 years old.

2.
Pre-menopausal women without any symptoms of angina or objective evidence of ischemia.

3.
Patient who underwent CAG within last 3 months.

4.
Patient with history of CAD.

Statistical Analysis:
All statistical analysis was performed using SPSS version 20.0.Categorical data were analyzed in terms of frequency and continuous data presented as means ± SD.Dichotomous variables were compared by Chi-square test and independent samples t test used to compare means of continuous variables.The p value < 0.05 was considered significant.

Results:
A total of 97 patients with valvular heart diseases were included in the study.Majority of the patients (57 patients, 58.7%) had rheumatic etiology while the second most common origin was degenerative valvular heart disease (31 patients, 31.9%).The mean age of patients in rheumatic group was 51 ± 7.7 years and non-rheumatic group was 61± 9.9 years.In non-rheumatic group as mentioned in table 2, the prevalence of CAD was higher, 15 patients (68.1%), as compared to rheumatic group.CAD was most prevalent in DVHD patients (12 patients, 38.7%).Among, 12 patients of DVHD and CAD, nine had single vessel disease (SVD) (29%), two had double vessel disease (DVD) (6.5%) and only one patient had triple vessel disease (TVD) (3.2%).Out of three patients with MVP only one had CAD which was DVD (33.3%) while six patients in BAV only two had CAD both of whom had SVD (33%).
Among 22 patients with CAD, only seven patients (31.8 %) were with RHD and all of them had SVD.Thus the prevalence of CAD in rheumatic (57 patients) compared to non-rheumatic VHD (40 patients) of our study was 12.2% & 37.5 % respectively.

Discussion
In patients with valvular heart diseases, the higher number of patients had degenerative origin 15 .The overall prevalence of CAD has been shown to vary widely from 9% to 41% in patients undergoing valve replacement surgery 8,10,14,[16][17][18] .
Elderly patients had degenerative valve disease and multiple coronary risk factors.The most common origin of VHD is rheumatic in developing countries.And, the prevalence of coexistent CAD is very low in comparision to patients with western countries [19][20][21] .In our study the prevalence of coronary artery disease in all groups was 22.6%, which is very low as compare with western world.
In the study of Cholenahally Nanjappa Manjunath et al 22 the overall prevalence of coronary artery disease was 8.7%, and the prevalence in RHD was 4.9%, which is much lower when compared with our study.
Marchant et al 23 assessed coronary angiogram of 100 rheumatic valvular disease patients.According to them, the prevalence of coronary artery disease was 14%, which is quite similar to our study.
Shaikh et al 24 reviewed medical data of 144 RHD patients, 25% of whom had CAD, which might be related to the higher frequency of DM, HTN and dyslipidemia in these patients.Similar to our study, Jose et al 19 and Narang et al 25 showed that the prevalence rate of CAD in RHD patients undergoing cardiac surgery was 12.2% and 11% respectively.
Kruczan et al, 21 evaluated 294 patients with rheumatic and non-rheumatic VHD and stated that the patients with non rheumatic VHD had higher prevalence of CAD (33.61%) when compared to those with rheumatic VHD (4%).Xu et.al.reported the prevalence of CAD in DVHD to be 9.57% among 491 patients which is much lower than our study (38.7%).The prevalence of CAD was found to be lower in rheumatic origin as many patients in our study were from a lower economic and sociological position.
In the study of Choudhary et.al 27 among patients of RHD with CAD, 64(58.7%)patients had SVD, 30(27.5%)had DVD and 15(13.8%)had TVD while in non RHD with CAD 32 (29.4%) had SVD, 39(35.8%)had DVD and 38(34.9%)had TVD.In our study the most common pattern of CAD was SVD in both groups.In RHD group, all patients with CAD were found to have SVD while, in non-RHD group, only 11 patients (73.3%) had SVD.Among remaining four patients, three patients (16.7%) had DVD and one patient (5.6%) had TVD.

Limitation of the study:
This is a single center study with small sample size especially of non-rheumatic valvular heart disease like MVP and BAV.

Conclusion:
We conclude that the prevalence of CAD is higher in Nepalese patients with non-RHD in comparison to those with RHD.We also found SVD to be the most common pattern of CAD in both rheumatic and non-rheumatic valvular heart disease.

Table 1 :
Baseline Clinical Characteristics

Table 2 :
Prevalence and severity of CAD in relation to different etiologies (Rheumatic vs Non-rheumatic etiology group)