Sabrina L. Wilbur

Ibutilide for pharmacological cardioversion of atrial fibrillation and flutter: impact of race on efficacy and safety.

ObjectiveTo evaluate the racial differences in the efficacy and safety of ibutilide in patients with recent-onset (<2 weeks) atrial fibrillation and atrial flutter. MethodsThis study included 58 consecutive patients with recent-onset atrial fibrillation (n = 34) and atrial flutter (n = 24). The mean age was 65.7 ± 14.6 years (range, 37–86 years), 47% were women (n = 27) and 34% (n = 20) were African Americans. The duration of arrhythmia ranged from 3 hours to 2 weeks. All patients had echocardiography, were on therapeutic anticoagulation, had a fairly well controlled ventricular rate, normal QTc interval on 12-lead electrocardiography, and normal serum electrolytes. Ibutilide was administered as an intravenous infusion with a maximal dose of 2 mg. ResultsThe overall conversion rate to sinus rhythm was 66% (n = 38), with 62% (n = 21) with atrial fibrillation and 71% (n = 17) of atrial flutter. Most conversions (84%) occurred within 45 minutes of ibutilide infusion. The mean time to arrhythmia conversion was 37.4 ± 59.8 minutes. Race had a significant impact on efficacy, with increased conversions seen in African Americans (P = 0.004) and increased nonconversion seen in whites (P = 0.02). Successful conversion was not affected by the left atrial size or the presence of valvular heart disease, hypertension, heart failure, coronary heart disease, and diabetes mellitus. QTc intervals were prolonged after drug administration, with a mean change of 24.6 milliseconds for all patients. The QTc prolongation after drug administration was greater in African Americans than in whites (27.4 vs. 23.3 milliseconds). Torsade de pointes occurred in 4 patients (3 African Americans) and was treated with intravenous magnesium sulfate and electrical cardioversion. ConclusionIbutilide used for pharmacological cardioversion of atrial fibrillation and atrial flutter is more effective in African Americans but carries a higher risk of torsade de pointes.

Use of ibutilide for cardioversion of recent-onset atrial fibrillation and flutter in elderly.

Ibutilide is a class III antiarrhythmic drug used for pharmacological cardioversion of recent-onset atrial fibrillation and flutter. The objective of the study was to assess the efficacy of ibutilide in elderly patients (age, ≥65 years). The study population consisted of 32 consecutive elderly patients (17 women, 15 men; mean age, 76 ± 8 years; age range, 65–94 years) with recent-onset atrial fibrillation (19 patients) or flutter (13 patients). Ibutilide was administered 1-mg intravenously over 10 minutes, and a second 10-minute infusion of 1-mg was given if the arrhythmia did not terminate within 10 minutes after the end of initial infusion. Twenty-six patients received two 1-mg doses of ibutilide. The rate of successful arrhythmia termination was 59% (19 patients): 63% in patients with atrial fibrillation (12 of 19) and 54% in atrial flutter (7 of 12). The mean conversion time was 33 ± 45 minutes. Three-fourths of the conversions occurred within 45 minutes of treatment. No clinical variables were correlated with success of cardioversion. Patients with a left atrial size of 50 mm or larger had a conversion rate of 50% compared with a conversion rate of 61% in patients with a left atrial size of less than 50 mm (P = NS). Ibutilide-induced lengthening in the QTc interval was of 17 ± 21 milliseconds. Cardiac complications were torsade de pointes (1 patient), nonsustained ventricular tachycardia (1 patient), and transient bradycardia (1 patient). Torsade de pointes was terminated with direct current cardioversion. Ibutilide appears to be an effective drug for conversion of recent-onset atrial fibrillation and flutter in elderly patients under monitored conditions. Complications are rare and transient.

QT Interval Prolongation With Global T Wave Inversion: A Novel ECG Finding in Acute Pulmonary Embolis

OBJECTIVE The purpose of this study was to report a novel electrocardiographic (ECG) phenomenon in acute pulmonary embolism characterized by QT interval prolongation with global T-wave inversion. METHODS Among a total of 140 study patients with a confirmed diagnosis of acute pulmonary embolism, patients who fulfilled the inclusion criteria for QT interval prolongation with global T-wave inversion were examined. Each of these patients had undergone a detailed clinical evaluation including testing for myocardial injury and echocardiography. RESULTS QT interval prolongation with global T-wave inversion was found in five patients (age 51-68 years) with acute pulmonary embolism. Four were women. Acute pulmonary embolism was diagnosed by ventilation-perfusion scan in three patients and by spiral computed tomography in other two patients. None of the patients had any right or left ventricular regional wall motion abnormalities on echocardiography. All patients had changes characteristic of hemodynamically significant pulmonary embolism, including right ventricular stunning or hypokinesis and dilatation in five patients with paradoxical septal motion in four. Acute coronary syndrome was ruled out in each patient by clinical evaluation, serial ECGs and cardiac markers, and lack of regional wall motion abnormalities on echocardiography. Prolongation of QT intervals (QTc 456-521 ms) with global T-wave inversion was noted on presentation. The ECG changes gradually resolved in 1 week in all patients with appropriate treatment of acute pulmonary embolism. One patient died. None of the patients developed torsade de pointes. CONCLUSIONS Acute pulmonary embolism may occasionally result in reversible QT interval prolongation with deep T-wave inversion, and, thus should be considered among the acquired causes of the long QT syndrome.