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Abstract Background: Current electrocardiography (ECG) criteria are insensitive for the detection of posterior acute myocardial infarction (AMI) and most of these cases remain undiagnosed. The purpose of this study has been evaluated of prevalence and clinical value of ST-segment in posterior electrocardiography leads during acute myocardial infarction. Materials and Methods: In cross- sectional analytic study, posterior ECG leads (V7, V8 and V9) as well as standard 12 leads in 210 consecutive patients with acute myocardial infarction admitted to CCU wards of Shahid Rijaie hospital. Reinforcing, continuous arrhythmia, hypotension, cardiologic shock, marked heart failure and/or acute pulmonary edema were considered. Related parameters to basic characteristics and next process of patients in two groups with/ without ST- segment elevation in posterior ECG lead were compared. Results: There were 153 patients with ST-segment elevation 1 mm in 2 contiguous leads. 12.4% patients had STE1 mm in 2 posterior leads, either as an isolated finding (4.6%) or in association with STE at inferior or lateral sites (7.8%). The standard 12-lead electrocardiogram was normal in two patients and 5 other patients were admitted with the diagnosis of non-Q infarctions. Tall R waves in V1/V2 developed in 5 cases. In-hospital complications were significantly more frequent among patients with STE in posterior leads (47.4% vs. 20.9% respectively, P=0.01). Conclusion: STE in posterior electrocardiography leads is not uncommon during acute myocardial infarction and may portend a worse in-hospital course.

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Background: Since cardiac surgeons have not kept up with advancements in pacing technology, there has been a tendency to limit the implantation of pacemakers by surgeons. This study compares two eras of pacing therapy including pacemaker implantation by cardiac surgeons and pacemaker set-up by a group of cardiologists in Shahid Rajaee Hospital in Tehran. Materials and Methods: In this cross-sectional study, we compared the existing data from all pacemaker implantations in the first half of 1999 (surgical era, era 1) to that of the first half of 2001 (cardiologists era, era 2). Results: During era 1, a total 114 pacemakers (46.5% male, mean age 63.3 ±18.4) and during era 2, 299 pacemakers (63.9% male, mean age 63.9±18.2) had been implanted. Indications for implantation were nearly similar, with AV block as the most common reason in 21.9% and 19.1% of implantations in eras 1 and 2, respectively. Single chamber pacemakers comprised 86% of implantations during era 1 compared to 54% during era 2 (p<0.01). The mean duration of admission was 18 days during era 1 while it was 10 days during era 2. Pacemaker malfunctions were detected following 7.9% of implantations in era 1 compared to 0.3% of cases in era 2 (p<0.01). Re-do procedures were performed after 2.7% of implantations during era 1 in comparison to 0.3% during era 2 (p<0.01). Conclusion: Pacemaker implantation was performed better by a coordinated pacemaker service run by cardiologist trained in pacemaker implantation.

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Background: Nowadays, many patients with cardiovascular diseases require pacemaker implantation that is associated with few complications such as cardiac and valvular insufficiency. This study aims to compare the development of tricuspid and mitral regurgitation in right ventricular outflow tract (RVOT) and right ventricular apex (RVA) pacing.

Materials and Methods: In this single-blind clinical trial, 164 candidates for permanent pacemaker (PPM) implantation due to sick sinus syndrome or atrioventricular block were randomly divided into 2 equal groups to receive either RVOT or RVA pacing. Patients with heart failure or valvular diseases were excluded from the study. Pre and post-procedural echocardiography after 6 months were performed and the results were compared for the development of mitral and tricuspid regurgitation and probable changes in the ejection fraction (EF).

Results: Age, gender, pacing mode, and baseline cardiac rhythm did not significantly differ between RVOT and RVA pacing groups. The incidence of mitral regurgitation was significantly higher in the RVA group (p=0.033), whereas the incidence of tricuspid regurgitation was similar in both groups (p>0.05). There was a trend toward less tricuspid regurgitation in the RVOT group however, it was not statistically significant. Ejection fraction was not significantly different between the study groups.

Conclusion: It seems that the incidence of mitral regurgitation in RVA pacing is significantly higher than RVOT although this needs further investigation in future studies.