Tachycardia: defibrillators implanted with endocardial leads decreased mortality.

Clinical bottom line (level 2b)

Patients with ventricular tachyarrhythmias who had a cardioverter-defibrillator implanted with an endocardial lead system, were less likely to die than those with an epicardial lead system (NNT = 13 at unknown) .
Patients given a cardioverter-defibrillator implanted with an endocardial lead system, were less likely to have a successful implantation (NNH = 9 at minutes) .

The PCD Investigator Group : Journal of the American College of Cardiology 1994; 23: 1521-1530

Expires October 2004

The study

Unblinded unconcealed un-randomised trial without intention-to-treat
Setting: 125 institutions, USA

1221 patients (aged mean 59 years, 83% male) documented cardiac arrest or ventricular fibrillation unrelated to transient or reversible clinical events with clinical and electrophysiological evaluation that suggested that the patient was at risk for recurrent cardiac arrest and sustained, drug-refractory ventricular tachycardia (sustained defined as ventricular tachycardia >30 seconds duration; refractoriness defined as either spontaneous ventricular tachycardia recurrence, induction of sustained ventricular tachycardia at electrophysiologic study or intolerance to the antiarrhythmic agent.)

Excluded if

refractory supraventricular arrhythmias with rapid ventricular rates despite antiarrhythmic drug therapy

ventricular tachycardia or ventricular fibrillation due to proarrhythmic effects of antiarrhythmic drugs

ventricular tachycardia or ventricular fibrillation due to metabolic or electrolyte abnormalities, recent myocardial infarction or myocardial ischaemia

frequent, nonsustained ventricular tachycardia or incessant, sustained ventricular tachycardia

projected life-expectancy <6 months at the time of consideration of device therapy

unwillingness to comply with device follow-up procedures for medical or administrative causes

Note:

Selection of type of system was at the investigators discretion

Control Group: (n = 616, 616 analysed): implantable cardioverter-defibrillator implantation of an epicardial thoracotomy lead system
Experimental Group: (n = 686, 686 analysed): implantable cardioverter-defibrillator implantation of an endocardial nonthoracotomy lead system
Implantable device system included a pulse generator (Medtronic models 7216A and 7217B). The cardioverter can be programmed to give shocks between 0.2 and 34 J.
100% followed for 7 months mean, range 0 to 33 months, but longer in epicardial (mean 9.5) than endocardial (mean 5.9) placements

The evidence

Epicardial (control) vs endocardial (experimental) placement

Outcome	Time to outcome	CER	EER	RRR (95% CI)	ARR (95% CI)	NNT (95% CI)
death	7 months	68 (11.0%)	19 (3.14%)	72.0% (53.0% to 83.0%)	7.90% (5.06% to 10.7%)	13 (9 to 20)
successful implantation	minutes	614 (99.7%)	605 (86.6%)	12% (9% to 14%)	11.5% (9.0% to 13.9%)	-9 (-7 to -11)

Similar numbers of successful shocks were delivered by both systems (88.5% success epicardial vs 91.7% endocardial, p>0.2)

More females and patients with the indication for implantation of 'sudden cardiac death' were in the endocardial group.

Comments

The use of a cohort design and unbalanced follow-up in the two groups means the estimate of mortality data may be exaggerated.

Citation

The PCD Investigator Group , : Clinical outcome of patients with malignant ventricular tachyarrhythmias and a multiprogrammable implantable cardioverter-defibrillator implanted with or without thoracotomy: An international multicenter study. Journal of the American College of Cardiology 1994; 23: 1521-1530

Contributor: Clare Wotton and Bob Phillips, October 1999
Reviewer:

_{Clinical Question.}

_Patient	_{ventricular tachyarrhythmia}
_{Intervention or Exposure}	_{implantable defibrillator implanted with thoracotomy}
_Comparison	_{implantable defibrillator implanted without thoracotomy}
_Outcome	_{successful implantation and death}