13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

RT-107

Evaluation of myocardial lesion after radiofrequency catheter ablation using in-111-antimyosine antibodies: preliminary results

X. Vinolas, I. Carrió*, R. Oter, O. Aslan, M. Ballester, P. Torner, M.C. Varela, A. Bayés de Luna.
Cardiology and Cardiac Surgery Department,
*Nuclear Medicine Department, Hospital de Sant Pau, Barcelona, Spain

Pilot study

Patients

From July 1994 to January 1995, 30 consecutive patients submitted to our institution for a RFCA procedure accepting to have an evaluation of antimyosine antibody uptake after the procedure were included. Five patients were excluded due to underlying heart disease, thus 25 patients remained for study. Clinical profile was: 1) 10 males, 15 females; 2) mean age 41.5; 3) all patients presenting intranodal tachycardia and tachycardia due to a kent patways where free of drugs (at least 5 half-lives) before the procedure. No patients were taking cardiotoxic drugs. Thirteen accessory pathways ablation were performed in 12 patients, 11 slow pathway ablation, 1 atrial flutter ablation and 1 AV node ablation.

RFCA procedure

RFCA was made using standard methods for diagnosis described previously. For intranodal tachycardia, slow pathway ablation using an anatomical-electrophysiological approach was used. Accesory Kent RFCA was performed at the atrial insertion in right pathways and in ventricular (or atrial in some cases) insertion in left sided patways using a retrograde aortic approach. Complete AV ablation was performed at a position with the most proximal His recording. Atrial flutter ablation was performed using the technique described by Cossio et al¹⁰.

Patients were sedated during the procedure with Midazolam and Fentanest if needed. No cardioversion shocks were needed in any patient. 5000u iv heparine was administered during the procedure.

radiofrequency energy delivery

RF energy delivery was made using automatic close loop temperature (target temperature 60° to 70° C, from 30 to 120 sec, EPT1000® or Medtronic Attakr® generator). Standard 4 mm tip catheters were used.

rfca end-points

The primary end-points were: 1) the absence of conduction through the accessory pathway 30 minutes after the energy application; 2) no induction of tachycardia and absence of dual pathway physiology (or a single echo beat) on isoprenaline. In atrial flutter the interruption and noninducibility of the arrhythmias was the end-point. The procedure was interrupted after 4 to 5 hours if no success was achieved.

treatment after rfca and in hospital stay

No patient received antiarrhythmmic drugs after the ablation procedure. After the procedure patients were taking 125 mg aspirine/day if no contraindication was present.

Post-RFCA evaluation

An echocardiogram was performed 24 to 48 hours after ablation, or immediately if complications occured. A Holter recording was performed 24 hours after the procedure.

Indium-111-monoclonal antimyosin antibody uptake was evaluated using previously described method 7 to 10 days after the procedure. Heart-lung ratio was evaluated. The presence of diffuse or localize antibody uptake was also evaluated. Using our laboratory normal values we considered a heart-lung ratio (HLR) >1.55 as pathological. A HLR ratio between 1.55 and 1.7 was considered moderately positive and > 1.7 very positive.

Main Results

Main heart-lung index for the whole group was 1.61 ± 0.17. Eleven out of 25 patients showed an abnormal antimyosine uptake. The results in each type of ablation are shown in table I, and separated for mild abnormal (1.55-1.7) or clearly abnormal (> 1.7).

TABLE I

The results were compared to a control group (n = 19) of healthy subjects of the same institution and evaluated by the same investigators (already published elsewere¹¹). Mean age of the group was 29 ± 6 y, 10 men. HLR in this group was 1.39 ± 0.08. Using this control group the normal HLR was established (mean + 2SD = 1.55). None of the normal subjects showed a HLR greater than 1.55 compared to 11 of the 25 patients without underlying heart disease after RFCA (p < 0.05).

Conclusions

We found a high incidence of positive in-111-antimyosine uptake in patients after RFCA (44%) even when patients with possible known factors altering antimyosine uptake are excluded (underlying heart disease, alcohol intake, etc.). Although this could indicate that RFCA produces a diffuse myo-cardial damage it can not be ruled out that these patients has already a positive uptake before the procedure. For this reason a prospective study was designed.