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QRS/T-wave and calcium alternans in a type I diabetic mouse model for spontaneous postmyocardial infarction ventricular tachycardia: A mechanism for the antiarrhythmic effect of statins.

ABSTRACT: The incidence of sudden arrhythmic death is markedly increased in diabetics.The purpose of this study was to develop a mouse model for postmyocardial infarction (post-MI) ventricular tachycardia (VT) in the diabetic heart and determine the mechanism of an antiarrhythmic effect of statins.ECG transmitters were implanted in wild-type (WT), placebo, and pravastatin-treated type I diabetic Akita mice. MIs were induced by coronary ligation, and Ca2+ transients were studied by optical mapping, and Ca2+ transients and sparks in left ventricular myocytes (VM) by the Ionoptix system and confocal microscopy.Burst pacing of Akita mouse hearts resulted in rate-related QRS/T-wave alternans, which was attenuated in pravastatin-treated mice. Post-MI Akita mice developed QRS/T-wave alternans and VT at 2820 ± 879 beats per mouse, which decreased to 343 ± 115 in pravastatin-treated mice (n = 13, P <.05). Optical mapping demonstrated pacing-induced VT originating in the peri-infarction zone and Ca2+ alternans, both attenuated in hearts of statin-treated mice. Akita VM displayed Ca2+ alternans, and triggered activity as well as increased Ca2+ transient decay time (Tau), Ca2+ sparks, and cytosolic Ca2+ and decreased SR Ca2+ stores all of which were in part reversed in cells from statin treated mice. Homogenates of Akita ventricles demonstrated decreased SERCA2a/PLB ratio and increased ratio of protein phosphatase (PP-1) to the PP-1 inhibitor PPI-1 which were reversed in homogenates of pravastatin-treated Akita mice.Pravastatin decreased the incidence of post-MI VT and Ca2+ alternans in Akita mouse hearts in part by revering abnormalities of Ca2+ handling via the PP-1/PPI-1 pathway.

SUBMITTER: Jin H

PROVIDER: S-EPMC5713915 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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QRS/T-wave and calcium alternans in a type I diabetic mouse model for spontaneous postmyocardial infarction ventricular tachycardia: A mechanism for the antiarrhythmic effect of statins.

Jin Hongwei H Welzig Charles M CM Aronovitz Mark M Noubary Farzad F Blanton Robert R Wang Bo B Rajab Mohammad M Albano Alfred A Link Mark S MS Noujaim Sami F SF Park Ho-Jin HJ Galper Jonas B JB

Heart rhythm 20170515 9

<h4>Background</h4>The incidence of sudden arrhythmic death is markedly increased in diabetics.<h4>Objective</h4>The purpose of this study was to develop a mouse model for postmyocardial infarction (post-MI) ventricular tachycardia (VT) in the diabetic heart and determine the mechanism of an antiarrhythmic effect of statins.<h4>Methods</h4>ECG transmitters were implanted in wild-type (WT), placebo, and pravastatin-treated type I diabetic Akita mice. MIs were induced by coronary ligation, and Ca< ...[more]

PMID: 28522367

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Project description:Background Unlike T-wave alternans (TWA), the relation between QRS alternans (QRSA) and ventricular arrhythmia (VA) risk has not been evaluated in hypertrophic cardiomyopathy (HCM). We assessed microvolt QRSA/TWA in relation to HCM risk factors and late VA outcomes in HCM. Methods and Results Prospectively enrolled patients with HCM (n=130) with prophylactic implantable cardioverter-defibrillators underwent digital 12-lead ECG recordings during ventricular pacing (100-120 beats/min). QRSA/TWA was quantified using the spectral method. Patients were categorized as QRSA+ and/or TWA+ if sustained alternans was present in ≥2 precordial leads. The VA end point was appropriate implantable cardioverter-defibrillator therapy over 5 years of follow-up. QRSA+ and TWA+ occurred together in 28% of patients and alone in 7% and 7% of patients, respectively. QRSA magnitude increased with pacing rate (1.9±0.6 versus 6.2±2.0 µV; P=0.006). Left ventricular thickness was greater in QRSA+ than in QRSA- patients (22±7 versus 20±6 mm; P=0.035). Over 5 years follow-up, 17% of patients had VA. The annual VA rate was greater in QRSA+ versus QRSA- patients (5.8% versus 2.0%; P=0.006), with the QRSA+/TWA- subgroup having the greatest rate (13.3% versus 2.6%; P<0.001). In those with <2 risk factors, QRSA- patients had a low annual VA rate compared QRSA+ patients (0.58% versus 7.1%; P=0.001). Separate Cox models revealed QRSA+ (hazard ratio [HR], 2.9 [95% CI, 1.2-7.0]; P=0.019) and QRSA+/TWA- (HR, 7.9 [95% CI, 2.9-21.7]; P<0.001) as the most significant VA predictors. TWA and HCM risk factors did not predict VA. Conclusions In HCM, microvolt QRSA is a novel, rate-dependent phenomenon that can exist without TWA and is associated with greater left ventricular thickness. QRSA increases VA risk 3-fold in all patients, whereas the absence of QRSA confers low VA risk in patients with <2 risk factors. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02560844.

Dataset Information

QRS/T-wave and calcium alternans in a type I diabetic mouse model for spontaneous postmyocardial infarction ventricular tachycardia: A mechanism for the antiarrhythmic effect of statins.

Publications

QRS/T-wave and calcium alternans in a type I diabetic mouse model for spontaneous postmyocardial infarction ventricular tachycardia: A mechanism for the antiarrhythmic effect of statins.

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