“The recurrence rate following VT ablation in structural heart disease remains substantial and thus better endpoints for VT ablation are needed,” Dr. David S. Frankel from Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania told Reuters Health in an email. “In addition to noninducibility of clinical VT at the end of ablation, we show that noninducibility of clinical VT at NIPS is an important endpoint and a step forward in improving outcomes following VT ablation.”
Dr. Frankel and colleagues evaluated the ability of NIPS through the implantable cardioverter-defibrillator several days after VT ablation to identify patients at high risk of recurrence.
Of 200 consecutive patients with VT and structural heart disease undergoing ablation, 11 had clinical VT inducible during programmed stimulation at the end of ablation and 11 exhibited recurrence of spontaneous VT in the days after ablation.
Of the remaining 178 patients, 132 underwent NIPS a mean of 3.1 days after ablation. Clinical VT was inducible in 24 (18.2%) of these patients, and nonclinical VT was inducible in 49 (37.1%). No VT was inducible in 59 (44.7%).
OF the 24 patients with inducible clinical VT at NIPS, 6 had not undergone programmed stimulation at the end of ablation, 6 had nonclinical VT induced at the end of ablation, and 12 had no VT induced at the end of ablation.
During the first year after ablation, significantly more patients with clinical VT (21%) or nonclinical VT (24%) inducible at NIPS died, compared with patients in whom no VT was inducible (3%)(p=0.01).
In Kaplan-Meier survival analysis, 1-year VT-free survival was markedly decreased (<30%) among patients with inducible clinical VT at NIPS, with 67% of these patients experiencing recurrences with ICD shocks and 33% with VT storm.
One-year VT-free survival was also significantly lower for patients with inducible nonclinical VT (65%) than for patients with no VT inducible at NIPS (85%)(p=0.01).
Factors independently associated with VT recurrence in multivariate analysis included no programmed stimulation at the end of ablation, inducible clinical VT at the end of ablation, NIPS not performed, and inducible clinical VT at NIPS.
“Patients with clinical VT inducible at NIPS have a very high rate of recurrence during follow-up, and therefore we recommend repeat catheter ablation to eliminate the clinical VT, followed by repeat NIPS to ensure that the clinical VT has in fact been eliminated,” Dr. Frankel said.
“Noninducibility of any VT at NIPS can be used to reassure patients that their risk of recurrence is low,” Dr. Frankel said.
Dr. Frankel added, “We are prospectively comparing ‘NIPS guided treatment’ to standard of care. Our hypothesis is that NIPS guided treatment will identify patients in need of additional ablation and will ultimately result in lower recurrence rates in follow-up. NIPS also provides useful information regarding ICD programming and antiarrhythmic drugs.”
“Additional studies are clearly necessary to further delineate the role of NIPS to better understand the prediction of VT recurrence after catheter ablation and to improve the management and outcome of such patients,” write Dr. Gerhard Hindricks and Dr. Christopher Piorkowski from University of Leipzig, Leipzig, Germany in a related editorial.
“As a word of caution,” they note, “in the past, programmed stimulation has failed many times to predict efficacy of antiarrhythmic drugs, to identify candidates for implantable cardioverter-defibrillator implantation, and to identify patients with high risk for sudden cardiac death. Hopefully, history will not repeat with NIPS.”
“As long as we do not have convincing studies presenting better endpoints,” the editorial concludes, “we should continue to use noninducibility as the endpoint of VT catheter ablation—potentially supported by NIPS.”