The Correlative Research About Acquired Long QT Syndrome And Left Ventricular Hypertrophy In Patients With Essential Hypertension

Objectives: Sudden cardiac death(SCD)is an enormous public health problem and constituting 50% of over cardiovascular mortality.Several studies have shown the common concomitant presence of prolonged QT interval and LVH.Essential hypertension(EHTN)is the most common cardiovascular disease that can lead to the LVH.However there are limited data on the prevalence of QT prolongation among patients with EHTN-LVH.The aim of this study is to investigate the correlation between EHTN-LVH and QT prolongation.Methods: This is a retrospective study.Patients diagnosed with EHTN-LVH who have been hospitalized in the first affiliated hospital of Dalian medical university from September 2013 to August 2014 enrolled in our study.All study subjects met the ECG LVH criteria defined by Sokolow-Lyon Voltage,Cornell Voltage or Cornell Product.ECGs were retrieved from an institutional-wide MUSE system.Clinical information of study subjects was obtained from the electronic medical records(EMR).Exclusion criteria:(1)Factors that prevent accurate QT measurement or QTc calculation such as atrial fibrillation/flutter,atrial tachycardia,frequent premature ventricular/atrial contractions,QRS duration >120 ms(complete left/right bundle branch block,pacing rhythm,aberrant ventricular conduction),heart rate(HR)> 100 beats per minute,etc;(2)LVH associated with valvular heart disease,secondary hypertension,or cardiomyopathies;(3)QTc prolongation due to any known factors or diagnoses that could prolong the QT interval,such as hypokalemia,hypocalcaemia,stroke,chronic kidney disease and use of QT-prolonging drugs,etc.ECG parameters including HR,PR interval,QRS duration/amplitude,QT interval(QTc by Bazett's)and presence of ST depression(?0.05 m V)and T wave(ST-T)abnormalities were evaluated.If the subjects have a Holter data,parameters including SDNN,SDANN,r MSSD,PNN50,LF,HF were recorded to evaluate the heart rate variability(HRV).The statistical software SPSS 17.0 were used for all analyses.Results: 1.572 subjects [age 63(54,72)years,378(66%)Male] met the inclusion criteria.Among them 146(25.5%)patients presented with QTc prolongation associated with EHTN-LVH,markedly prolonged QT prolongation(QTc ?500 ms)were seen in 1.6%(9/572),moderate prolongation of QTc(470 to 499ms)in 7.0%(40/572),and borderline prolongation of QTc(450 to 469 ms)in 16.9%(97/572),respectively.Female is predominant QTc prolongation,especially in those showing longer QT intervals.2.Compared to the patients with a normal QT interval,QTc prolongation subjects displayed a greater valve of Cornell Product [2193(1549,2820)vs 1974(1321,2654)mm*ms,P=0.008],and a faster HR [72(65,80)vs 66(59,74)bpm,P=0.00],respectively.More patients in QTc prolongation group had ST-T abnormalities(40% vs 26%,P <0.01).Binary logistic regression analysis revealed that ST-T abnormalities,HR and female sex were independent predictors of QTc prolongation in patients with EHTN-LVH.3.194 patients have a Holter dada.Among them,77 patients(44%)had a prolonged QTc.Compared to the patients with normal QTc.QTc prolongation subjects had significantly decreased SDNN,r MSSD,PNN50,HF and increased LF(P<0.05),indicating the QTc prolongation subjects have a decreased heart rate variability.Conclusion: 1.The prevalence of QTc prolongation is high in patients with EHTN-LVH,indicating EHTN-LVH is likely a most common cause of ALQTS in general population.2.Patients with QTc prolongation due to EHTN-LVH have a higher QRS amplitude.This findings suggest repolarization abnormalities secondary to the increased ventricular mass may be the major underlying cause of QT prolongation in EHTN-LVH.3.QTc prolongation group had a faster HR and decreased heart rate variability,indicating they had a increased excitability of the sympathetic nervous system.