Cardiac resynchronization therapy evaluated by myocardial scintigraphy with 99mTc-MIBI: changes in left ventricular uptake, dyssynchrony, and function.

PURPOSE: (99m)Tc-MIBI gated myocardial scintigraphy (GMS) evaluates myocyte integrity and perfusion, left ventricular (LV) dyssynchrony and function. Cardiac resynchronization therapy (CRT) may improve the clinical symptoms of heart failure (HF), but its benefits for LV function are less pronounced. We assessed whether changes in myocardial (99m)Tc-MIBI uptake after CRT are related to improvement in clinical symptoms, LV synchrony and performance, and whether GMS adds information for patient selection for CRT. METHODS: A group of 30 patients with severe HF were prospectively studied before and 3 months after CRT. Variables analysed were HF functional class, QRS duration, LV ejection fraction (LVEF) by echocardiography, myocardial (99m)Tc-MIBI uptake, LV end-diastolic volume (EDV) and end-systolic volume (ESV), phase analysis LV dyssynchrony indices, and regional motion by GMS. After CRT, patients were divided into two groups according to improvement in LVEF: group 1 (12 patients) with increase in LVEF of 5 or more points, and group 2 (18 patients) without a significant increase. RESULTS: After CRT, both groups showed a significant improvement in HF functional class, reduced QRS width and increased septal wall (99m)Tc-MIBI uptake. Only group 1 showed favourable changes in EDV, ESV, LV dyssynchrony indices, and regional motion. Before CRT, EDV, and ESV were lower in group 1 than in group 2. Anterior and inferior wall (99m)Tc-MIBI uptakes were higher in group 1 than in group 2 (p<0.05). EDV was the only independent predictor of an increase in LVEF (p=0.01). The optimal EDV cut-off point was 315 ml (sensitivity 89%, specificity 94%). CONCLUSION: The evaluation of EDV by GMS added information on patient selection for CRT. After CRT, LVEF increase occurred in hearts less dilated and with more normal (99m)Tc-MIBI uptake.

High prevalence of Chlamydia pneumoniae seropositivity in Mexican patients with ischemic heart disease.

BACKGROUND: Risk factors for development of atherosclerosis, such as hyperlipidemia, high blood pressure, smoking habit, and diabetes mellitus, have been identified. The possibility that infectious agents may unchain biological and biochemical reactions related to inflammation, atherogenesis, and vascular thromboses events have recently been described. Chlamydia pneumoniae has been associated with coronary artery disease in some seroepidemiology studies. Reports of this association are limited in the Latin American population; therefore, we conducted a case-control study to explore this issue in the Mexican population. METHODS: Eighty nine patients with scintigraphic evidence of coronary artery disease compared with a control group of 105 individuals were analyzed. Serum levels of IgA, IgM, and IgG against Chlamydia pneumoniae were determined using enzyme immunoassay method in all subjects. Conventional risk factors were also analyzed. RESULTS: High seroprevalence of IgA and IgG with no significant difference between the two groups was found. Prevalence of antibodies was as follows: IgA 56.2% (50/89 patients); IgG 66.3% (59/ 89 patients) in coronary artery disease group; IgA 56.2% (59/105 patients), and IgG 70.5% (74/105 patients) in control group. Among common risk factors for coronary artery disease, significant differences were found in males, in patients with diabetes, and in habitual smokers. CONCLUSIONS: These results suggest a high prevalence of C. pneumoniae infection in the studied population. However, in this series seroprevalence was not evidently associated with coronary artery disease (CAD). To clarify the possible relation between C. pneumoniae and coronary atherosclerosis, additional studies must be performed.