I Clinical and Community Studies

Canadian hospital's experience with the automatic implantable cardioverter/defibrillator A

Arjun D. Sharma, MD, FRCPC Gerard Guiraudon, MD, FRCPC George J. Klein, MD, FRCPC Raymond Yee, MD, FRCPC

The automatic implantable cardioverter/defibrillator is a device that can be implanted in patients for treatment of recurrent ventricular tachycardia and ventricular fibrillation. It was recently approved for clinical use in Canada. The authors describe their experience with 12 patients (mean age 51.3 years) who underwent implantation of a defibrillator. All 12 patients had a history of documented ventricular fibrillation, which was idiopathic in 3 and due to ischemic heart disease in 9. Electrophysiologic testing revealed inducible ventricular tachycardia or ventricular fibrillation in 8 of the 10 patients tested. An important criterion for selection for implantation was failure of pharmacologic therapy to suppress ventricular arrhythmias induced during electrophysiologic testing. Of the 12 patients, 1 died within 24 hours after implantation. During a mean follow-up period of 15.5 months there were no further deaths. All the surviving patients expressed satisfaction with the device; five of the seven under the age of 60 years have returned to work, and one has returned to school. This initial favourable experience with the automatic implantable cardioverter/defibrillator suggests that future increases in the availability of the device and improvements in its function will lead to much more widespread use, as the population of patients at risk of sudden cardiac death is large. From the departments of Medicine and Surgery, University Hospital, Robarts Research Institute and University of Western Ontario, London

Reprint requests to: Dr. Arjun D. Sharma, Department of Medicine, University Hospital, PO Box 5339, Stn. A, London, Ont. N6A 5A5

L'implantation intra-corporelle d'un appareil de cardioversion-defibrillation automatique peut etre indiquee dans les cas de tachycardie et de fibrillation ventriculaires recidivantes. Son emploi est maintenant permis au Canada. Nous en avons fait l'essai chez 12 malades (Age moyen 51,3 ans) qui ont tous des antecddents confirmes de fibrillation ventriculaire. Celle-ci est idiopathique chez trois malades et causee chez les autres par une cardiopathie ischemique. L'etude electrophysiologique de 10 malades provoque chez 8 d'entre eux une tachycardie ou une fibrillation ventriculaire. La resistance de ces arythmies a la pharmacotherapie nous a servi d'important critere ddcisionnel pour l'implantation. Un opdre meurt dans les 24 heures; nul d'ces parmi les autres pendant un suivi moyen de 15,5 mois. Tous les survivants sont satisfaits de l'appareil; des sept d'entre eux qui n'Qnt pas encore 60 ans, cinq ont repris le travail, et un est retourne a l'ecole. Ces premiers resultats favorables nous incitent k prddire qu"a la faveur de sa disponibilitd et des ameliorations qu'on y apportera, cet appareil intra-corporel sera de plus en plus employd, vu le grand nombre de malades qui sont sujets a la mort subite d'origine cardiaque. C

ertain subsets of patients with cardiac disease are at high risk of sudden cardiac _R%o death despite prophylactic treatment with antiarrhythmic drugs or surgical techniques. These patients include those resuscitated from an out-ofhospital cardiac arrest' and those who survive myocardial infarction with left ventricular dysfunction2 or complex ventricular arrhythmias3'4 or both. However, the introduction into clinical practice of CMAJ, VOL. 137, NOVEMBER 1, 1987

809

the automatic implantable cardioverter/defibrillator represents a major improvement in the therapy of these patients.5-9 Although this device was only recently approved for general use in Canada, a small number of defibrillators have been implanted on an investigational basis over the past 2 years at several medical centres. To help formulate guidelines for the use of such devices in Canada, we present our initial experience with 12 patients who underwent implantation of an automatic implantable cardioverter/defibrillator.

* Absence of supraventricular arrhythnuas with rapid ventricular rates. * Relatively infrequent occurrence of the malignant ventricular arrhythmia (less than once per month). * Absence of noncardiac disease that might limit longevity. * Informed consent from the patient for implantation and subsequent follow-up. Twelve patients (11 men and 1 woman with a mean age of 51.3 years) underwent implantation of a defibrillator (AID-B or AID-BR [Cardiac Pacemakers Inc., Minneapolis, Minnesota]) between May 1985 and November 1986. The clinical characteristics of the patients are shown in Table I. Nine of the patients had ischemic heart disease and had a history and electrocardiogram (ECG) consistent with prior myocardial infarction. Three patients had no apparent cardiac disease, as determinecl by the history, ECG, chest roentgenography, two-dimensional echocardiography, ventriculography and coronary angiography. Four patients had two out-of-hospital cardiac arrests; the remaining eight had one. In three patients the initiation of ventricular fibrillation was directly related to exercise; in the remaining nine no apparent precipitating factor could be identified. In one patient the onset of arrhythmias occurred during sleep.

Methods Patient population

The following criteria were used to select patients for implantation of an automatic implantable cardioverter/defibrillator. * Out-of-hospital cardiac arrest with documented ventricular fibrillation requiring defibrillation. * No correctable cause of the cardiac arrhythmia. * Failure of pharmacologic or surgical therapy to suppress ventricular arrhythmias induced by programmed extrastimulus techniques or occurring

spontaneously.

Table I Characteristics of 12 patients with ventricular arrhythmias who were selected for implantatior, automatic defibrillator

ii) :;. t>;:'

lMf

*.'4 .r 3

' ~ r,^~

."! r.

r

trlurrIirr

.

EiV

vd .

I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ d 1.

',

I.

tef n

l

:

BCr CAl;

t

:

"

!.,;Rniv

. . |

proprr

;

_;

F., t

A. r %.; e.

ir

!.

!r

nxtOrov:

Stei rio>toa (}1,,

iCS

", x e

SL

C.(-B AB{

r.

11

t-'.

cItl

a

I'o

C MID *|4' A D BkiL

i92

:r

rr irr ,frtrIr zi rr s ir :enqvti :-t tfrwlt.1',t)].]:

(I

';O. OIf;t O:r:;i:l vr '. !,ar.. 11

;r

':

%

,

iI .,I

:,(

!'