14th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 2000

Jan. 29 - Feb. 5, 2000
Marilleva, Trento, Italy

RT-209

Biventricular pacing: role of ICD

Fiorenzo Gaita, Mario Bocchiardo, Luigi Padeletti*, Cristina Porciani*, Marco Scaglione, Alessandro Costoli*, Laura Vivalda.
Division of Cardiology, Ospedale Civile of Asti, *Division of Cardiology, Ospedale Careggi, Firenze, Italy

Biventricular pacing with a lead implanted via a cardiac vein is a technique recently proposed to correct the electrical and mechanical asynchrony of the left heart in patients with congestive heart failure due to dilated cardiomyopathy with a wide QRS. The preliminary results of the studies published till now^1-3 are encouraging: the functional class significantly decreased, but despite clinical improvement due to biventricular pacing, total mortality was still high in these severely compromised patients. In the French Pilot Study¹ 18 out of 53 patients (33%) died, 6 (11.3%) of them from sudden death, during a mean follow up of 15.7 months. In the InSync Study population³, 17 out of 103 patients (16.5%) died, 11 of than suddenly, during a mean follow up of 156 days. These data confirm that sudden death accounts for 33-65% of the totality^4,5. Even if not all sudden deaths can be due to ventricular tachyarrhythmias, an implantable cardioverter defibrillator could have been lifesaving in more than a half of these patients. For these reasons implantable cardioverter defibrillators with biventricular pacing are now under investigation to resynchronize ventricles and to treat malignant ventricular arrhythmias. The first implantation of a cardioverter defibrillator with biventricular pacing using a catheter in the coronary sinus was done in our centre in the August 1998: at that time a specific device was not available, so for the first patients we had to use an Y connector to join the lead from right and left ventricle. Only since spring of 1999 a device with a supplemental entrance dedicated to the coronary sinus lead has been made available, and since summer another new device with sensing and pacing channels programmability is under investigation.

Between August ’98 and October ’99, we selected patients with congestive heart failure⁶ who met the following criteria: no acute myocardial infarction, no unstable angina, no cardiac revascularization and no surgery in the last 3 months, were functional classes IIB, III or IV despite full drug therapy (including diuretics, digitalis, ace-inhibitors and, when tolerated, beta-blockers), QRS width ³140 ms, left ventricular ejection fraction £35%, sustained ventricular tachycardia or fibrillation refractory to antiarrhythmic drugs including amiodarone. There were 16 male, 3 female, with a mean age of 63±7 years. Dilated cardiomyopathy was ischemic in 8, idiopathic in 9 and valvular in 2; functional class was IV in 3, III in 8 and IIB in 8. Congestive heart failure was present for a mean duration of 24.9 months (±18). The first patient who received atrio-biventricular pacing had a cardioverter defibrillator implanted 4 months before and had upgrading while he was under continuous dopamine and dobutamine infusion and under ultrafiltration. To pace left ventricle a unipolar lead was inserted through the left cephalic or subclavian vein in the coronary sinus and advanced in a lateral or posterolateral or anterior epicardial vein under fluoroscopic guidance.

An echocardiogram was performed before implant and repeated 3-8 days, 1, 3 and 6 months later. The following parameters were recorded: the difference between the interval QRS onset-pulmonary ejection onset and the interval QRS onset-aortic ejection onset, the left atrium antero-posterior diameter, the left ventricle end-diastolic and end-systolic diameter, the left ventricle filling time, the left ventricle ejection fraction, the mitral regurgitation duration and area, and the integral of transaortic flow. A six minute walking test was performed before implant (in the 18 patients who were able to walk) and repeated at 1, 3 and 6 months. The implant was successfully carried on in 19 out 21 patients (91%) in whom it was attempted, with a mean X-ray exposure time of 71±32 minutes. The acute values of the R wave amplitude in the right and left ventricle were respectively 13.6±5.7 mV and 9±4.9 mV, with a delay between the electrograms of 72±32 ms. The width of the spontaneous and the paced QRS was 172±19 ms and 149±19 ms respectively. The pacing thresholds (at 0,5 ms width) were 0.7±0.4 V for right ventricle, 0.9±0.8 V for coronary sinus and 1.2±0.9 V for biventricular pacing. In all patients ventricular fibrillation was induced twice and was always correctly recognised and successfully treated: the amplitude of the electrograms recorded by the sensing leads was 5-20 mV. No problem of over or undersensing was detected at the moment of the implant of the devices with ventricular blanking periods of 135 and 150 ms. The defibrillation threshold was not searched and only 15-21 J were successfully tested in each patient.

Follow-up: during the mean follow up of 191±100 days, 1 patient died from severe pump failure, 3 days after the implant: he was the first patient implanted, who was in transplant active waiting list for more than 6 months. Two patients (10.5%) had coronary sinus lead microdislodgement few days after the implant: one had phrenic stimulation and the other had inappropriate shocks due to double sensing (disappeared after lead repositioning). Eight patients (42%) had intervention of the cardioverter defibrillator with shock: 4 (21%) had only appropriate shocks, 2 (10.5%) only inappropriate shocks and the last 2 (10,5%) had both appropriate and inappropriate shocks. All the inappropriate shocks happened during sinus tachycardia with spontaneous atrioventricular conduction and didn’t recur after adequate reprogramming of upper rate and of atrioventricular delay. The echocardiograms performed during follow up showed a narrowing of the delay between the onset of right and left ventricular outflow from 42±23 ms to 20±17 ms, a reduction of the mitral regurgitation area from 7.2±4.1 cm² to 3.7±0.8 cm² at 1 month, with the disappearance of the telediastolic component. Functional class improved from 2.74±0.73 before, to 1.40±0.52 three months after the implant. This was confirmed by the distance of the six minutes walking test, that increased from 325±137 to 434±38 meters.