Pattern of left main stenosis at a tertiary cardiac center of Nepal

Background and Aims: Left main stem stenosis is defined as a lesion occupying more than 50% of the lumen diameter. Various studies have shown that left main stem stenosis occurs in 4%-6% of all the patients undergoing coronary angiography. We aim to find out the pattern of Left main stem disease in cardiology department of a tertiary cardiac center of Nepal. Methods: : This was a retrospective study and was conducted from the properly maintained record of 2 years (August 2011 to July 2013) from cardiaccatheterization labs of Shahid Gangalal National Heart Centre, Bansbari, Kathmandu, Nepal. Results: During the study period 3290 coronary angiogram were done. Among them 102 (3.1%) patients had left main stem stenosis of more than 50%. Mean age of the patients with left main stem stenosis was 60.6±10.1yrs. Most of (73.5%) of patients with left main stem stenosis were of age more than 55 years. Most (80.3%) of them were male. Ostial left main stem stenosis was present in 32 (31.3%) patients whereas distal left main stem stenosis was present in 70 (68.6%) patients. In patients with Left main stem stenosis, single vessel disease was present in 12 (11.7%), double vessel disease in 33(32.3%) and triple vessel disease in 49 (48.0%) patients, whereas 8 (7.8%) patients with non-critical coronary artery disease. Conclusion: Left main stem disease is not an uncommon angiographic finding and is often associated with multivessel coronary artery disease. It commonly occurs in distal part of vessel and the patients were older males.


INTRODUCTION
Left main coronary artery is the most important coronary artery since it is responsible for blood supply to more than two thirds of the heart muscle.A significant left main stem (LMS) stenosis is considered to be a lesion occupying over 50% of the vessel diameter.LMS stenosis currently occurs in 4% to 6% of all patients undergoing coronary angiography (CAG) 1 and in 30% of coronary artery bypass grafting (CABG) 2 patients.
LMS stenosis occurs as an isolated lesion in 6% to 9% of patients, whereas over 70% to 80% ofpatients also have multi vessel coronary artery disease (CAD) [3][4][5][6][7][8][9][10] .As, LMS stenosis has high risk of restenosis. 11So, traditionally, CABG is the treatment of LMS coronary artery stenosis.However, drawbacks include multiple vascular anastomoses (which consume bypass conduits and can lead to complications), permanent occlusion of the LMS coronary artery, 1 and less physiologic retrograde myocardial perfusion. 12ooking at the severity of the disease and difficulties in treatment, in this study, we aim to study pattern of LMS stenosis in cardiology department of a tertiary cardiac center in Nepal.

METHOD
This was a retro prospective study single center.This study was conducted from the properly maintained record of 2 years (August 2011to July 2013) of cardiac catheterization labs of tertiary cardiac center, Shahid Gangalal National Heart Center.Records from all the patients undergoing CAGs were collected.Most trials of treatment and treatment guidelines define significant LMS stenosis as a greater than 50% diameter stenosis as judged by contrast angiography. 13Same diagnostic criteria were used in our study.Study was approved by the institution review committee of the national heart centre.All data was analyzed using SPSS 16.0.
Among the 102 patients with LMS stenosis mean age of patients was 60.6±10.1 years.Seventy Five (73.5%) patients were of age more than 55 years.Most 82 (80.3%) of them were male.Fifty three (51.9%)were hypertensive, 47 (46.0%) were diabetic.Chronic stable angina was the main reason for coronary angiogram in LMS stenosis patients as shown in

DISCUSSION
][5][6][7][8][9][10] In our study location of the lesion was distal in 70 (68.6%)patients.In a study by Saeed Sadeghian et al showed that the proportion of the male sex in those with LMS was higher than that of the ones without LMS stenosis (87.8% vs. 71.4%,P=0.020) and that patients with LMS stenosis were older (mean age of 58.8±10.5 years in those with LMS stenosis vs. 55.6±9.2 in the ones without LMS, P=0.03). 14In our study the mean age of presentation was 60.6+/-10.1yrsand the proportion of male sex was 80.3%.
So, our results were similar to international studies regarding involvement of LMS with multivessel CAD and predominance of distal vessel involvement.Several studies comparing conventional angiography with adjunctive imaging modalities have shown LMCA lesions considered angiographically indeterminate to, in fact, be severely stenosed. 16o, there may be several important limitations, which lead to a small but significant number of false-positive and false negative results, as well as significant inter-observervariability. 17

CONCLUSION
Left main stem disease is a relatively common angiographic finding and is associated with multivessel CAD.Most of the patients are older males.It commonly occurs in distal part of vessel.
Future studies are needed to show the effectiveness of other modalities like Intravascular ultrasound in diagnosis of LMS disease.

Table 1 .
Baseline characteristics of LMS stenosis patients

Table 2 .
Statistical analysis was done in various subgroups: *P value was calculated using Fischer's exact test (F test)