The impact of diabetes mellitus on improvement of resting rate pressure product in patients with refractory angina undergone external counter pulsation
Authors: Yasmin A , Radi B , Ambari A M , Dwiputra B 
Published: January 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
The management of coronary artery disease (CAD) has developed significantly in the last few decades. One of the therapeutic modalities that could be considered to patients with refractory angina caused by CAD is external counter pulsation (ECP). Rate pressure product (RPP) is a determinant of cardiac oxygen consumption and heart workload. It is a simple parameter that could be calculated easily by multiplying systolic blood pressure and heart rate. Increased resting RPP is associated with higher myocardial oxygen consumption and decreased cardiac efficiency. Studies that discuss factors that influence the decrease of resting RPP due to ECP procedure as a possible mechanism underlying the improvement of clinical symptoms in patients with refractory angina are still very limited.

Purpose
This study aimed to determine the impact of diabetes mellitus (DM) as one of most common risk factors for complex CAD and refractory angina on the decremental of resting RPP in refractory angina patients who have undergone standard 35 sessions of ECP.

Methods
This is a cohort retrospective study that collected data from registry of all patients who have completed 35 sessions of ECP procedures from 2018 until 2021. We compared the improvement of resting RPP after program completion and evaluated the effect of DM and blood glucose levels on the difference in resting RPP. Statistical test was performed by SPSS software for windows.

Results
A total of 16 patients were enrolled in this study with mean age of 65.4 years old. Subjects in this study were predominantly male (87.5%) and most of the subjects (68.8%) were diagnosed with CAD/3-vessels disease (3VD). The main risk factors found in the subjects were hypertension (75%) and DM (62.5%). All subjects underwent random blood sugar examination before starting ECP procedure with mean 122.7 mg/dL. Paired samples T-test analysis found that there was a decrease in resting RPP in subjects after undergoing ECP compared to before the procedure (7046.1 ± 1515.3 vs 8572.5 ± 1915.7; p-value &lt;0.001). Independent samples T-test showed that the presence of DM reduced the mean decrease of resting RPP in study subjects (1034.8 ± 1122.2 vs 2345.7 ± 1167.5; p-value 0.043). Pearson correlation analysis showed that there was no significant correlation between blood sugar levels and decrease in resting RPP after ECP completion in study subjects (correlation coefficient -0.049; p-value: 0.869).

Conclusion
Standard 35 ECP sessions could decrease resting RPP in refractory angina patients. The improvements may contribute to the clinical benefit of ECP. However, the presence of DM can reduce the effectiveness of ECP in improving resting RPP, regardless of the blood sugar levels. These findings were probably related to cardiovascular autonomic neuropathy that were commonly found among diabetics. Further research is needed to elucidate the exact underlying mechanisms of these outcomes.