The Effect of Intravenous Amiodarone on Heart Rate in Patients with Acute Myocardial Infarction or Ischemia and Sinus Tachycardia: Material and Methods

Intravenous Amiodarone Administration Protocol
Amiodarone was administered IV in a dose of 300 mg dissolved in 50 to 100 ml of glucose solution over a 15-minute period. Sinus rates (recorded by cardiac monitoring) were registered before and 15 minutes after the end of infusion. Cuff blood pressure was measured every 5 minutes until 15 minutes after drug administration.
Each patient served as his own control. Excluding three patients, all were observed for at least 30 minutes before amiodarone was given to rule out spontaneous variations in sinus rates. At the end of the 30-minute observation period, sinus rates had to persist in the ±5 beats/min range of the originally recorded heart rate. In addition, care was taken not to administer any drug that could alter the baseline sinus tachycardia; eg, (3-blockers, sedatives, diuretics, analgesics. Three patients received IV amiodarone within ten minutes of arrival to the coronary care unit. This treatment preceded any other kind of management, including administration of analgesics. Two of these patients had severe chronic obstructive pulmonary disease (patients 4 and 15, Table 1), and therefore, (3-blockers were contraindicated.

Patients in heart failure (Killip class 2 to 4) were initially treated with diuretics. Only those patients in whom sinus tachycardia persisted for at least two hours after clinical improvement was observed received amiodarone. Two patients in cardiogenic shock were given amiodarone after all other modalities of medical therapy had failed and an attempt to reduce the sinus heart rate was thought necessary. In these two patients, the ongoing medical therapy was kept constant for the 30-minute observation period before amiodarone administration, and in both cases the sinus rates remained constant.
Mean and standard deviation were calculated for each set of data. A simple linear regression was used to correlate data before and after treatment with amiodarone. Students paired t test was used for heart rate differences due to amiodarone. A value of r >0.5 was considered statistically significant as was p<0.05.

Category: Myocardial Infarction

Tags: heart rate, Ischemia, myocardial infarction, sinus tachycardia