Usefulness of pulse pressure for the detection of extent and severity of coronary artery disease in type 2 diabetic patients with silent myocardial ischaemia at exercise stress test

Abstract

Among diabetic patients with silent myocardial ischaemia (SMI), those showing significant coronary stenosis have the worst prognosis [1]. Although the exercise stress test (EST) is quite well accepted as the first test for the screening of SMI, it is not a predictor of severity and/or extent of ischaemia or of significant coronary artery involvement. Therefore, in patients with SMI, an additional imaging test is undertaken as final proof of ischaemia [2]. The imaging test may also reveal the extent and severity of coronary artery disease (CAD), which allows the early identification of patients for whom revascularisation is appropriate [2]. Together with ST-segment depression, other parameters measured during exercise are evaluated to improve the predictive value for severity of CAD and the risk stratification in non-diabetic and diabetic subjects. Among these parameters, heart rate, with adjustment for ST-segment depression, is the best known [3]. Resting pulse pressure (RPP) is a strong predictor for cardiac events [4]. Increased large artery stiffness, a major determinant of RPP, is frequent in diabetes and may contribute to the development of CAD and ischaemia [5]. However, no data are currently available on the possible diagnostic usefulness of RPP for the detection of CAD in patients with type 2 diabetes. This cross-sectional study evaluated the usefulness of RPP in predicting severe CAD in patients with type 2 diabetes and SMI. The study design has been described in detail elsewhere [6]. Briefly, we recruited asymptomatic type 2 diabetic patients, without resting ECG signs of ischaemia, who were considered to be at “high risk” because of peripheral vascular disease (indicated by stenosis >40% at ultrasound Doppler) and/or two or more atherogenic factors (family history of myocardial infarction, smoking, urinary albumin excretion rate >20 μg/min, blood pressure >140/90 mmHg or antihypertensive therapy, dyslipidaemia [LDL cholesterol >3.36 mmol/L, HDL cholesterol 2.26 mmol/L or antidyslipidaemic therapy). Exclusion criteria were symptoms and/or ECG signs of ischaemia, age above 70 years, claudication below 400 m and left bundle branch block on resting ECG. SMI at EST was defined as horizontal or downsloping exercise-induced ST-segment depression being 1mm or more at 0.08 s after J point, with no angina. CAD was defined as stenosis being 70% or higher in at least one major epicardial artery at angiography. In accordance with the Helsinki Declaration, all patients were informed about the aim, risks, procedures and possible benefits of the study, and they all gave their consent. Among the 147 patients included in the study, 114 were EST negative (EST−) and 33 were EST positive (EST+) with asymptomatic ST-segment depression (i.e. had SMI). All 33 EST+ patients underwent coronary angiography. Angiography was also performed in 44 of the 114 EST− patients; the patients were randomly selected (using a table of random numbers). These patients showed no difference in clinical, metabolic and EST features compared with the 70 EST− patients who did not undergo angiography (data not shown). Twenty-three of the 33 patients with SMI (EST+) and eight of the 44 patients without SMI (EST−) had CAD. In the ten patients with SMI (EST+) who did S. Bacci (*) . M. Villella . A. Villella . A. Rauseo . T. Langialonga . V. Trischitta Cardiovascular and Endocrine Department, CSS Scientific Institute, Viale Cappuccini 1, 71013 San Giovanni Rotondo (FG), Italy e-mail: dnnwba@tin.it Tel.: +39-088-2410626 Fax: +39-088-2451637