Time Dependence of Ventricular Tachyarrhythmias After Myocardial Infarction: A MADIT-CRT Substudy.

OBJECTIVES: The purpose of this study was to assess the relationship between the time since a myocardial infarction (MI) and the risk of ventricular tachyarrhythmic events (VTEs) in patients with left ventricular dysfunction and mild symptoms of heart failure. BACKGROUND: Patients with left ventricular dysfunction after MI are at high risk for VTEs. METHODS: Ventricular tachycardia (VT), ventricular fibrillation (VF), or death as a function of time since MI was assessed in 693 patients enrolled in the MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy). Patients were categorized as those with a period of <3 years since an MI (lowest quartile, n = 172) versus those with a period of ≥3 years since an MI (n = 521). Risk of VT/VF or death was compared. RESULTS: Cumulative probability of VT/VF or death was significantly higher among patients in the highest quartile of time since an MI compared with those in the lowest quartile (41% vs. 22%, p = 0.015). Multivariate analysis showed that in patients with left bundle branch block (LBBB), those with a period of ≥3 years since an MI had a significantly higher risk of VT/VF or death (hazard ratio: 2.33; 95% confidence interval: 1.43 to 3.80; p = 0.001) and a higher risk of VT/VF (hazard ratio: 3.18; 95% confidence interval: 1.71 to 5.90; p < 0.001) compared with patients with a period of <3 years since an MI. These findings were consistent when the time since an MI was analyzed in a continuous fashion. A significant relationship between the time since an MI and outcomes was not observed in patients with non-LBBB. CONCLUSIONS: Among post-MI patients with left ventricular dysfunction and LBBB, the risk of VTEs is directly related to the time since an MI occurred. (Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy [MADIT-CRT]; NCT00180271).

Relationship between elevated serum gamma-glutamyltransferase activity and slow coronary flow.

OBJECTIVES: We evaluated the relationship between coronary blood flow and serum gamma-glutamyltransferase (GGT) activity in patients with slow coronary flow (SCF). STUDY DESIGN: The study included 90 patients (47 men, 43 women; mean age 50.8+/-9.4 years) with SCF and 88 patients (45 men, 43 women; mean age 51.4+/-8.8 years) with coronary artery disease (CAD), whose diagnoses were made by coronary angiography. Patients with CAD had normal coronary flow. Coronary flow was quantified using the corrected TIMI frame count (TFC) method and serum levels of gamma-glutamyltransferase were measured. The results were compared with those of a control group consisting of 86 age- and sex-matched patients who had normal coronary arteries and normal coronary flow. RESULTS: The three groups were similar with respect to body mass index, presence of hypertension and diabetes mellitus, lipid profiles, and fasting glucose. The use of medications was significantly more common in the CAD group (p<0.01). Compared to the control group, serum GGT activity was significantly increased in both SCF and CAD groups (p<0.01), but these two groups did not differ significantly in this respect (p=0.71). The TFCs for all the epicardial coronary arteries and the mean TFC were significantly higher in the SCF group (p<0.01). Patients with CAD and the controls had similar TFC parameters. The mean TFC showed a positive and moderate correlation with serum GGT activity (r=0.326; p<0.001). In regression analysis, serum GGT activity was found as the only independent predictor of the mean TFC (beta=0.309; p<0.001). CONCLUSION: We have shown for the first time an association between increased serum GGT activity and SCF. Further clinical studies are needed to clarify the physiopathologic role of serum GGT activity in SCF.

Serum gamma-glutamyl transferase activity increased in patients with coronary artery ectasia.

BACKGROUND: Serum gamma-glutamyl transferase (GGT) activity, an enzyme responsible for the extracellular catabolism of antioxidant glutathione, may directly take part in atherogenesis and evolve as a potential biochemical risk indicator of cardiovascular morbidity and mortality. An important characteristic of coronary artery ectasia (CAE) is the fact that in 85% of the cases, atherosclerotic coronary disease accompanies it. The relation between CAE and serum GGT activity has not been studied so far. Hence, we decided to investigate the serum GGT level in patients with CAE. METHODS: We measured serum GGT activity in 88 consecutive patients (48 males) with isolated CAE and 86 patients with coronary artery disease (CAD) and 84 controls. CAE was defined as being without any stenotic lesions with a visual assessment of the coronary arteries showing a luminal dilatation 1.5-fold or more of the adjacent normal coronary segments. Four subgroups were created in accordance with the CAE extension in coronary arteries. RESULTS: There were no statistically significant differences in serum GGT activity among CAE and CAD groups. Serum GGT activity was found significantly increased in patients in both CAE and CAD groups, compared with those in control group (P<0.001, P<0.001, respectively). According to the CAE severity, there were no statistically significant differences in CAE among these subgroups. CONCLUSION: We have shown for the first time that patients with CAE have higher serum GGT activity compared with controls with normal coronary angiograms. Hence, serum GGT activity can be used as a follow-up marker in patients with CAE.