Natural History of Myocardial Injury After COVID-19 Vaccine-Associated Myocarditis.

BACKGROUND: Acute myocarditis is a rare complication of mRNA-based COVID-19 vaccination. Little is known about the natural history of this complication. METHODS: Baseline and convalescent (≥ 90 days) cardiac magnetic resonance (CMR) imaging assessments were performed in 20 consecutive patients meeting Updated Lake Louise Criteria for acute myocarditis within 10 days of mRNA-based vaccination. CMR-based changes in left ventricular volumes, mass, ejection fraction (LVEF), markers of tissue inflammation (native T1 and T2 mapping), and fibrosis (late gadolinium enhancement [LGE] and extracellular volume [ECV]) were assessed between baseline and convalescence. Cardiac symptoms and clinical outcomes were captured. RESULTS: Median age was 23.1 years (range 18-39 years), and 17 (85%) were male. Convalescent evaluations were performed at a median (IQR) 3.7 (3.3-6.2) months. The LVEF showed a mean 3% absolute improvement, accompanied by a 7% reduction in LV end-diastolic volume and 5% reduction in LV mass (all P < 0.015). Global LGE burden was reduced by 66% (P < 0.001). Absolute reductions in global T2, native T1, and ECV of 2.1 ms, 58 ms, and 2.9%, repectively, were documented (all P ≤ 0.001). Of 5 patients demonstrating LVEF ≤ 50% at baseline, all recovered to above this threshold in convalescence. A total of 18 (90%) patients showed persistence of abnormal LGE although mean fibrosis burden was < 5% of LV mass in 85% of cases. No patient experienced major clinical outcomes. CONCLUSIONS: COVID-19 mRNA vaccine-associated myocarditis showed rapid improvements in CMR-based markers of edema, contractile function, and global LGE burden beyond 3 months of recovery in this young patient cohort. However, regional fibrosis following edema resolution was commonly observed, justifying need for ongoing surveillance.

Right Ventricular Mass 12 Years after Osteosarcoma: Multimodality Imaging with Pathologic Correlation.

The authors report a 27-year-old woman with a remote left femoral osteosarcoma and amputation above the left knee who presented with a large right ventricular mass. Initial evaluation with thoracic CT was inconclusive regarding thrombus versus tumor, but metastatic osteosarcoma was suggested by findings at transthoracic echocardiography, cardiac CT, and cardiac MRI. The patient underwent tumor debulking, and osteosarcoma was confirmed with pathologic examination. She responded to chemotherapy, which resulted in reduction in size of the residual right ventricular tumor and of a few pulmonary metastases. Following induction chemotherapy, patient remains well undergoing maintenance therapy with an oral tyrosine kinase inhibitor. Keywords: CT, Echocardiography, MR Imaging, Intraoperative, Cardiac, Heart, Right Ventricle, Imaging Sequences, Metastases, Oncology Supplemental material is available for this article. © RSNA, 2021.

Impact of empagliflozin on right ventricular parameters and function among patients with type 2 diabetes.

BACKGROUND: Sodium-glucose cotransporter 2 (SGLT2) inhibition reduces cardiovascular events in type 2 diabetes (T2DM) and is associated with a reduction in left ventricular (LV) mass index. However, the impact on right ventricular (RV) remodeling is unknown. Accordingly, the objective of this study was to assess the impact of SGLT2 inhibition on RV parameters and function in T2DM and coronary artery disease (CAD). METHODS: In EMPA-HEART CardioLink-6, 97 patients with T2DM and CAD were randomly assigned to empagliflozin 10 mg (n = 49) once daily or placebo (n = 48). Cardiac magnetic resonance imaging was performed at baseline and after 6 months. RV mass index (RVMi), RV end-diastolic and end-systolic volume index (RVEDVi, RVESVi) and RV ejection fraction (RVEF) were assessed in blinded fashion. RESULTS: At baseline, mean RVMi (± SD) (11.8 ± 2.4 g/m2), RVEF (53.5 ± 4.8%), RVEDVi (64.3 ± 13.2 mL/m2) and RVESVi (29.9 ± 6.9 mL/m2) were within normal limits and were similar between the empagliflozin and placebo groups. Over 6 months, there were no significant differences in RVMi (- 0.11 g/m2, [95% CI - 0.81 to 0.60], p = 0.76), RVEF (0.54%, [95% CI - 1.4 to 2.4], p = 0.58), RVEDVi (- 1.2 mL/m2, [95% CI - 4.1 to 1.7], p = 0.41) and RVESVi (- 0.81 mL/m2, [95% CI - 2.5 to 0.90], p = 0.35) in the empaglifozin group as compared with the placebo group. In both groups, there was no significant correlation between RVMi and LVMi changes from baseline to 6 months. CONCLUSIONS: In this post-hoc analysis, SGLT2 inhibition with empagliflozin had no impact on RVMi and RV volumes in patients with T2DM and CAD. The potentially differential effect of empagliflozin on the LV and RV warrants further investigation. CLINICAL TRIAL REGISTRATION: URL:  https://www.clinicaltrials.gov/ct2/show/NCT02998970?cond=NCT02998970&draw=2&rank=1 . Unique identifier: NCT02998970.

2021 Update on Safety of Magnetic Resonance Imaging: Joint Statement From Canadian Cardiovascular Society/Canadian Society for Cardiovascular Magnetic Resonance/Canadian Heart Rhythm Society.

Magnetic resonance imaging (MRI) is often considered the gold-standard test for characterizing cardiac as well as noncardiac structure and function. However, many patients with cardiac implantable electronic devices (CIEDs) and/or severe renal dysfunction are unable to undergo this test because of safety concerns. In the past 10 years, newer-generation CIEDs and gadolinium-based contrast agents (GBCAs) as well as coordinated care between imaging and heart rhythm device teams have mitigated risk to patients and improved access to MRI at many hospitals. The purpose of this statement is to review published data on safety of MRI in patients with conditional and nonconditional CIEDs in addition to patient risks from older and newer GBCAs. This statement was developed through multidisciplinary collaboration of pan-Canadian experts after a relevant and independent literature search by the Canadian Agency for Drugs and Technologies in Health. All recommendations align with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Key recommendations include: (1) the development of standardized protocols for patients with a CIED undergoing MRI; (2) patients with MRI nonconditional pacemakers and pacemaker dependency should be programmed to asynchronous mode and those with MRI nonconditional transvenous defibrillators should have tachycardia therapies turned off during the scan; and (3) macrocyclic or newer linear GBCAs should be used in preference to older GBCAs because of their better safety profile in patients at higher risk of nephrogenic systemic fibrosis.

2021 update on safety of magnetic resonance imaging: joint statement from Canadian Cardiovascular Society/ Canadian Society for Cardiovascular Magnetic Resonance/ Canadian Heart Rhythm Society

Magnetic resonance imaging (MRI) is often considered the gold-standard test for characterizing cardiac as well as noncardiac structure and function. However, many patients with cardiac implantable electronic devices (CIEDs) and/or severe renal dysfunction are unable to undergo this test because of safety concerns. In the past 10 years, newer-generation CIEDs and gadolinium-based contrast agents (GBCAs) as well as coordinated care between imaging and heart rhythm device teams have mitigated risk to patients and improved access to MRI at many hospitals. The purpose of this statement is to review published data on safety of MRI in patients with conditional and nonconditional CIEDs in addition to patient risks from older and newer GBCAs. This statement was developed through multidisciplinary collaboration of pan-Canadian experts after a relevant and independent literature search by the Canadian Agency for Drugs and Technologies in Health. All recommendations align with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Key recommendations include: (1) the development of standardized protocols for patients with a CIED undergoing MRI; (2) patients with MRI nonconditional pacemakers and pacemaker dependency should be programmed to asynchronous mode and those with MRI nonconditional transvenous defibrillators should have tachycardia therapies turned off during the scan; and (3) macrocyclic or newer linear GBCAs should be used in preference to older GBCAs because of their better safety profile in patients at higher risk of nephrogenic systemic fibrosis.

Lipid Testing, Lipid-Modifying Therapy, and PCSK9 (Proprotein Convertase Subtilisin-Kexin Type 9) Inhibitor Eligibility in 27 979 Patients With Incident Acute Coronary Syndrome.

BACKGROUND: While registry-based studies have shown that as many as 1 in 2 patients with stable atherosclerotic cardiovascular disease would be eligible for PCSK9i (proprotein convertase subtilisin-kexin type 9 inhibitor) therapy, this has not been studied in a large population-based postacute coronary syndrome (ACS) cohort. METHODS: We examined lipid testing performed in hospital or within 90 days of discharge and lipid-lowering therapies dispensed within 90 days of discharge in patients surviving for at least 1 year after their first ACS between 2012 and 2018 in the province of Alberta, Canada. We estimated the proportion of patients eligible for PCSK9i and the expected benefits of treatment. RESULTS: Of the 27 979 patients (median age 64.0 years, 29.3% female, 28.0% diabetic), 3750 (13.4%) did not have lipid testing in-hospital or within 90 days postdischarge. Untested patients were more likely to be older, female, from rural areas, to have more comorbidities, to already be on cardioprotective therapies, to present with unstable angina, and were less likely to have invasive interventions (all P<0.0001). Of the 24 229 tested, 18 767 (77.5%) had at least one lipid value above guideline-recommended threshold (LDL [low-density lipoprotein] ≥1.8 mmol/L [70 mg/dL] and non-HDL [high-density lipoprotein] ≥2.6 mmol/L [100 mg/dL]), of which 7284 (38.8%) did not have repeat testing within the year after discharge. Lipid testing in hospital was associated with higher rates of initiation or escalation of statin therapy within 90 days of their ACS (adjusted odds ratio, 2.13 [95% CI, 1.97-2.30). In total, 9592 patients (39.6% of the tested cohort) would be eligible for PCSK9i use, which could result in 184 fewer cardiovascular events over 3.4 years, including cardiovascular death, nonfatal ACS (myocardial infarction or unstable angina requiring hospitalization), and ischemic stroke. CONCLUSIONS: Within 90 days of incident ACS, ≈80% of patients did not meet guideline-recommended lipid thresholds and more than one-third would potentially be eligible for PCSK9i.

Pulse pressure in acute coronary syndromes: Comparative prognostic significance with systolic blood pressure.

BACKGROUND: Pulse pressure is a readily available vital sign that has been shown to independently predict outcomes in several cardiovascular disease states. We investigated the prognostic significance of pulse pressure (PP) and systolic blood pressure (SBP) among patients with acute coronary syndromes (ACS). METHODS: A total of 14,514 patients with ACS in the prospective, multicentre Global Registry of Acute Coronary Events (GRACE), expanded GRACE (GRACE-2) and Canadian Registry of Acute Coronary Events (CANRACE) were stratified by initial PP on presentation. Patient characteristics and in-hospital outcomes were compared by PP quartiles and the independent prognostic significance of PP for in-hospital mortality was quantified. We compared the discriminative ability (c-statistic) of models incorporating either PP or SBP. RESULTS: Patients with higher PPs were older, more frequently female and had higher prevalence rates of conventional cardiovascular risk factors (all p < 0.01). Lower PP was associated with ST-segment elevation myocardial infarction presentation, higher GRACE risk scores and higher rates of adverse in-hospital outcomes (p < 0.001). PP was strongly correlated with SBP (Pearson's correlation coefficient = 0.79, p < 0.001). After adjustment for other GRACE risk model predictors, lower PP was independently associated with in-hospital mortality (first vs. fourth quartile [reference]: adjusted odds ratio 2.57, 95% confidence interval 1.80-3.67). The c-statistic was slightly higher for the multivariable model incorporating SBP as compared to the model with PP (0.868 vs. 0.864, respectively, p = 0.028) for in-hospital mortality. CONCLUSION: Higher presenting PP is associated with increased age and more prevalent cardiovascular risk factors, whereas patients with lower PP present with worse clinical characteristics and in-hospital outcomes. Lower PP is an independent adverse prognosticator in ACS. However, PP did not improve the discriminatory performance of the GRACE risk score compared with SBP.

Electrocardiographic Findings in Patients With Acute Coronary Syndrome Presenting With Out-of-Hospital Cardiac Arrest.

We sought to characterize presenting electrocardiographic findings in patients with acute coronary syndromes (ACSs) and out-of-hospital cardiac arrest (OHCA). In the Global Registry of Acute Coronary Events and Canadian ACS Registry I, we examined presenting and 24- to 48-hour follow-up ECGs (electrocardiogram) of ACS patients who survived to hospital admission, stratified by presentation with OHCA. We assessed the prevalence of ST-segment deviation and bundle branch blocks (assessed by an independent ECG core laboratory) and their association with in-hospital and 6-month mortality among those with OHCA. Of the 12,040 ACS patients, 215 (1.8%) survived to hospital admission after OHCA. Those with OHCA had higher presenting rates of ST-segment elevation, ST-segment depression, T-wave inversion, precordial Q-waves, left bundle branch block (LBBB), and right bundle branch block (RBBB) than those without. Among patients with OHCA, those with ST-segment elevation had significantly lower in-hospital mortality (20.9% vs 33.0%, p = 0.044) and a trend toward lower 6-month mortality (27% vs 39%, p = 0.060) compared with those without ST-segment elevation. Conversely, among OCHA patients, LBBB was associated with significantly higher in-hospital and 6-month mortality rates (58% vs 22%, p <0.001, and 65% vs 28%, p <0.001, respectively). ST-segment depression and RBBB were not associated with either outcome. Sixty-three percent of bundle branch blocks (RBBB or LBBB) on the presenting ECG resolved by 24 to 48 hours. In conclusion, compared with ACS patients without cardiac arrest, those with OHCA had higher rates of ST-segment elevation, LBBB, and RBBB on admission. Among OHCA patients, ST-segment elevation was associated with lower in-hospital mortality, whereas LBBB was associated with higher in-hospital and 6-month mortality.

Relationship between changes in blood pressure and left ventricular mass over 1 year in end-stage renal disease.

OBJECTIVE: The optimal timing of blood pressure (BP) measurement is not firmly established for patients undergoing hemodialysis. We sought to assess which BP measurement change best correlates with changes in left ventricular mass index (LVMI) over 1 year in patients with end-stage renal disease. METHODS: Fifty-seven patients were included in a prospective cohort study comparing the cardiovascular impact of conversion to in-center nocturnal hemodialysis versus continuing conventional hemodialysis. BP measurements were recorded at different time points (predialysis, after initiation of dialysis, at the intradialytic nadir, and postdialysis) during dialysis sessions over 12 weeks at baseline and after 1-year follow-up. LVMI was independently measured by a single blinded reader using cardiac magnetic resonance imaging at baseline and 1 year. RESULTS: Overall, the mean LVMI was 69.9 g/m (standard deviation 15.9) at baseline and 69.6 g/m (standard deviation 16.0) at 1 year. The change in initiation mean arterial pressure (MAP) most strongly correlated with the change in LVMI (Pearson correlation coefficient r = 0.71, P < 0.001). The relationship was similar in both dialysis groups and in multivariable analysis. In pairwise comparisons, initiation MAP was more strongly correlated with the change in LVMI than nadir and postdialysis measurements (all P < 0.05). However, the correlation was not stronger than predialysis SBP (P = 0.33). CONCLUSION: The change in initiation MAP correlated best with the change in LVMI over 1 year in patients undergoing hemodialysis. Further studies are needed to determine whether it represents a potentially useful treatment target to prevent adverse ventricular remodeling, thereby improving cardiovascular outcome.ClinicalTrials.gov Identifier: NCT00718848.

Prognostic value of dynamic electrocardiographic T wave changes in non-ST elevation acute coronary syndrome.

OBJECTIVE: To assess the relationship between the evolution of T wave inversion (TWI) on the 24-48 h postadmission ECG and the patient characteristics, management and clinical outcomes among those with non-ST elevation acute coronary syndrome (NSTE-ACS). METHODS: We evaluated admission and 24-48 h follow-up ECGs of 7201 patients with NSTE-ACS from the prospective, multicentre Global Registry of Acute Coronary Events (GRACE) and Canadian ACS Registry I. We performed multivariable analyses to determine the association between new TWI (on follow-up ECG only), resolved TWI (on admission ECG only) and persistent TWI (on both admission and follow-up ECG) and inhospital and cumulative 6-month all-cause mortality. RESULTS: Patients with TWI were older, more likely to have cardiovascular risk factors, higher Killip class and GRACE risk scores. After adjustment for known prognostic factors, compared with patients presenting without TWI, new TWI was associated with significantly lower inhospital mortality (OR=0.60, 95% CI 0.38 to 0.95, p=0.029), whereas resolved (OR=1.06, 95% CI 0.65 to 1.75, p=0.81) and persistent (OR=0.73, 95% CI 0.48 to 1.11, p=0.14) TWI did not predict inhospital mortality. No TWI pattern independently predicted inhospital adverse cardiovascular events or cumulative 6-month mortality. In contrast, ST depression on the admission and follow-up ECG were independent predictors of inhospital and 6-month mortality. CONCLUSIONS: Across the spectrum of NSTE-ACS, TWI within 48 h of presentation was associated with high-risk clinical features, but its presence or dynamic change did not provide additional prognostic value beyond other established clinical predictors.

Myocardial injury secondary to ICD shocks: insights from patients with lead fracture.

BACKGROUND: Patients who receive appropriate implantable cardioverter defibrillator (ICD) shocks have a subsequent adverse prognosis. Most data suggest that patients with inappropriate ICD shocks also have a subsequent adverse prognosis, although this is more controversial. The shocks may be an epiphenomenon, that is, a marker of underlying disease progression; however, it cannot be excluded that shocks cause direct myocardial damage. This latter question is difficult to clarify as the arrhythmia provoking the shock can also cause troponin release. Inappropriate shocks secondary to lead fracture are an ideal situation to examine this question; any troponin release in an otherwise well and hemodynamically stable patient, is likely due directly to the shocks. METHODS: All patients with Fidelis lead fracture admitted to our institution with inappropriate shocks were included in this study. Troponin (I or T) was considered positive if the level was above the 99th percentile reference cutoff. RESULTS: Elevated troponin levels were recorded in 16 of 22 patients (73%). Patients with elevated troponin received a higher number of shocks (20.3 ± 30.1 vs 5.3 ± 4.8, P = 0.07) compared with patients with normal troponin. Very elevated troponin levels (>0.8 mcg/L) were seen in five of 22 (22%) patients. The mean peak troponin level for these five patients was 7.06 ± 8.56 mcg/L; two patients had troponin levels that would be expected from a medium-sized myocardial infarction or severe myocarditis. CONCLUSION: Troponin elevation occurred in the majority of our patients after inappropriate ICD discharges secondary to lead fracture. This indicates that ICD shocks can cause myocardial injury.

Incidence of very high defibrillation thresholds (DFT) and efficacy of subcutaneous (SQ) array insertion during implantable cardioverter defibrillator (ICD) implantation.

BACKGROUND: The incidence, risk factors, and management of very high defibrillation thresholds (DFTs) during present-day implantable cardioverter defibrillator (ICD) testing are not well known. OBJECTIVES: The purpose of this study was to assess (1) the incidence of very high DFTs and (2) the efficacy/safety of routinely adding a subcutaneous (SQ) array for these patients. METHODS: The study evaluated patients undergoing first-time ICD implantation at Southlake Regional Healthcare Centre from January 2006 to December 2007. All implanted ICDs had a maximal output of 35 J. Patients with DFTs greater than a 10-J safety margin from maximum output were considered to have very high readings and underwent SQ array insertion after other attempts at lowering DFT (group I). These patients were compared with the rest of the patients who had acceptable DFTs (group II) using both univariate and multivariate logistic regression analysis. Outcomes of array insertion were also assessed. RESULTS: A total of 313 patients underwent first-time ICD implantation during the analysis period. Of those, 16 (5.1%) had very high DFTs (group I). By univariate analysis, advanced New York Heart Association class (3 or 4), congestive heart failure hospitalization, non-ischemic cardiomyopathy, amiodarone use, implant of a biventricular device, and highest quartile of left ventricular (LV) chamber enlargement were all significant predictors of very high DFTs (p < 0.05). By multivariate analysis, only amiodarone use [odds ratio (OR) = 10.3, 95% confidence interval (95% CI) = 3.7-32.6] and being in the highest quartile for LV diastolic diameter [OR = 5.4, 95% CI = 1.4-20.8] predicted very high DFT. In all 16 cases, other methods to lower DFT prior to array insertion were attempted but failed for all patients: reversing shock polarity (n = 15), removing the superior vena cava coil (n = 14), reprogramming shock waveform (n = 9), and repositioning right ventricular lead (n = 9). Addition of the array successfully decreased DFT to within safety margin for all patients (33 ± 2 vs 21 ± 5 J, p = 0.02). Complication due to array insertion occurred in one patient (pneumothorax). CONCLUSIONS: Very high DFTs occur in about 5% of patients undergoing ICD implantation and may be predicted by LV dilation and amiodarone use. SQ array insertion reliably corrects this problem over other interventions with a low rate of procedural complication.

Incidence of left ventricular function improvement after primary prevention ICD implantation for non-ischaemic dilated cardiomyopathy: a multicentre experience.

BACKGROUND: The SCD-HeFT study demonstrated a benefit of primary prevention implantable cardioverter-defibrillator (ICD) implantation in patients with non-ischaemic dilated cardiomyopathy (NIDCM). However, NIDCM may improve spontaneously, even after waiting 6-9 months on optimal medical treatment. OBJECTIVE: To assess the incidence of left ventricular (LV) function improvement in patients receiving primary prevention ICDs for NIDCM. METHODS: All patients with NIDCM receiving primary prevention ICDs (non-cardiac resynchronisation therapy) from 2005 to the present at our institutions were retrospectively studied. All patients had NIDCM confirmed by a lack of significant stenoses on coronary angiography, a lack of significant valvular abnormalities on echo, and LV dysfunction with ejection fraction (EF) <35%. All patients had to have had a diagnosis of NIDCM for at least 9 months and be receiving optimal medical treatment for at least 3 months before implant according to the guidelines. All patients had at least New York Heart Association (NYHA) II symptoms. Baseline and follow-up EF was documented by quantitative echo and/or multi-gated acquisition scan. RESULTS: 332 patients were identified by a database search. Patients were aged 67+/-11 years, 75% of them were male, NYHA 2.3+/-0.7, with EF 25+/-13%, and LV diastolic diameter 61+/-10 mm. Time from initial NIDCM diagnosis to implant was 11+/-6 months and duration of medical treatment before implant was 8+/-5 months. Treatment at the time of implant included ACE inhibitors or ARBs (85%), beta blockers (77%), spironolactone (53%), loop diuretic (63%) and digoxin (50%). Repeat EF assessment was available in 309/332 (93%) 8+/-6 months after implant. EF improved to >35% in 37/309 (12%) patients. Patients who improved had a shorter time from diagnosis to implant (9+/-3 vs 13+/-5 months respectively, p=0.03). No other significant predictors were identified for patients with improved EF. CONCLUSIONS: In spite of following guidelines for implantation of primary prevention ICDs in patients with NIDCM, a substantial number of patients (12%) experience improvement in LV function to levels above those recommended for ICD implant. A shorter time from diagnosis to implant may predict post-implant improvement.

Predictors of appropriate implantable cardioverter defibrillator (ICD) therapy in primary prevention patients with ischemic and nonischemic cardiomyopathy.

BACKGROUND: We sought to assess predictors of appropriate implantable cardioverter defibrillator (ICD) therapy in patients receiving primary prevention ICDs. METHODS: Four hundred twenty-one consecutive patients (ischemic and nonischemic) undergoing primary prevention ICD implantation were studied. Patients were grouped based on the presence/absence of appropriate ICD therapy. Summary data and stored electrograms from ICDs were reviewed to determine appropriateness of therapy. Predictors of therapy were assessed by both univariate and multivariate Cox regression analysis. RESULTS: Of 421 primary prevention patients undergoing ICD implantation, 79 (19%) had received appropriate ICD therapies. By univariate comparison, nonsustained ventricular tachycardia (NSVT), male sex, left ventricle diastolic diameter (LVDD), and hypertension were all significant predictors for ICD therapy over a mean follow-up time of 751 +/- 493 days (P

Dofetilide is safe and effective in preventing atrial fibrillation recurrences in patients accepted for catheter ablation.

AIMS: The aim of this study was to assess the safety and efficacy of dofetilide among patients refractory to other anti-arrhythmic drugs (AADs) and accepted for atrial fibrillation (AF) ablation. METHODS AND RESULTS: One hundred and twenty-seven of 454 patients (69% male, 58% paroxysmal, age 60 +/- 10 years, AF duration 8 +/- 7 years) scheduled for AF ablation between February 2004 and May 2008 were treated with dofetilide. Patients had failed 1.9 +/- 1.1 AADs. Anti-arrhythmic drugs were stopped five half-lives before ablation and 3 months for amiodarone. Patients were followed for 15 +/- 7 months with routine and symptom-driven monitoring. Success was defined as no further AF and partial success as a 50% reduction in frequency/duration of AF episodes. Thirty-six patients started dofetilide 158 +/- 167 days before ablation: 9 had no improvement, 16 experienced partial success, 8 had no further AF, and 2 improved enough to forgo ablation. Seventy-one patients started dofetilide immediately following ablation, of which 14 had no improvement, 22 experienced partial success, and 32 had no further AF. Twenty patients started dofetilide 119 +/- 153 days post-ablation, of which four had no improvement, seven experienced partial success, and nine had no further AF. Six patients discontinued dofetilide during initiation for QT prolongation. CONCLUSION: Dofetilide appears safe and effective in preventing AF in patients refractory to other AADs undergoing catheter ablation.