Background
Catheter ablation is a broadly established therapy technique in the treatment of different types of ventricular arrhythmia (VA). Patients with VA are often multimorbid and preprocedural renal insufficiency is observed frequently. The effect of renal impairment as an independent risk factor on major complications and intrahospital mortality in patients undergoing VA ablation procedures has not been subject of in-depth evaluation because impaired renal function has been an exclusion criteria in previous investigations on this topic.

Methods
We evaluated data from 1417 consecutive patients undergoing 1792 procedures of catheter ablation for VA. For analysis patients were divided into 4 groups according to their stage of renal failure (no renal failure: ≥90 ml · min–1 · 1.73 m–2, mild renal failure: 89–60 ml · min–1 · 1.73 m–2 and moderate renal failure:  59 to 30 ml · min–1 · 1.73 m–2, severe renal failure:  <30 ml · min–1 · 1.73 m–2) and evaluated for the incidence of major complications and death within the groups. Furthermore, a partial effects plot and odds ratio were calculated to investigate the direct effect of decreasing GFR on the endpoint.

Results
1792 procedures of catheter ablation performed in 1417 consecutive patients (965 male (68.1) were analyzed. The population’s mean age was 64.4±16.0 years, including a range from 14 to 94 years.
A total of 109 (6.1%) events of major complication or intrahospital death occurred. We observed a significantly higher risk for major procedural complications and intrahospital death (3.3% vs. 7.2%, p<0.001) in renal failure patients. The risk of suffering from either a major complication or intrahospital death increased significantly from the group with no renal dysfunction compared with the mild renal dysfunction group (3.3% vs. 5.7%, p=0.0287), as well as between the group with moderate and severe renal dysfunction (8.7% vs. 20.5%, p=0.0156), triggered by intrahospital death. Odds ratio and partial effects plot demonstrate correlation of decreasing GFR and a higher probability of major complication or intrahospital death (GFR = 80 to GFR = 30 was 0.461 [95% CI: 0.240, 0.884]). Cardiac tamponade was the most common major complication, while septic shock and postprocedural recurrence of arrhythmia were the most prevalent reasons for intrahospital death.
Furthermore, the groups showed significant differences in prevalence of sustained VT and electrical storm. While the overall prevalence of electrical storm was 11.6%, we observed 23.5% in electrical storm in the patient group with moderate renal dysfunction and a further increase to 31% in the patient group with severe renal dysfunction.

Conclusions
Underlying renal insufficiency is an independent predictor for major complications in VA ablation, as well as postprocedural intrahospital mortality.