Double Product as a Predictor of Coronary Artery Disease in Males with Normal Blood Pressure

Aim: This study investigates whether in males with normal blood pressure that underwent exercise stress test Double Product (DB) or Double Product Ratios to workload (DPR) are self-sufficient in predicting the presence of coronary artery disease (CAD). Method: 78 male patients with normal blood pressure went through bicycle exercise stress test (EST) and within four weeks they underwent coronary angiography. 34 of them resulted with normal coronary arteries and 44 of them were diagnosed with one or multiple vessel CAD. Pressure rate double product was calculated in rest, in the first stage of the exercise test, in the peak of exercise, and also in the second, fourth, and sixth minutes of recovery of the stress test. Also, the ratios of pressure rate double product with the workload, which reflects the relative growth of double product to the workload, were calculated. The results were compared between the two groups, the one with normal coronary arteries, and those with abnormal coronary angiography. Results: DP in rest and in the first stage of the exercise are not significantly different for normotensive males with or without CAD, while the peak DB value of the exercise, as well as the econd and sixth minutes of the recovery are significantly lower for the group of patients with CAD. The starting peak workloads were significantly lower in the patients' group with CAD (p=0.0002 and p 0.0001). On the other hand, the double product to workload ratio at the first stage was significantly lower in males with normal blood pressure and CAD. Significant lower DPR are detected also in the fourth and sixth minutes of recovery. Conclusion: The values of DP in the peak exercise and at the second and sixth minutes of the recovery phase are significantly lower in normotensive males with abnormal coronary angiography compared to those with normal coronary arteries, and these findings can be used to detect the presence of CAD despite the ECG changes and they are not affected by the baseline characteristics of the patients. The ratios between DP and workload at the first stage, and in the fourth and sixth minutes of recovery are significantly lower in normotensive male patients with coronary artery disease compared to those without CAD and can be independent predictive parameters for the disease.