Role of mapping-guided surgery in patients with recurrent ventricular tachycardia

[History of surgical treatment of cardiac arrhythmias in Germany : Surgical treatment of ventricular tachycardia and supraventricular tachycardia, especially pre-excitation syndromes (WPW)]

The history of surgical treatment of ventricular tachycardias (VT) is short, lasting from 1978 until 1993. "Indirect procedures" with infarct scar resection were performed without electrophysiologic studies, whereas "direct procedures" consisted of either complete endocardial incisions ("encircling endocardial ventriculotomy") or large endocardial resections ("endocardial peel-off" technique) after precise epicardial and endocardial mapping procedures. In Germany, the first to report on intra-operative electrophysiologic mapping for VT treatment were Ostermeyer, Breithardt and Seipel in 1979. In 1981, the Hannover group (Frank, Klein) published their first results of surgical treatment of VT. In 1984, Ostermeyer et al. demonstrated that a partial endocardial incision resulted in more beneficial results with less myocardial damage (8% versus 46%) than applying a complete encircling incision. In 1987, the Düsseldorf group reported treatment results of 93 patients. After 5 years, 77% had no VT recurrence, while total mortality after 1 year was 11% and after 5 years 30%. In 1992, the Hannover group reported results of 147 patients after endocardial resection for VT. Total mortality after 3 years was 27%; recurrence of VT events occurred in 18% of the surviving cohort.The history of surgical procedures for supraventricular tachycardia (SVT), in particular Wolff-Parkinson-White (WPW) syndrome, is even shorter than that of surgery for VT. As early as 1969, Sealy, Gallagher and Cox reported the first cases of surgical intervention for WPW syndrome via endocardial access in cardioplegic arrest. In 1984, Guiraudon and Klein reported on a new procedure with epicardial access to the accessory bundle without cardioplegia in laterally localised conduction pathways. In Germany, too, the groups in Düsseldorf (Ostermeyer, Seipel, Breithardt, Borggrefe) from 1980 and the Hannover group (Frank, Klein and Kallfelz) from 1981 performed surgical procedures for WPW syndrome. In 1987, Borggrefe reported on 18 patients with WPW syndrome and atrial fibrillation who had undergone surgery. After 2 years, 14 of 18 patients had no recurrences of tachycardia; in 1989, Frank, Klein and Kallfelz (Hannover) reported on 10 children (2-14 years) operated on using the cryoablation technique. Between 1984 and 1992, a total of 120 patients with SVT, mostly WPW syndrome, were operated on in Hannover; after 42 months, 12 patients had a recurrence of SVT. Two patients died during the reoperation.

Ventricular tachycardia after myocardial infarction: from arrhythmia surgery to catheter ablation

Ventricular tachycardia due to prior myocardial infarction is caused by reentry. Intraoperative mapping at the time of arrhythmia surgery has shown that the reentry circuits are diverse in size and location. Many circuits are large, extending over several square centimeters. Endocardial excision guided by activation sequence mapping, fractionated sinus rhythm electrograms, or visual identification of scarred subendocardium renders 69% to 95% of patients free from inducible ventricular tachycardia, but with an operative mortality that exceeds 8% at most centers. Catheter ablation is difficult due to limitations of catheter mapping, relatively small size of lesions produced with current techniques, and limited access to intramural and epicardial portions of the reentry circuits. Many problems need to be overcome for catheter ablation to achieve success comparable to that of surgery. At present, only hemodynamically tolerated ventricular tachycardias can be mapped. Progress is being made, and it is likely that catheter ablation will become a viable therapy for subgroups of patients with postmyocardial infarction ventricular tachycardia.

The long-term outcome of visually directed subendocardial resection in patients without inducible or mappable ventricular tachycardia at the time of surgery

INTRODUCTION

In prior studies, 20% to 40% of patients undergoing subendocardial resection (SER) for ventricular tachycardia (VT) could not be mapped intraoperatively because the VT was either noninducible or nonmappable following the ventriculotomy. The optimal surgical approach to such patients is not known.

METHODS AND RESULTS

In this study, we retrospectively compared the long-term survival and functional outcome of 29 patients with VT and prior myocardial infarction who were either noninducible or nonmappable intraoperatively and underwent a visually directed extended SER. These results were then compared to 85 patients who had inducible VT intraoperatively and underwent a map-guided sequential SER. The two patient groups had different clinical characteristics. The visually directed cohort was more likely to be male, experienced fewer VT episodes before surgery, and underwent fewer antiarrhythmic drug trials prior to resection. In addition, the visually directed group had slower VT induced at a preoperative electrophysiologic study and was less likely to present to the operating room in shock or incessant VT than the map-guided group. The postoperative VT clinical recurrence or inducibility rate was 14% in both the visually directed and map-guided groups. The long-term actuarial survival at 1, 3, and 5 years was 93%, 86%, and 75%, respectively, in the visually directed group, compared to 77%, 58%, and 58%, respectively, in the map-guided group (P = 0.06). There were no documented nonfatal recurrences of VT in either group. At 24 months following surgery, 77% of patients who had a visually directed SER were in New York Heart Association Functional Class I or II, compared to 46% of patients who underwent a map-guided SER (P < 0.05).

CONCLUSION

In patients with VT and prior myocardial infarction, the inability to induce or map the VT in the operating room does not preclude a favorable long-term outcome if a visually directed extended SER technique is used.