Abstract/Text: The goal of therapy for bradycardia or tachycardia is to rapidly identify and treat patients who are hemodynamically unstable or symptomatic due to the arrhythmia. Drugs or, when appropriate, pacing may be used to control unstable or symptomatic bradycardia. Cardioversion or drugs or both may be used to control unstable or symptomatic tachycardia. ACLS providers should closely monitor stable patients pending expert consultation and should be prepared to aggressively treat those with evidence of decompensation.

Abstract/Text: BACKGROUND: Patients who survive life-threatening ventricular arrhythmias are at risk for recurrent arrhythmias. They can be treated with either an implantable cardioverter-defibrillator or antiarrhythmic drugs, but the relative efficacy of these two treatment strategies is unknown.
METHODS: To address this issue, we conducted a randomized comparison of these two treatment strategies in patients who had been resuscitated from near-fatal ventricular fibrillation or who had undergone cardioversion from sustained ventricular tachycardia. Patients with ventricular tachycardia also had either syncope or other serious cardiac symptoms, along with a left ventricular ejection fraction of 0.40 or less. One group of patients was treated with implantation of a cardioverter-defibrillator; the other received class III antiarrhythmic drugs, primarily amiodarone at empirically determined doses. Fifty-six clinical centers screened all patients who presented with ventricular tachycardia or ventricular fibrillation during a period of nearly four years. Of 1016 patients (45 percent of whom had ventricular fibrillation, and 55 percent ventricular tachycardia), 507 were randomly assigned to treatment with implantable cardioverter-defibrillators and 509 to antiarrhythmic-drug therapy. The primary end point was overall mortality.
RESULTS: Follow-up was complete for 1013 patients (99.7 percent). Overall survival was greater with the implantable defibrillator, with unadjusted estimates of 89.3 percent, as compared with 82.3 percent in the antiarrhythmic-drug group at one year, 81.6 percent versus 74.7 percent at two years, and 75.4 percent versus 64.1 percent at three years (P<0.02). The corresponding reductions in mortality (with 95 percent confidence limits) with the implantable defibrillator were 39+/-20 percent, 27+/-21 percent, and 31+/-21 percent
CONCLUSIONS: Among survivors of ventricular fibrillation or sustained ventricular tachycardia causing severe symptoms, the implantable cardioverter-defibrillator is superior to antiarrhythmic drugs for increasing overall survival.

Abstract/Text: BACKGROUND: In the differential diagnosis of a tachycardia with a wide QRS complex (greater than or equal to 0.12 second) diagnostic mistakes are frequent. Therefore, we investigated the reasons for failure of presently available criteria, and we identified new, simpler criteria and incorporated them in a stepwise approach that provides better sensitivity and specificity for making a correct diagnosis.
METHODS AND RESULTS: A prospective analysis revealed that current criteria had a poor specificity for the differential diagnosis. The value of four new criteria incorporated in a stepwise approach was prospectively analyzed in a total of 554 tachycardias with a widened QRS complex (384 ventricular and 170 supraventricular). The sensitivity of the four consecutive steps was 0.987, and the specificity was 0.965.
CONCLUSIONS: Current criteria for the differential diagnosis between supraventricular tachycardia with aberrant conduction and ventricular tachycardia are frequently absent or suggest the wrong diagnosis. The absence of an RS complex in all precordial leads is easily recognizable and highly specific for the diagnosis of ventricular tachycardia. When an RS complex is present in one or more precordial leads, an RS interval of more than 100 msec is highly specific for ventricular tachycardia. This new stepwise approach may prevent diagnostic mistakes.