INTRODUCTION
Atrial fibrillation (AF) is one of the most common forms of cardiac arrhythmia that is associated with not only increased mortality but also the progression of heart failure (HF) and an increased frequency of HF hospitalisation.1 2 The incidence and prevalence of AF are expected to double in the next 20 years, with corresponding increases in the mortality rate and medical cost.3 4Some risk factors such as old age and combined coronary artery disease (CAD) are known predictors of adverse outcomes in patients with AF.5 In the setting of sinus rhythm, both systolic and diastolic dysfunctions are well-known risk factors of adverse outcomes such as mortality and HF hospitalisation.6 7 However, data regarding the relationship between diastolic dysfunction and adverse cardiac events in patients with AF are insufficient. Moreover, in the setting of chronic AF, prediction of the status of diastolic function is exceedingly difficult.8 During progression of diastolic dysfunction, elevated left ventricular end-diastolic pressure (LVEDP) reflects the extent of diastolic dysfunction.9 10 However, no studies have evaluated the relationship between elevated LVEDP and adverse cardiac outcomes in patients with chronic AF. Therefore, the aim of the present study was to clarify the prognostic significance of systolic and diastolic dysfunctions in patients with chronic persistent AF by evaluating the relationship of systolic dysfunction as well as elevated LVEDP, which can reflect the extent of diastolic dysfunction, with the 3-year clinical outcomes.
METHODS
Study design and population
We evaluated data for 114 consecutive patients with chronic AF who underwent measurement of LVEDP at our hospital between 1 March 2011 and 31 December 2014. All patients presented with symptoms such as unexplained dyspnea, chest discomfort, and chest pain and underwent coronary angiography after providing informed consent. We excluded patients with paroxysmal AF, mitral stenosis, rheumatic disease, severe mitral regurgitation, moderate to severe aortic stenosis, severe aortic regurgitation, prosthetic valve disease and severe tricuspid regurgitation, and/or right ventricular dysfunction. The included patients were divided into two groups according to their left ventricular ejection fraction (LVEF): LVEF < 50 (n = 24; REF group) and LVEF ≥ 50 (n = 90; PEF group). For evaluation of the outcomes with regard to diastolic dysfunction, the PEF group was further divided into two subgroups according to the left ventricular end-diastolic filling pressure (LVEDP): LVEDP >15 mmHg (n = 38) and LVEDP ≤15 mmHg (n = 52). Clinical data were obtained by face-to-face interviews in the outpatient clinic and/or telephone interviews, a complete review of electronic medical records, physical examinations, history taking, laboratory examinations, echocardiography, and haemodynamic measurements.
This single-centre study was performed at a university hospital, and the protocol was approved by the institutional review (IRB) board of the hospital (IRB approval number: 2015-14). All patients or their legal guardians were provided a thorough written and verbal explanation of the study procedures, following which they gave written consent for participation in the study.
Echocardiography and haemodynamic measurements
A single experienced physician performed baseline transthoracic echocardiography (TTE) with the patient in the left lateral decubitus position within 24 h before the measurement of LVEDP using a GE Vivid 7 device equipped with M4S transducers (GE Medical, Milwaukee, USA). All measured images were digitally recorded for subsequent analysis. Measured echocardiographic parameters included the ejection fraction (EF), left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), left atrial volume, degree of mitral and aortic regurgitation, and stenosis. LVEF was calculated using the biplane modified Simpson’s method.11 Echocardiographic Doppler parameters were also measured and stored. The transmitral flow, mitral annular motion velocity, E-wave deceleration time (DT), and propagation velocity (Vp) were recorded for five consecutive cardiac cycles, and the results were averaged. LVEDP and the minimal LV filling pressure were measured using a 5-Fr pigtail catheter positioned at the left ventricle and aorta during coronary angiography. LVEDP was measured at the Z-point, which is identified on the left ventricular pressure traceas the point at which the slope of the ventricular pressure upstroke changes, and averaged over 10 consecutive beats.12 An investigator blinded to the echocardiographic data acquired the pressure values.
Clinical outcomes
The 3-year clinical outcomes were evaluated and compared between the REF and PEF groups andthe two LVEDP groups. Clinical outcomes, including the mortality rate; incidences of stroke, AF with rapid ventricular rhythm (RVR), and bleeding; and rate of HF hospitalisation, were recorded for all patients. RVR was defined as a ventricular response of >100 beats/min at presentation. Bleeding referred to major bleeding that was fatal or intracranial or affected another critical anatomical site, or overt bleeding causing a decrease in haemoglobin of ≥20 g/L or necessitating transfusion of ≥2 units of erythrocytes.
Data analyses
Intergroup differences in continuous variables, presented as means ± standard deviations, were evaluated by Student’s t-test. Differences in categorical variables, expressed as numbers and percentages,were analysed using the χ2test or Fisher’s exact test as appropriate. Kaplan–Meier curves were generated for determination of the time-dependent HF hospitalisation rate, with comparisons performed using the log-rank test. Cox proportional hazards models were used to estimate the risk factors for HF hospitalisation during the 3-year period, with calculation of hazard ratios (HRs) and 95% confidence intervals (95% CIs). A two-sided p-value of <0.05 was considered statistically significant in all tests. All statistical analyses were performed using SPSS 20 (IBM SPSS., Chicago, IL, USA).
RESULTS