Serial changes in plasma brain natriuretic peptide in patients treated with conventional stenting or direct stenting: a comparative study

Abstract

11 ABSTRACT Background.Brain natriuretic peptide(BNP) is a neurohormone secreted predominantly from the ventricular myocardium in response to stretch due to volume and pressure overload.BNP level has also been shown to increase transiently after uncomplicated percutaneous transluminal coronary angioplasty(PTCA), even when the intracardiac pressures remain normal. However there is no data on serial changes of BNP in patients with documented coronary artery disease undergoing stent implantation with direct stenting(DS) without balloon predilatation and conventional stenting (CS) with balloon predilatation method. Objectives: Serial changes of BNP along with other cardiac markers like Troponin I and CK-MB in patients undergoing stent implantation with DS or CS to evaluate the incidence of minor myocardial injury possibly caused by stent implantation and its subsequent effect on left ventricular function is the primary aim and objective of our study. Mefhods:The study population consisted of 40 patients with single vessel coronary artey disease who underwent elective stent implantation as a treatment procedure.The patients were divided into two groups ;Group I (n=20) with mean age 57.9+10.1 yrs,85%male,15% female, comprised of the patients treated with direct coronary stenting and Group II (n=20),with mean age 57.9±8.0 yrs,75%male and 25% female,treated with conventional stenting. For both group of patients, blood samples for Troponin I and CK-MB measurement were obtained at baseline, just after the intervention procedure, 6 hours after and also 12 hours after stenting.Plasma BNP levels for every patients were also measured at baseline,6 hours and 12 hours after stenting.The serial changes in troponin I,CK-MB and BNP were analysed in each group and in between two groups.Ill Resu/fs:The serial changes in CKMB at baseline, just after the stent implantation,6 hours after procedure and 12 hours after procedure were not statistically significant in both groups.Troponin I level in Group I with direct stenting did not show any changes statistically significant at different time intervals, but in Group II with conventional stenting there was a significant increase in Troponin I level 12 hours after the procedure (baseline 0.033 +_ 0.028 ng/ml vs 0.084+_ 0.085 ng/ml; p <0.05). Considering BNP level at different time interval in Group I with direct stenting, there was a decrease in BNP level with statistical significance both in base line vs. 6 hours after procedure and baseline vs 12 hours after procedure (105.2+_ 73.7 pg/ml vs 81.3+_67.1 pg/ml ; p <0.05 and 105.2+_73.7 pg/ml vs 89.9+_62.3pg/ml ; p<0.05 respectively).Group II patients with conventional stenting did not show any significant serial changes in BNP levels though there was a trend towards a small nonsignificant increase in BNP levels. Conclusion: With direct stenting BNP levels decreased significantly with no significant change in Troponin I level, while with conventional stenting BNP levels tend to rise and Troponin I levels incresed significantly. These results favouring direct stenting, may be related to lowering of minor myocardial injury caused by stenting and an overall improvement of ventricular function with effective resolution of the stenotic lesions without any acute complication at minute level. Key words: Brain natriuretic peptide, Direct stenting, Conventional stenting.