Clinical Investigation Of New-onset Atrial Fibrillation In Acute Myocardial Infarction Patients

Part I:Predictors of new-onset atrial fibrillation after acute myocardial infarction:A prospective clinical observational studyObjective:To investigate the incidence and predictors of new-onset atrial fibrillation in acute myocardial infarction patients.Methods:From September2011to April2012a total of334consecutive patients with acute myocardial infarction (AMI) from our institute were included in this study. Among which165were ST-segment elevated myocardial infarction (STEMI) patients and169were non-ST segment elevated myocardial infarction (NSTEMI) Patients. During the hospital stay, patients were placed on continuous cardiac monitoring, their clinical records were reviewed, telemetry strips and ECGs were analyzed for atrial fibrillation (AF) up until the time of discharge from coronary care unit.Results:(1) New-onset AF was documented in9.6%(32/334) patients, with no significant difference between STEMI and NSTEMI patients(17/165Vs.15/169, P>0.05). Patients with AF were older(72.16±11.61years Vs.66.23±11.14years, P=0.009), shorter in hight(1.64±0.08m Vs.1.67±0.08m, P<0.05), and more often had increased admission heart rate(89.44±26.61bpm Vs.78.07±15.43bpm, P<0.001),hypertension(84.4%Vs.64.2%, P=0.029). There were no significant differences between Af and non-AF patients regarding admission blood pressure, AMI type, history of diabetes and dyslipidemia and previous PCI.Compared with non-AF patients, AF patients had significant higher Crusade(P=0.002) and CHA2DS-VASc (P=0.009) score; Regarding laboratory tests, AF patients often had higher WBC(P=0.008),RDWcv(P=0.037) and peak cTnT(P=0.029) than those without the arrhythmia. Additionally, eGFR were significant decreased in patients with AF(P=0.002) compared with non-AF patients. However, plasma NT-proBNP levels within24hours of admission[2295.00(1263.25-4694.50)pg/mL Vs.653.95(193.85-2100.00)pg/mL, P<0.001] and peak NT-proBNP levels during the hospital stay [(3915.00(2242.00-6550.50)pg/mL Vs.1184.00(435.28-3134.25)pg/mL, P<0.001] were significantly increased in patients with AF; Echocardiographic Assessments showed that AF patients often had larger left atrial diameter when compared with those who had no AF. There were no significant differences regarding other laboratory results and echocardiography measurements; Fewer Patients with AF received PCI therapy compared with those without the arrhythmia. There were no significant differences regarding number of diseased coronary vessels, TIMI score of coronary artery blood flow at the end the revascularization procedure and medication treatment strategies.(2)Multivariate logistic regression analysis showed that increased admission heart rate (OR1.024,95%CI1.003-1.046, P=0.028), enlarged left atrial diameter (OR1.091,95%CI1.008-1.184, P=0.031), elevated admission NT-proBNP levels (OR1.988,95%CI1.029-3.845, P=0.041), and peak NT-proBNP levels (OR2.745,95%CI1.326-5.683, P=0.007) were the only independent risk factors for the development of new-onset AF in hospitalized AMI patients.(3) Receiver operating characteristics (ROC) analysis revealed a plasma level of NT-proBNP=1100pg/mL as the best cut-off value for new-onset AF prediction in AMI patients, with a sensitivity of81.2%and specificity of61.3%. The incidence of new-onset AF in high NT-proBNP patients was significantly higher when compared with patients with lower levels of NT-proBNP (26/144,18.1%Vs.6/190,3.2%, P<0.001).Conclusion:Increased admission heart rate, enlarged left atrial diameter, elevated admission plasma NT-proBNP levels and peak NT-proBNP levels during hospital stay are strong independent predictors of developing new-onset AF in hospitalized AMI patients. NT-proBNP guided therapy may have a beneficial role in the prophylactic therapy that aimed to reduce the incidence of new-onset AF. Part Ⅱ:Clinical investitation on hemodynamic charaterisitics, neurohormonal and inflammatory activation and short-term outcomes of acute myocardial infarction patients with new-onset atrial fibrillationObjective:To investigate the hemodynamic characteristics, neurohormonal and inflammatory activation and short-term outcomes of myocardial infarction patients with new-onse atrial fibrillation.Methods:From September2011to April2012fifty nine consecutive patients with acute myocardial infarction from our institute were included. Among which25patients developed new-onset atrial fibrillation during their hospitalization, and34patients without the arrhythmia. During the hospital stay, patients were placed on continuous cardiac hemodynamic monitoring for24hours. Blood tests for angiotensin II, IL-6, TNF-a, Renin, Myeloperoxidase (MPO) and Osteoprotegerin(OPG) were performed on the first and third day after admission. A ninety day clinical follow-up for major adverse cardiovascular events defined as the combined end point of definite or suspected cardiac death, non-fatal myocardial infarction, readmission, target lesion failure and stroke(fatal or non-fatal) was performed for all the patients.Results:(1) patients with new-onset atrial fibrillation had no significant differences regarding cardiac output, cardiac index, cardiac power and stroke volume. However, stroke volume variation was significantly increased in AF patients(15±2.8%Vs.11.9±2.9%, P<0.001), whereas peak aortic flow was significantly decreased. No significant differences were found regarding other hemodynamic parameters between the two groups;(2) patients with new-onset atrial fibrillation had higher plasma levels of angiotensin Ⅱ, TNF-α, MPO and NT-proBNP when compared with patients in sinus rhythm. Additionally, AF patients had higher level of OPN, but the difference did not reach statistic significancy; plasma levels of IL-6, renine and aldosterone were not significantly different between the two groups;(3) during the ninety day follow-up, patients from the New-onset AF group had significant worse outcomes when compared the patients without the arrhythmia; Kaplan-meier survival analysis showed a significantly decreased events free survival rate in the atrial fibrillation group.Conclusion:(1) Stroke volume variations were the most important changes of hemodynamic characteristics of myocardial infarction patients with new-onset atrial fibrillation;(2) the levels of neurohormonal and inflammatory activation were significantly higher among new-onset atrial fibrillation group;(3) the onset of new atrial fibrillation in myocardial patients was independent predictor of shrot-term poor outcomes. Part III:Plasma levels of NT-proBNP predicts new-onset atrial fibrillation following acute myocardial infarction Objective:To investigate the predictive value of N terminal pro B type natriuretic peptide(NT-proBNP) for the occurrence of new-onset atrial fibrillation(AF) in patient with acute myocardial infarction(AMI).Methods:A total of293patients diagnosed with AMI between January2008to December2010in Zhongshan Hospital Fudan University were studied. The patients were divided into two groups by the presence or absence of AF, NT-proBNP was measured within24hours after admission. Receiver operating characteristic analysis was performed to identify the most useful NT-proBNP cut-off level for the prediction of AF, the patients were divided into high NT-proBNP group(NT-proBNP>613pg/mL, n=188) and low NT-proBNP group(NT-proBNP<613pg/mL, n=105) accordingly.Results:(1) The incidence of new-onset AF in AMI patients was14.7%, with no significant difference between ST-segment elevation myocardial infarction(STEMI) and non-ST elevation myocardial infarction(NSTEMI) patients;(2) Patients with AF were older, had more often lower left ventricular ejection fraction, anemia and renal insufficiency;(3) AF occurred more frequently in high NT-proBNP group(42/188,22.3%) than in low NT-proBNP patients(1/105,1%),(P<0.001);(4) Multivariate regression analysis showed that elevated plasma NT-proBNP levels was an strong predictor for new-onset AF after AMI(OR4.918,95%CI1.662-14.549, P=0.004).Conclusion:Elevated plasma NT-proBNP levels independently predict new-onset AF in hospitalized AMI patients, NT-proBNP guided therapy may have a beneficial role in the prophylactic therapy that aimed to reduce the incidence of new-onset AF.