Assessment of the clinical setting, including categorization of arrhythmia as acute or chronic, and as transient, persistent, or recurrent. Anatomic and physiological substrate also should be evaluated.
Defining the goal or endpoint of therapy, which depends on the evaluations in 1 and 2.
Appropriate diagnostic tools in addition to history, physical examination and routine laboratory tests and electrocardiogram include (1) special leads to identify the P waves (esophageal lead, intraatrial electrode, or Lewis leads), (2) Holter monitoring; (3) echocardiography; (4) exercise testing; (5) tilt table test; (6) signal-averaged electrocardiography, and (7) electrophysiologic studies.
Discuss the categories of patients who do not require antiarrhythmic therapy.
Because of the risk of proarrhythmia or exacerbation of preexisting arrhythmia by antiarrhythmia drugs, the trend in the 1970s to suppress ventricular ectopy has diminished. Although controversy still surrounds arrhythmic therapy, in specific circumstances, by general agreement, antiarrhythmia therapy is not indicated:
Asymptomatic atrial ectopy and unsustained supraventricular tachycardia (SVT)
Asymptomatic ventricular ectopy without runs of ventricular tachycardia (VT)
Simple ventricular ectopy in acute myocardial infarction, not associated with hemodynamic compromise
Asymptomatic, unsustained VT with no structural heart disease or other risk indicators
Asymptomatic Wolff-Parkinson-White (WPW) syndrome without known superventricu-lar tachycardia
Mildly symptomatic, simple atrial or ventricular ectopy
When should programmed electrical stimulation (PES) be used in the management of a suspected arrhythmia?
PES studies use percutaneous catheter electrodes placed in the atria and ventricle (usually right venous) to record intracardiac electrograms and to evaluate SVT and ventricular arrhythmias, including VT and ventricular fibrillation (VF). The primary indications for PES are (1) to identify the tachycardia and its mechanisms; (2) to select appropriate therapy; and (3) to map the substrate of the arrhythmia for ablation or (rarely) surgical intervention. The rate of complications is small: death, 0.06%; perforation, 0.2%; major hemorrhage, 0.05%; atrial injury, 0.1%; and major venous thrombosis, 0.2%. PES is especially accurate in evaluation of SVT with induction in 90-95% of patients with clinical atroventricular nodal reentrant tachycardia or WPW. Ablation is used after the mechanism is defined, with deliverance of radiofrequency current through the catheter positioned at the site of the pathway.
PES is extensively used in VT evaluation; sustained VT/VF is reproducible in 75% of survivors of sudden cardiac death and 95% of patients with sustained monomorphic VT. The efficacy of antiarrhythmic therapy also can be evaluated with PES; a 10% recurrence rate is expected over 2 years compared with 50% recurrence with no therapy identified.