MMP9 and Ventricular arrhythmia: Clinical studies have suggested that myocardial MMP-9 is increased in patients with cardiac dysfunction13, 14, 15, and high serum levels of MMP-9 are associated with increased ventricular arrhythmia and sudden cardiac death16, 17, 18; however, whether the relationship between MMP-9 and ventricular arrhythmia is causal or an epiphenomenon is not clear.