Reduced Arrhythmogenic Potential of Ventricular Paired Pacing During Myocardial Infarction

Since the 1960's, the clinical use of ventricular paired pacing (VPP), a form of continuous postextrasystolic potentiation, to augment cardiac function in cardiogenic shock has been prevented by the stigma of ventricular arrhythmogenesis. Historically, this perception was based on very limited human data on the sickest of the sick when many current medical treatments were long into the future. One such treatment is the use of β‐adrenergic receptor blockade, well accepted now, but antithetical then. A meta‐analysis of canine studies of myocardial infarction was performed to understand the effect β‐blockade had on the incidence of ventricular fibrillation during the VPP treatment (References: Singer, D. H. et al. Bull. N. Y. Acad. Med. 41: 652–669, 1965; Rothfeld, E. L. et al. Am. J. Cardiol. 23: 224–228, 1969; Karayannacos, P. E. et al. Ann. Thorac. Surg. 27:34–41, 1979). Infarctions in 48 animals were produced through ligation of the entire or one to three branches of the left anterior descending coronary artery or the entire left circumflex coronary artery with (n=24) or without i.v. pronetholol or propranolol (n=24). Following ligation, in all studies, VPP had a marked inotropic effect. Without β‐blockade, 16 went into ventricular fibrillation during VPP, while only 5 with β‐blockade did. Statistics Comparison of Proportions Difference=45.83%, 95% Confidence Interval=15.21–68.22, χ 2 = 10.03, P<0.002, Contingency Coefficient=0.42; Odds Ratio=7.60, 95% Confidence Interval=2.07–27.90, z Statistic=3.06, P<0.005; Relative Risk=3.20, 95% Confidence Interval=1.40–7.34, z Statistic=2.75, P<0.01; Number Needed to Treat=2.18, 95% Confidence Interval=4.78–1.41. In conclusion, while not eliminating the potential for induced ventricular fibrillation, the anti‐arrhythmic effect of β‐adrenergic receptor blockage did significantly reduce the incidence from 67% to 21%, a 69% decrease. A clinical trial is necessary to confirm these findings under today's medical landscape, when many heart attack victims are already taking β‐blocking drugs and standard cardiogenic shock therapy includes the powerful anti‐arrhythmic drug amiodarone. Until then, ventricular paired pacing should not be categorized as overtly arrhythmogenic in cardiogenic shock. It does, however, contain a minor potential that must be carefully watched for with ubiquitous defibrillators. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .