[Antitachycardia pacing in patients with left ventricular dysfunction and hemodynamically unstable arrhythmias]

The use of antitachycardia pacing (ATP) has shown itself to be an effective therapeutic option in the treatment of ventricular tachycardia (VT) in carriers of implantable cardioverter defibrillators (ICD).

To assess the safety and efficacy of ATP in ICD carriers with ischemic cardiopathy and systolic dysfunction of the left ventricle (LV) presenting VT badly tolerated hemodynamically.

We studied five patients (four male and one female), survivors of acute myocardial infarction, mean age 56.4 +/- 15.7 years and an ejection fraction < 35%, submitted to ICD implantation by VT inducible in the electrophysiological study (EPS) and refractory to pharmacologic therapy. In three cases the arrhythmia was syncopal and in two the patients felt palpitations and dizziness (systolic blood pressure < 90 mmHg during VT). The ICDs were implanted between March 1996 and October 1997 by transvenous approach in pectoral position. ATP was used as an initial therapeutic alternative (VT zone with a detection frequency of 160-220/min) according to an empirical programme (n = 3) or, whenever feasible, in accordance with the type of VT interruption during EPS (n = 2). During the follow-up of 11 +/- 6 months (2-18), a periodic assessment of the symptomatology and a detailed analysis of episodes of ventricular arrhythmia detected by ICD were made.

Two hundred and fourteen episodes of VT were recorded with a post detection duration of > 2.5 sec treated by ICD. The ATP rate of efficacy was 93%. In 3% of the episodes the ATP did not alter VT; in 2% the rate of VT increased (reduction of the VT cycle > 20%) and in 2% therapeutic exhaustion was observed (after the application of ATP and the maximum number of shocks per episode). In 14 episodes with ATP inefficiency, two syncopes occurred (1% of the total number of episodes treated).

In this study antitachycardia pacing has proven to be a therapeutic option with high rates of efficacy and safety despite its use in survivors of myocardial infarction with moderate to severe compromise of systolic function of the left ventricle and ventricular arrhythmias with hemodynamic instability.