Acute Effect of Intravenous Propafenone for Atrial Fibrillation Refractory to Transthoracic Electrical Cardioversion

BACKGROUND AND OBJECTIVES: Various intravenous (IV) antiarrhythmic drugs in patients with atrial fibrillation (AF) refractory to electrical cardiooversion have been attempted. We assessed the efficacy of IV propafenone in patients with AF who failed to achieve normal sinus rhythm using standard external direct current (DC) cardioversion. SUBJECTS AND METHODS: Of the 77 AF patients who underwent a DC cardioversion, 18, who were refractory for up to a maximal 360 joules of external DC cardioversion, were included in this study. Propafenone was infused for 10 minutes at doses of 2 mg/kg (n=3), 2.5 mg/kg (n=8), and 3 mg/kg (n=7) followed by repeated DC cardioversion. RESULTS: The mean age of the patients receiving propafenone was 55+/-14 years and 21% were women. The mean ejection fraction and the average diameter of the left atrium were 56+/-5% and 42+/-7 mm, respectively. The AF cycle length increased following propafenone infusion form 160+/-23 ms to 278+/-62 ms (p<0.05). The AF converted to a normal sinus rhythm following propafenone infusion in three patients. Thirteen patients were successfully cardioverted following IV propafenone infusion, with a mean accumulated energy of 410+/-216 joules (689+/-373 joules prior to propafenone infusion, p<0.05). Cardioversion failed in 2 patients;therefore, the success rate of the cardioversion in patients who received IV propafenone was 88.9% (16/18). No significant adverse effects were observed. CONCLUSION: IV propafenone can be safely used to enhance the efficacy of cardioversion in patients with AF refractory to transthoracic DC cardioversion.

Factors Affecting Coronary Flow Reserve: Measured by Transthoracic Doppler Echocardiography

BACKGROUND AND OBJECTIVES: Coronary flow reserve (CFR) is considered an important index of the functional significance of coronary artery stenosis, but is influenced by several factors, such as left ventricle hypertrophy (LVH), diabetes mellitus (DM), hyperlipidemia and smoking. Measurement of the coronary flow velocity of the left anterior descending coronary artery (LAD) by transthoracic Doppler echocardiography (TTDE) is feasible, and provides reliable information. The purpose of this study was to investigate the relationship between CFR and LVH, DM, hyperlipidemia and hypertension in patients with or without coronary artery disease, and to assess the prominent factors influencing CFR. SUBJECTS AND METHODS: Coronary angiographies were performed in 38 patients to evaluate chest pain. The distal LAD flow velocity was measured by TTDE, and the CFR calculated as a ratio of the hyperemic and baseline mean diastolic velocities. The CFR was compared with clinical, echocardiographic and angiographic parameters. RESULTS: The CFR was similar in patients both with and without hypertension, DM, high LDL-cholesterol levels and low ejection fraction(<40%). The mean CFR was lower in patients with (50% LAD stenosis than in patients with no significant stenosis. The CFR of patients with a left ventricle wall thickness of (12mm was lower than in those without LVH. The multivariate analysis of the aforementioned factors showed that LVH was the factor most influencing to the CFR (p<0.05). CONCLUSION: When using CFR as a functional parameter of LAD stenosis, one should consider LVH as one of the factors attributed to CFR modification.