Int J Clin Exp Med 2018;11(6):6106-6112 www.ijcem.com /ISSN:1940-5901/IJCEM0064109 Original Article Cardiac characteristics in the premature ventricular contraction patients with or without ventricular tachycardia Yafen Su1*, Meng Xia2,3*, Junxian Cao2, Qianping Gao2 1Ambulatory Electrocardiogram Room, The First Affiliated Hospital of Harbin Medical University, China; 2Unit of Cardiology, The First Affiliated Hospital of Harbin Medical University, China; 3Unit of Cardiology, Liaoyang Central Hospital, China. *Equal contributors. Received August 21, 2017; Accepted March 22, 2018; Epub June 15, 2018; Published June 30, 2018 Abstract: Background/Aims: Frequent (sustained) premature ventricular contractions (PVCs) lead to ventricu- lar tachycardia (VT), which triggers ventricular fibrillation and sudden cardiac death. The cardiac characteristics and risk prediction in frequent/sustained PVC patients with or without VT have been still in need of investigation. Methods: The data from patients with frequent PVCs via 24 h ambulatory electrocardiogram (ECG) monitor were collected at the Department of Cardiology in the First Affiliated Hospital of Harbin Medical University from January 1, 2012 to August 31, 2015. Total 342 patients were grouped into VT group (n=136) and Non-VT group (n=206) based on the presence or absence of VT. Cardiac functional examination and blood tests were carried out on the second day of admission. Independent risk factors related to the occurrence of VT were identified. The receiver operating characteristic (ROC) curves was established to evaluate the accuracy of the risk factors and VT. Results: The baseline characteristics were similar between the two groups. The blood potassium, extensive PVC burden, left ventricular ejection fraction (LVEF), PVC couplets, and alcohol consumption were associated with the occurrence of VT. Of them, the occurrence of PVC couplets was an independent high risk factor for the development of VT in the patients with frequent PVCs. Based on the weight of these risk factors for the occurrence of VT, a simple scoring method for VT prediction was set up in this study. The area under curve (AUC) for receiver operating characteristic (ROC) curves of the new scores resulted from the scoring method was 0.8874, indicating a valuable predictor for VT occurrence. Conclusion: The PVC couplets is an independent high risk factor for the development of VT in the patients with frequent PVCs. Keywords: Sudden cardiac death, ventricular tachycardia, premature ventricular contractions, left ventricular ejec- tion fraction, electrocardiogram Introduction structural cardiopathy such as coronary artery disease (CAD), aortic stenosis, cardiomyopathy The premature ventricular contractions (PVCs) and electrolyte problem. The electrical events are early depolarization of the myocardium of the heart detected with the ECG allow the caused by an electrical impulse or ectopic PVC to be easily distinguished from a normal rhythm from any part of the ventricles, includ- heart beat. PVCs can be observed in both ing the ventricular septum, before the sinoatrial healthy people and patients with or without impulse has reached the ventricles. According structural cardiopathy [2, 3]. Frequent PVCs, to the frequency of ventricular premature beats also called sustained PVCs, is a risk factor that (VPB), PVCs can be divided into sporadic and leads to ventricular tachycardia. frequent [1]. Sporadic PVCs are, also called functional premature beats, defined as less Ventricular tachycardia (VT) is the myocardial than 6 pules/min, which can occur in healthy arrhythmias under His bundle branch and myo- people; while frequent PVCs, defined as more cardial conduction fiber. Wellens [4] defined VT than 6 pules/min, can occur in patients with as more than 100 beats/min, and three or more Cardiac characteristics in the premature ventricular contractions patients Table 1. Basic characteristics and medical history of the two First Affiliated Hospital of Harbin groups (n (%)) Medical University from January 1, Parameter VT (n=136) Non-VT (n=206) P 2012 to August 31, 2015. Inclusion criteria for the study were: 1) with Ages (years), mean ± SD 58.10 ± 13.50 56.44 ± 15.17 0.300 a more than 30-beat of ventricular Male 70 (51.47) 83 (40.29) 0.042 premature per hour; 2) the frequ- Smoking 44 (32.35) 56 (27.18) 0.304 ency of PVCs ranged from 746 to Drinking alcohol 38 (27.94) 32 (15.53) 0.005 47083 per 24 h. Exclusion criteria CAD 54 (39.71) 94 (45.63) 0.279 were: 1) pulmonary heart disease, OMI 11 (8.09) 7 (3.40) 0.057 severe dysfunction of kidney and Hypertension 45 (33.09) 83 (40.29) 0.178 liver, rheumatic disease, and tu- Diabetes 20 (14.71) 24 (11.65) 0.409 mor: 2) receiving the treatment with digitalis, quinidine and tricyclic DCM 48 (35.29) 11 (5.34) < 0.001 antidepressant. The 342 patients Alcoholic myocardiopathy 5 (3.68) 0 (0.00) 0.021 were assigned into VT group (136) ICM 18 (13.24) 6 (2.91) < 0.001 and non-VT group (206) based on Valvular heart disease 4 (2.94) 4 (1.94) 0.816 the presence or absence of VT. The HCM 1 (0.74) 0 (0.00) 0.398 study was approved by the Ethical Tachycardiomyopathy 1 (0.74) 0 (0.00) 0.398 Committee of Institutional Review VT: ventricular tachycardia, CAD: coronary artery disease, OMI: old myocar- Board at the First Affiliated Hospital dial infarction, DCM: Dilated Cardiomyopathy, ICM: ischemic cardiomyopathy, of Harbin Medical University. HCM: hypertrophic cardiomyopathy. Information collection consecutive spontaneous PVCs. Six or more The baseline information was collected at ad- rapid ventricular beats (frequency > 100/min) mission, including gender, age, blood pressure, are considered as persistent VT (longer than and heart rate. Medical history included hyper- 30 seconds), while less than 6 beats as non- tension, coronary artery disease (CAD), dilated persistent VT (episodes less than 30 seconds). cardiomyopathy (DCM), ischemic cardiomyopa- Persistent VT is very dangerous, as it can trig- thy (ICM), smoking and drinking (alcohol). Heart ger ventricular fibrillation and sudden cardiac function examination and blood tests were car- death. ried out on the second day of hospitalization. Measurements of LVEF, left ventricular end-dia- Although clinical and electrophysiological stud- stolic diameter (LVEDD), inter-ventricular septal ies have featured the different initiation pat- thickness (IVST) and left ventricular posterior terns of VT [5, 6], studies on the cardiac char- wall thickness (LVPWT) were conducted by a acteristics in the PVC patients with or without cardiology specialist through Vivid Echocardio- VT have not been reported. Therefore, this stu- gram. The left ventricular muscle mass (LVM) dy was designed to explore the predictors for was calculated according to the Devereux for- the PVC patients who may develop into VT, and mula. Ambulatory monitoring was initiated in an evaluating method based on the weights the afternoon following the hospitalization. An of these predictors on VT. Due to a higher mor- electrocardiogram specialist was responsible bidity of cardiac diseases in the northeastern for recoding and analyzing the 24 h ambulatory part of China, where there have been a longer ECG monitoring results. The total heart beats, winter and the unhealthy diet, all patients in the frequency of PVCs, PVC burden, PVC couplets, current study were from one hospital in Harbin, polymorphic and multifocal PVCs, and VT were a representative city in the northeast of China. recorded. Patients and methods Statistical analysis Patients Normally distributed variables were compared with Student’s t-test, while non-normally distrib- This was a retrospective study. The medical uted variables were compared with Wilcoxon records were collected from 342 patients with two sample test. Qualitative data were com- frequent PVCs detected via 24 h ambulatory pared by X2 test. The receiver operating charac- ECG monitoring at Department of Cardiology in teristic (ROC) curves were drawn with the proc 6107 Int J Clin Exp Med 2018;11(6):6106-6112 Cardiac characteristics in the premature ventricular contractions patients Table 2. Comparison of laboratory blood examination in the two with SAS 9.3 software and the groups (mean ± SD) statistical significance was set at VT group Non-VT group P < 0.05 for two-tailed tests. Parameter P (n=136) (n=206) Results Glucose (mmol/L) 5.80 ± 2.28 5.30 ± 1.13 0.373 Cholesterol (mmol/L) 4.40 ± 1.13 4.69 ± 1.01 0.016 Comparisons of baseline charac- TG (mmol/L) 1.50 ± 1.02 1.58 ± 0.83 0.044 teristics and blood test results LDL (mmol/L) 3.01 ± 0.93 3.18 ± 0.89 0.065 K+ (mmol/L) 4.21 ± 0.44 4.05 ± 0.38 0.001 Of the 342 enrolled patients, 130 Mg2+ (mmol/L) 0.85 ± 0.08 0.87 ± 0.09 0.076 patients (38.0%) had no structural Ca2+ (mmol/L) 2.30 ± 0.14 2.31 ± 0.16 0.093 heart diseases, while 212 (62.0%) TNI (ng/mL) 0.10 ± 0.81 0.01 ± 0.08 < 0.001 did, including CAD, DCM, ICM, CKMB (u/L) 14.39 ± 13.25 11.71 ± 10.20 0.032 hypertension and valvular heart disease. The baseline characteris- Fibrinogen (g/L) 2.71 ± 0.76 2.68 ± 0.70 0.626 tics of the patients were shown in UA (umol/L) 361.8 ± 143.2 308.7 ± 87.94 0.003 Table 1. No significant differences VT: ventricular tachycardia, TG: triglyceride, LDL: low densitylipoproteins, TNI: in age, smoking history, systolic troponinI, CKMB: creatinekinase-MB, UA: uricacid. blood pressure (SBP), and diastol- ic blood pressure (DBP) were ob- Table 3. Cardiac parameters by Doppler echocardiography and served between the two groups. ambulatory electrocardiogram (mean ± SD) However, the ratios of patients with DCM (35.29% vs 5.34%), ICM Parameter VT (n=136) Non-VT (n=206) P (13.24% vs 2.91%), alcohol drink- VPCs (beats/24 h) 11628 ± 9227 8440 ± 8520 < 0.001 ing history (27.94% vs 15.53%), Heart rates (beats/24 h) 98662 ± 15947 104732 ± 64126 0.156 and gender (male/female ratio) LVPWT (mm) 9.13 ± 1.04 9.17 ± 1.05 0.797 (51.47% vs 40.29%) were signifi- IVST (mm) 9.35 ± 1.33 9.26 ± 1.23 0.714 cantly higher in VT group than that LVEDD (mm) 59.00 ± 12.07 49.16 ± 6.67 < 0.001 in non-VT group (P < 0.05).