Predictors of obstructive coronary artery disease in women.

Sir,

We recently came across a very interesting article published in the Indian Heart Journal- “Development of a diagnosis model for coronary artery disease” by Hongzeng Xu et al.. It was a retrospective multi-centric study, in which authors have evaluated risk factor and angiographic profile of 7360 Chinese patients with suspected coronary artery disease (CAD). Using this data, they developed a prediction model including age, sex, and cardiovascular risk factors that was found to be highly accurate for the estimation of the pre-test probability of coronary artery disease.

CAD continues to be the leading cause of death in both men and women worldwide. However, CAD in women presents a unique and complex challenge to the clinicians. They often have larger symptom burden and more atypical presentation, yet lower rates of obstructive CAD compared to similarly aged men. Exercise ECG stress test has a very limited accuracy in women especially because of the resting ST-T wave changes, lower ECG voltage and certain hormonal factors. Similar to TMT, other common observations like electrocardiographic changes, myocardial perfusion defects, and regional wall motion abnormalities have limited predictive value in women undergoing evaluation for CAD. Furthermore, the use of CT coronary angiography is limited and expansive especially in a developing country like India. Coronary angiography (CAG) continues to be the gold standard investigation for diagnosis of obstructive CAD. But whether we can recommend it as a first line investigation to all the women presenting with chest pain, especially those with atypical chest pain- the answer is definitely ‘No’. This is because CAG is an invasive modality with inherent risk of complications. Although generally considered safe, death and procedural myocardial infarction can occur as complications in 0.1% patients. Vascular site complications are more frequently observed in as high as 8% patients depending upon the operator’s expertise, and occur more frequently in women. Therefore for all these reasons, it is imperative to identify the predictors of obstructive CAD in women before they undergo invasive coronary angiography.

With this aim, we conducted a prospective study in 674 consecutive female patients with suspected CAD, who underwent coronary angiography in our institute over a two years’ period (2015–2016). Risk factor profile and angiographic pattern of disease were recorded systematically in each patient. Obstructive CAD was defined as the presence of at least one major epicardial coronary artery with 50% or more narrowing of the luminal diameter. Patients were divided into 2 groups, with and without obstructive CAD, and were compared. Using multivariate logistic regression analysis, we were able to identify a few independent predictors/determinants of CAD in these patients. These included:

Age >55 years; OR(95%CI) = 3.41 (2.29–5.10)

Typical angina; OR(95%CI) = 15.75 (8.06–30.78)

Smoking; OR(95%CI) = 15.28 (6.27–37.21)

Diabetes; OR(95%CI) = 2.60 (1.68–4.03)

HDL-cholesterol <40 mg/dl; OR(95%CI) = 4.54 (2.71–7.57)

LDL-cholesterol >150 mg/dl; OR(95%CI) = 3.94 (1.95–7.96)

Where, [OR(95%CI)] = [Odds ratio (95% confidence interval)].

Interestingly, positive family history of premature CAD, post-menopausal status, presence of hypertension, overweight/obesity and a positive exercise ECG stress test did not independently determine the presence of obstructive CAD on multivariate analysis. However, sample size of 674 patients in our study was relatively small. Furthermore, we did not test the novel risk factors like serum Lipoprotein(a), high sensitivity C-Reactive protein, serum homocysteine, and serum triglycerides. We need larger prospective studies from different cultural, ethnic and social backgrounds to validate these results and identify the predictors of obstructive CAD in women. Identification of such predictors would help us in developing prediction models, like the one by Hongzeng Xu et al.. This would translate into avoidance of many un-necessary angiograms.