Catheter ablation of postinfarction ventricular tachycardia: ten-year trends in utilization, in-hospital complications, and in-hospital mortality in the United States

Ventricular Tachycardias

Ventricular tachyarrhythmia is an important cause of morbidity and sudden death. Although implantable cardioverter-defibrillator (ICD) reduces the risk of arrhythmic death, ICD therapies are associated with an increased mortality and worsening quality of life. Antiarrhythmic drugs may be effective in preventing arrhythmia recurrences but have an increased adverse effects and non-cardiac mortality. Catheter ablation has evolved into an effective intervention in patients with and without structural heart disease. This monograph is a collection of thought-provoking challenging case scenarios. These cases emphasize important electrocardiographic and anatomic features, illustrating crucial diagnostic maneuvers, mapping techniques, imaging integration, as well as formulating the ablation strategies.

Ablation of Ventricular Tachycardia in Patients with Ischemic Cardiomyopathy

Ventricular tachycardias (VTs) occurring after prior myocardial infarction are usually caused by reentrant circuits formed by surviving myocardial bundles. Although part of the reentrant circuits may be located in the midmyocardium or epicardium, most of the VTs can be safely and successfully ablated by endocardial ablation targeting the late potentials/local abnormal ventricular activation, which are surrogates for the surviving myocardial bundles. A combination of activation, substrate, pace, and entrainment mapping, as well as the use of contact force catheters, further improves ablation success and safety.

Mobile thrombus on cardiac implantable electronic device leads of patients undergoing cardiac ablation: incidence, management, and outcomes

PURPOSE

The rates of cardiovascular implantable electronic device (CIED) implantations and cardiac ablation procedures are increasing worldwide. To date, the management of CIED lead thrombi in the peri-ablation period remains undefined and key clinical management questions remained unanswered. We sought to describe the clinical course and management strategies of patients with a CIED lead thrombus detected in the peri-ablative setting.

METHODS

We performed a retrospective analysis of all patients who underwent a cardiac ablation procedure at Mayo Clinic Rochester from 2000 to 2014. Patients were included in our study cohort if they had documented CIED lead thrombus noted on peri-ablation imaging studies. Electronic medical records were reviewed to determine the overall management strategy, outcomes, and embolic complications in these patients.

RESULTS

Our overall cohort included 1833 patients, with 27 (1.4 %) having both cardiac ablation procedures as well as CIED lead thrombus detected on imaging. Of these 27 patients, 21 were male (77 %), and the mean age was 59.2 years. The mean duration of follow-up was 16.5 months (range 3 days-48.3 months). Anticoagulation was an effective therapeutic strategy, with 11/14 (78.6 %) patients experiencing either resolution of the thrombus or reduction in size on re-imaging. For atrial fibrillation ablation, the most common management strategy was a deferment in ablation with initiation/intensification of anticoagulation medication. For ventricular tachycardia ablations, most procedures involved a modified approach with the use of a retrograde aortic approach to access the left ventricle. No patient had any documented embolic complications.

CONCLUSIONS

The incidence of lead thrombi in patients undergoing an ablation was small in our study cohort (1.4 %). Anticoagulation and deferral of ablation represented successful management strategies for atrial fibrillation ablation. For patients undergoing ventricular tachycardia ablation, a modified approach using retrograde aortic access to the ventricle was successful. In patients who are not on warfarin anticoagulation at the time of thrombus detection, we recommend initiation of this medication, with a goal INR of 2-3. For patients on warfarin at the time of thrombus detection, we recommend an intensification of anticoagulation with a goal INR of 3.0.

Mortality prediction using a modified Seattle Heart Failure Model may improve patient selection for ventricular tachycardia ablation

BACKGROUND

Catheter ablation is frequently used as a palliative option to reduce shock burden in patients with ventricular tachycardia (VT). A risk prediction tool that accurately predicts short-term survival could improve patient selection for VT ablation.

OBJECTIVE

The objective of the study is to assess utility of the Seattle Heart Failure Model (SHFM) to predict 6-month mortality in patients undergoing VT ablation.

METHODS

Data on patients who underwent VT ablation at 2 tertiary institutions were retrospectively compiled. The SHFM score at the time of ablation, including 2 added VT variables, was used to predict 6-month mortality. The predicted number of deaths was compared to the observed number to assess model calibration. Model discrimination of those who died within 6 months was assessed by both K- and C-statistics.

RESULTS

Mean age of the 243 patients was 63 ± 12 years; 89% were male. Mean SHFM score for the cohort was 1.3 ± 1.3. The Kaplan-Meier probability of death within 6 months was 14% (34 patients). The number of deaths estimated by the SHFM at 6 months was 31 (13%) giving a predicted to observed ratio of 0.91 (95% CI 0.64-1.30). The K-statistic for 6-month mortality predictions was 0.77 (95% CI 0.73-0.81), whereas the C-statistic was 0.84 (95% CI 0.78-0.92). Patients with an SHFM score ≥4.0 had an estimated positive predictive value of 80% (95% CI 28%-99%) for dying within 6 months of VT ablation.

CONCLUSION

The SHFM was well calibrated to a sample of patients who underwent VT ablation and provided good discrimination of short-term deaths. This model could be useful as a prognostic tool to improve patient selection for VT ablation.

Management of pace-terminated ventricular arrhythmias

An implantable-cardioverter defibrillator (ICD) can terminate ventricular arrhythmias by delivering a shock or by antitachycardia pacing (ATP). The ATP works by capturing the excitable gap and disrupting re-entrant ventricular arrhythmias. Multiple studies have demonstrated that ATP is successful at terminating ventricular tachycardia (VT). Shocks from the ICD are associated with higher mortality. The data are conflicting about whether appropriate ATP is associated with higher mortality. In a patient with VT that is treated by ATP, the patient's guideline-based heart failure medications should be maximized. The use of VT ablation after appropriate and successful ATP requires additional studies.

Safety of ventricular tachycardia ablation in clinical practice: findings from 9699 hospital discharge records

BACKGROUND

Outcomes of ventricular tachycardia (VT) ablation have been described in clinical trials and single-center studies. We assessed the safety of VT ablation in clinical practice.

METHODS AND RESULTS

Using administrative hospitalization data between 1994 and 2011, we identified hospitalizations with primary diagnosis of VT (International Classification of Diseases-9 Clinical Modification code: 427.1) and cardiac ablation (International Classification of Diseases-9 Clinical Modification code: 37.34). We quantified in-hospital adverse events (AEs), including death, stroke, intracerebral hemorrhage, pericardial complications, hematoma or hemorrhage, blood transfusion, or cardiogenic shock. Secondary outcomes included major AEs (stroke, tamponade, or death) and death. Multivariable mixed effects models identified patient and hospital characteristics associated with AEs. Of 9699 hospitalizations with VT ablations (age, 56.5 ± 17.6; 60.1% men), AEs were reported in 825 (8.5%), major AEs in 295 (3.0%), and death in 110 (1.1%). Heart failure had the strongest association with death (odds ratio, 5.52; 95% confidence interval, 2.97-10.3) and major AE (odds ratio, 2.99; 95% confidence interval, 2.15-4.16). Anemia (odds ratio, 4.84; 95% confidence interval, 3.79-6.19) and unscheduled admission (odds ratio, 1.64; 95% confidence interval, 1.37-1.97) were associated with AEs. During the study period, incidence of AEs increased from 9.2% to 12.8% as did the burden of AE risk factors (0.034 patient/y; P < 0.001). Hospital volume > 25 cases/y was associated with fewer AEs compared with lower volume centers (6.4% versus 8.8%; P = 0.008).

CONCLUSIONS

VT ablation-associated AE rates in clinical practice are similar to those reported in the literature. Over time rates have increased as have the number of AE risk factors per patient. Ablations done electively and at hospitals with higher procedural volume are associated with lower incidence of AEs.