Electrocardiographic diagnosis of acute myocardial infarction in the presence of ventricular paced rhythm.

ST-segment deviation was recently described as the only ECG finding that was useful in the diagnosis of acute myocardial infarction during right ventricular pacing. This report shows that the same sign may also indicate the amount of myocardium in jeopardy and the coronary artery responsible.

Relation of autonomic modulation to recurrence of atrial fibrillation following cardioversion.

The aim of this study was to investigate the time course of changes in autonomic nervous system activity in patients with long-standing atrial fibrillation (AF) following internal electrical conversion to sinus rhythm and to look for differences between patients who do and do not relapse. Time-domain indexes of heart rate variability were calculated from 24-hour Holter recordings on the day of conversion and 1 day and 1 month afterward for 22 patients with chronic (> 3 months) AF. Ten healthy subjects served as a control group. During the day of cardioversion the mean RR interval and its circadian variation differed significantly between controls and patients. The mean values of successive RR intervals that deviated by > 50% from the prior RR interval and the root-mean-square of successive RR interval differences--indexes of vagal modulation--were initially significantly higher in patients than in controls but showed a decrease (p < 0.05) by the second day (from 12.4 +/- 7% to 8.1 +/- 5% to 7.3 +/- 5% and from 49 +/- 9 to 39 +/- 12 to 41 +/- 11 ms, respectively) to levels similar to those of the controls (7.6 +/- 5% and 40 +/- 17 ms, respectively). Only these 2 indexes contained significant prognostic information about relapse: patients who later relapsed had higher initial values than those who did not, and these values remained high during the 2 days after conversion. In conclusion, this study provides data confirming that spontaneous chronic AF in humans results in a significant increase in vagal tone that is reversed with time after restoration of sinus rhythm. Persistently higher values of vagal tone are observed in patients who relapse, and are probably a predictor for recurrence.

Changes in atrial electrical properties following cardioversion of chronic atrial fibrillation: relation with recurrence.

OBJECTIVE: To study the reversibility of atrial electrical remodeling and its relation with recurrence in post-conversion chronic atrial fibrillation (CAF) patients. METHODS: In 28 drug-free CAF patients (mean AF duration 41+/-39 months) electrically converted to sinus rhythm effective refractory period (ERP) at 500 ms, monophasic action potential at 90% of repolarization (MAPd90) at five cycle lengths (CL, 350, 400, 450, 500, 600 ms), and P wave duration were measured three times: within the interval 5-20 min post-conversion, 24 h and 1 month later. Fifteen subjects with no history of AF and normal atrial structure served as a control group. Patients were followed up for recurrence for 1 month; 12 relapsed. RESULTS: ERP changed from 205+/-20 to 243+/-31 to 241+/-24 ms (P<0. 001), attaining a level comparable to that of the controls (238+/-21 ms) within 24 h. MAPd90 significantly (P<0.001) increased (from 175+/-11 to 190+/-19 to 191+/-10 ms at CL 350 ms and 201+/-12 to 234+/-20 and 233+/-23 ms at CL 600 ms) also reaching control levels within 24 h. MAPd90 exhibited an abnormal adaptation to rate only in the first evaluation. P wave duration was prolonged (137+/-33 ms) and exhibited a slower course of shortening (130+/-32 to 123+/-27 ms, P<0.001), reaching control levels within 1 month. Patients with higher values of MAPd90 at CL 350 in the immediate post-conversion period were more likely to relapse (P<0.005). CONCLUSIONS: ERP and repolarization shortening as a result of CAF are reversed within 24 h after conversion, while P wave duration reduces more slowly. Post-conversion MAPd90 values contain prognostic information for recurrence.

Low dose amiodarone and sotalol in the treatment of recurrent, symptomatic atrial fibrillation: a comparative, placebo controlled study.

OBJECTIVE: To assess and compare the safety and efficacy of amiodarone and sotalol in the treatment of patients with recurrent symptomatic atrial fibrillation. DESIGN: Prospective, randomised, single blind, placebo controlled study. SETTING: Tertiary cardiac referral centre. PATIENTS: 186 consecutive patients (97 men, 89 women; mean (SD) age, 63 (10) years) with recurrent, symptomatic atrial fibrillation. INTERVENTIONS: 65 patients were randomised to amiodarone, 61 to sotalol, and 60 to placebo. Patients receiving amiodarone were maintained at a dose of 200 mg/day after a 30 day loading phase. The sotalol dose was 160-480 mg daily, as tolerated. MAIN OUTCOME MEASURES: Recurrence of atrial fibrillation or side effects. RESULTS: In the amiodarone group, 31 of the 65 patients developed atrial fibrillation after an average of six months, while 15 (11 in sinus rhythm and four in atrial fibrillation) experienced significant side effects after an average of 16 months. In the sotalol group, relapse to atrial fibrillation occurred in 47 of the 61 patients after an average of eight months; three experienced side effects during the titration phase. In the placebo group, 53 of the 60 patients developed atrial fibrillation after an average of four months (p < 0.001 for amiodarone and sotalol v placebo; p < 0.001 for amiodarone v sotalol). CONCLUSIONS: Both amiodarone and sotalol can be used for the maintenance of normal sinus rhythm in patients with symptomatic atrial fibrillation. Amiodarone is more effective but causes more side effects.

Amiodarone, sotalol, or propafenone in atrial fibrillation: which is preferred to maintain normal sinus rhythm?

UNLABELLED: This randomized study compared the efficacy and safety of amiodarone, propafenone and sotalol in the prevention of atrial fibrillation. METHODS: The population consisted of 214 consecutive patients (mean age 64 +/- 8 years, 106 men) with recurrent symptomatic atrial fibrillation. After restoration of sinus rhythm, patients were randomized to amiodarone (200 mg/day), propafenone (450 mg/day) or sotalol (320 +/- 20 mg/day). Follow-up evaluations were conducted at 1, 2, 4 and 6 months, and at 3-month intervals thereafter. The proportion of patients developing recurrent atrial fibrillation and/or experiencing unacceptable adverse effects was measured in the three groups by the Kaplan-Meier method. RESULTS: Recurrent atrial fibrillation occurred in 25 of the 75 patients treated with amiodarone compared to 51 of the 75 patients treated with sotalol and 24 of the 64 patients treated with propafenone. Fourteen patients treated with amiodarone, five with sotalol, and one with propafenone experienced adverse effects while in sinus rhythm, necessitating discontinuation of treatment (P < 0.001 for amiodarone and propafenone vs sotalol). The difference between amiodarone and propafenone was statistically nonsignificant when all events were included in the analysis. However, if the analysis was limited to recurrent atrial fibrillation events, amiodarone was more effective than propafenone (P < 0.05). CONCLUSIONS: Amiodarone and propafenone were superior to sotalol in maintaining long-term normal sinus rhythm in patients with atrial fibrillation. Amiodarone tended to be superior to propafenone, though its long-term efficacy was limited by adverse side effects.

Efficacy of amiodarone for the termination of persistent atrial fibrillation.

The efficacy and safety of amiodarone in the conversion of persistent atrial fibrillation (AF) were investigated in a prospective, randomized, controlled study. Of 67 consecutive patients (32 men, mean age 64+/-9 years) with AF lasting >48 hours, 33 received amiodarone and 34 received placebo. Baseline clinical characteristics were similar in the 2 groups. Patients randomized to amiodarone received 300 mg intravenously for 1 hour and then 20 mg/kg for 24 hours. They were also given 600 mg/day orally, divided into 3 doses, for 1 week and thereafter 400 mg/day for 3 weeks. Patients randomized to placebo received an identical amount of saline IV over 24 hours and then oral placebo for 1 month. Conversion to sinus rhythm was achieved in 16 of the 33 patients (48.5%) who received amiodarone and in none of the 34 patients in the placebo group (p <0.001). None of the patients converted to sinus rhythm within the first 3 days. Those who converted had smaller atria than those who did not (diameter 41.9+/-7.2 vs 50.4+/-5.7 mm, p <0.001). Sex, age, baseline heart rate, left ventricular ejection fraction, and the duration of AF did not differ significantly between patients who converted and those who did not. No side effects requiring discontinuation of treatment were observed in either group. Amiodarone, administered both intravenously and orally, appears to be safe and effective in the termination of persistent AF. Left atrial diameter is the sole independent predictor of conversion.