Incidental LV LGE on CMR Imaging in Atrial Fibrillation Predicts Recurrence After Ablation Therapy

Pre- and post-procedural cardiac imaging (computed tomography and magnetic resonance imaging) in electrophysiology: a clinical consensus statement of the European Heart Rhythm Association and European Association of Cardiovascular Imaging of the European Society of Cardiology

Imaging using cardiac computed tomography (CT) or magnetic resonance (MR) imaging has become an important option for anatomic and substrate delineation in complex atrial fibrillation (AF) and ventricular tachycardia (VT) ablation procedures. Computed tomography more common than MR has been used to detect procedure-associated complications such as oesophageal, cerebral, and vascular injury. This clinical consensus statement summarizes the current knowledge of CT and MR to facilitate electrophysiological procedures, the current value of real-time integration of imaging-derived anatomy, and substrate information during the procedure and the current role of CT and MR in diagnosing relevant procedure-related complications. Practical advice on potential advantages of one imaging modality over the other is discussed for patients with implanted cardiac rhythm devices as well as for planning, intraprocedural integration, and post-interventional management in AF and VT ablation patients. Establishing a team of electrophysiologists and cardiac imaging specialists working on specific details of imaging for complex ablation procedures is key. Cardiac magnetic resonance (CMR) can safely be performed in most patients with implanted active cardiac devices. Standard procedures for pre- and post-scanning management of the device and potential CMR-associated device malfunctions need to be in place. In VT patients, imaging-specifically MR-may help to determine scar location and mural distribution in patients with ischaemic and non-ischaemic cardiomyopathy beyond evaluating the underlying structural heart disease. Future directions in imaging may include the ability to register multiple imaging modalities and novel high-resolution modalities, but also refinements of imaging-guided ablation strategies are expected.

Prognostic Role of Multiparametric Cardiac Magnetic Resonance in Neo Transfusion-Dependent Thalassemia

BACKGROUND

We prospectively evaluated the predictive value of multiparametric cardiac magnetic resonance (CMR) for cardiovascular complications in non-transfusion-dependent β-thalassemia (β-NTDT) patients who started regular transfusions in late childhood/adulthood (neo β-TDT).

METHODS

We considered 180 patients (38.25 ± 11.24 years; 106 females). CMR was used to quantify cardiac iron overload, biventricular function, and atrial dimensions, and to detect left ventricular (LV) replacement fibrosis.

RESULTS

During a mean follow-up of 76.87 ± 41.60 months, 18 (10.0%) cardiovascular events were recorded: 2 heart failures, 13 arrhythmias (10 supraventricular), and 3 cases of pulmonary hypertension. Right ventricular (RV) end-diastolic volume index (EDVI), RV mass index (MI), LV replacement fibrosis, and right atrial (RA) area index emerged as significant univariate prognosticators of cardiovascular complications. The low number of events prevented us from performing a multivariable analysis including all univariable predictors simultaneously. Firstly, a multivariable analysis including the two RV size parameters (mass and volume) was carried out, and only the RV MI was proven to independently predict cardiovascular diseases. Then, a multivariable analysis, including RV MI, RA atrial area, and LV replacement fibrosis, was conducted. In this model, RV MI and LV replacement fibrosis emerged as independent predictors of cardiovascular outcomes (RV MI: hazard ratio (HR) = 1.18; LV replacement fibrosis: HR = 6.26).

CONCLUSIONS

Our results highlight the importance of CMR in cardiovascular risk stratification.

Effects of Radiofrequency Catheter Ablation on Cardiac Reserve Using Preload Stress Echocardiography in Paroxysmal and Persistent Atrial Fibrillation

The effects of catheter ablation on exercise tolerance and quality of life in patients with atrial fibrillation (AF) have been reported. We assessed cardiac function in more detail using the leg positive pressure (LPP) technique and found that contractile reserve is particularly important in relation to exercise tolerance and prognosis. In this study, we used the LPP technique to examine changes in contractile reserve immediately after ablation and 6 months later. We prospectively enrolled patients who underwent catheter ablation for AF at 2 institutes. We performed LPP stress echocardiography 2 to 3 days after (FU-1) and 6 months after (FU-2) ablation to examine changes in cardiac function indexes. The primary end point was improvement in contractile reserve. Ultimately, 109 patients (mean age 67.4 ± 9.6 years; 70% men) underwent 2 sessions of LPP stress echocardiography. The median CHA₂DS₂-VAS_C score was 2 (interquartile range 13). From FU-1 to FU-2, the change in the stroke volume index after the LPP maneuver increased in patients with paroxysmal and persistent AF with low CHA₂DS₂-VAS_C scores (both p <0.05). Regardless of AF subtype, contractile reserve at FU-2 improved in patients with low CHA₂DS₂-VAS_C scores compared with that at FU-1. In contrast, patients with high CHA₂DS₂-VAS_C scores had no change. In conclusion, patients with AF with a low CHA₂DS₂-VAS_C score had improved contractile reserve after ablation, whereas patients with high scores did not show any improvement. Aggressive interventions in patients with high scores may lead to better management after catheter ablation.

Prevalence and prognostic significance of ischemic late gadolinium enhancement pattern in non-ischemic dilated cardiomyopathy

BACKGROUND

Typical late gadolinium enhancement (LGE) patterns in dilated cardiomyopathy (DCM) include intramyocardial and subepicardial distribution. However, the ischemic pattern of LGE (subendocardial and transmural) has also been reported in DCM without coronary artery disease (CAD), but its correlates and prognostic significance are still not known. On these bases, this study sought to describe the prevalence and prognostic significance of the ischemic LGE pattern in DCM.

METHODS

A total of 611 DCM patients with available cardiac magnetic resonance were retrospectively analyzed. A composite of all-cause-death, major ventricular arrhythmias (MVAs), heart transplantation (HTx) or ventricular assist device (VAD) implantation was the primary outcome of the study. Secondary outcomes were a composite of sudden cardiac death or MVAs and a composite of death for refractory heart failure, HTx or VAD implantation.

RESULTS

Ischemic LGE was found in 7% of DCM patients without significant CAD or history of myocardial infarction, most commonly inferior/inferolateral/anterolateral. Compared to patients with non-ischemic LGE, those with ischemic LGE had higher prevalence of hypertension and atrial fibrillation or flutter. Ischemic LGE was associated with worse long-term outcomes compared to non-ischemic LGE (36% vs 23% risk of primary outcome events at 5 years respectively, P = .006), and remained an independent predictor of primary outcome after adjustment for clinically and statistically significant variables (adjusted hazard ratio 2.059 [1.055-4.015], P = .034 with respect to non-ischemic LGE).

CONCLUSIONS

The ischemic pattern of LGE is not uncommon among DCM patients without CAD and is independently associated with worse long-term outcomes.

Hyperemic myocardial blood flow in patients with atrial fibrillation before and after catheter ablation: A dynamic stress CT perfusion study

BACKGROUND

Atrial fibrillation (AF) patients without coronary artery stenosis often show clinical evidence of ischemia. However myocardial perfusion in AF patients has been poorly studied. The purposes of this study were to investigate altered hyperemic myocardial blood flow (MBF) in patients with AF compared with risk-matched controls in sinus rhythm (SR), and to evaluate hyperemic MBF before and after catheter ablation using dynamic CT perfusion.

METHODS

Hyperemic MBF was quantified in 87 patients with AF (44 paroxysmal, 43 persistent) scheduled for catheter ablation using dynamic CT perfusion, and compared with hyperemic MBF in 87 risk-matched controls in SR. Follow-up CT after ablation was performed in 49 AF patients.

RESULTS

Prior to ablation, hyperemic MBF of patients in AF during the CT (1.29 ± 0.34 ml/mg/min) was significantly lower than in patients in SR (1.49 ± 0.26 ml/g/min, p = 0.002) or matched controls (1.65 ± 0.32 ml/g/min, p < 0.001); no significant difference was seen between patients in SR during the CT and matched controls (vs. 1.50 ± 0.31 ml/g/min, p = 0.815). In patients in AF during the pre-ablation CT (n = 24), hyperemic MBF significantly increased after ablation from 1.30 ± 0.35 to 1.53 ± 0.17 ml/g/min (p = 0.004); whereas in patients in SR during the pre-ablation CT (n = 25), hyperemic MBF did not change significantly after ablation (from 1.46 ± 0.26 to 1.49 ± 0.27 ml/g/min, p = 0.499).

CONCLUSION

In the current study using stress perfusion CT, hyperemic MBF in patients with AF during pre-ablation CT was significantly lower than that in risk-matched controls, and improved significantly after restoration of SR by catheter ablation, indicating that MBF abnormalities in AF patients are caused primarily by AF itself.

Clinical utility of cardiac magnetic resonance imaging to assess the left atrium before catheter ablation for atrial fibrillation - A systematic review and meta-analysis

AIMS

This systematic review and meta-analysis aims to clarify the role of pre-procedural cardiac magnetic resonance imaging (MRI) in identifying the association between left atrial (LA) characteristics and post-ablation atrial fibrillation (AF) recurrence. These characteristics include LA fibrosis, emptying function, sphericity, volume, volume index, peak strain and post-contrast T1 relaxation time.

METHODS

PubMed, EMBASE, and Cochrane were searched up to July 2020 for English language articles reporting the use of cardiac MRI in catheter ablation for AF. Studies reporting the prognostic value of pre-ablation cardiac MRI were included. All references and citations were filtered for relevant manuscripts.

RESULTS

Twenty-four publications were identified. Every 10% increase in LA fibrosis was associated with a 1.54-fold increase in post-ablation AF recurrence (95%CI: 1.39-1.70, I² = 50.1%). Every 10 ml increase in LA volume resulted in a hazard ratio of 1.07 (95%CI:1.03-1.12; I² = 41.4%) for post-ablation AF recurrence. For LA sphericity, there was no significant association with post-ablation AF recurrence (HR: 1.032 [95%CI: 0.962-1.103, I² = 49.6%). Egger's test was non-significant for publication bias in all meta-analyses. LA volume index, emptying function, peak strain and post-contrast LA T1 relaxation time had insufficient compatible publications to conduct a meta-analysis.

CONCLUSION

LA fibrosis quantified by cardiac MRI is associated with risk of AF recurrence after AF ablation, while increased LA volume is associated with AF recurrence to a lesser extent. There remains insufficient evidence to support the routine measurement of LA sphericity, LA volume index, LA emptying function, peak strain and LA T1 relaxation time to predict AF recurrence after AF ablation.

Left ventricular fibrosis by extracellular volume fraction and the risk of atrial fibrillation recurrence after catheter ablation

Background

Left ventricular (LV) extracellular volume fraction (ECV) provides prognostic information in patients with variety of cardiomyopathies. However, data on the clinical significance of LV ECV in patients with atrial fibrillation (AF), especially in patients without replacement fibrosis are sparse. This study sought to investigate whether the presence of LV fibrosis identified by cardiac magnetic resonance (CMR) ECV quantification would independently predict the recurrence of AF after first catheter ablation (CA) in patients with AF.

Methods

A total of 130 consecutive patients who were referred for CA of AF underwent CMR examination prior to ablation. LV function, T1 mapping derived LV ECV, LV late gadolinium enhancement (LGE) were assessed. Patients were followed for arrhythmia recurrence after the CA procedure.

Results

Of 130 AF patients, 65 patients had paroxysmal AF, and 65 patients had persistent AF. There were 50 AF recurrences over a median follow-up period of 13 months. LV ECV were significantly higher in patients with recurrent AF compared to those with no recurrence (30.4%±3.3% vs. 27.4%±2.9%, P<0.001). In multivariable model, gender (HR: 0.348, 95% CI: 0.174-0.697, P=0.003), body mass index (BMI) (HR: 1.159, 95% CI: 1.050-1.279, P=0.003), AF duration (HR: 1.006, 95% CI: 1.001-1.011, P=0.017), and LV ECV (HR: 1.158, 95% CI: 1.071-1.251, P=0.000) were significantly associated with AF recurrence. In subgroup of patients without LGE, gender, BMI, AF duration and LV ECV were still the independent predictors of AF recurrence.

Conclusions

LV ECV expansion is associated with AF recurrence after CA and is a strong independent predictor of AF recurrence.

Left ventricular extracellular volume expansion does not predict recurrence of atrial fibrillation following catheter ablation

INTRODUCTION

A recent study reported that diffuse left ventricular (LV) fibrosis is a predictor of atrial fibrillation (AF) recurrence following catheter ablation, by measuring postcontrast cardiac T1 (an error prone metric as per the 2017 Society for Cardiovascular Magnetic Resonance consensus statement) using an inversion-recovery pulse sequence (an error prone method in arrhythmia) in AF ablation candidates. The purpose of this study was to verify the prior study, by measuring extracellular volume (ECV) fraction (an accurate metric) using a saturation-recovery pulse sequence (accurate method in arrhythmia).

METHODS AND RESULTS

This study examined 100 AF patients (mean age = 62 ± 11 years, 69 males and 31 females, 67 paroxysmal [pAF] and 33 persistent [peAF]) who underwent a preablation cardiovascular magnetic resonance (CMR) exam. LV ECV and left atrial (LA) and LV functional parameters were quantified using standard analysis methods. During an average follow-up period of 457 ± 261 days with 4 ± 3 rhythm checks per patient, 72 patients maintained sinus rhythm. Between those who maintained sinus rhythm (n = 72) and those who reverted to AF (n = 28), the only clinical characteristic that was significantly different was age (60 ± 12 years vs 66 ± 9 years); for CMR metrics, neither mean LV ECV (25.1 ± 3.3% vs 24.7 ± 3.7%), native LV T1 (1093.8 ± 73.5 ms vs 1070.2 ± 115.9 ms), left ventricular ejection fraction (54.1 ± 11.2% vs 55.7 ± 7.1%), nor LA end diastolic volume/body surface area (42.4 ± 14.8 mL/m2 vs 43.4 ± 19.6 mL/m2 ) were significantly different (P ≥ .23). According to Cox regression tests, none of the clinical and imaging variables predict AF recurrence.

CONCLUSION

Neither LV ECV nor other CMR metrics predict recurrence of AF following catheter ablation.

Use of Cardiac Computed Tomography and Magnetic Resonance Imaging in Case Management of Atrial Fibrillation with Catheter Ablation

Atrial fibrillation (AF) is the most common arrhythmia associated with the risk of morbidity and mortality in clinical patients. AF is considered as an arrhythmia type that develops and progresses through close connection with cardiac structural arrhythmogenic substrates. Since the introduction of catheter ablation-mediated electrical isolation of arrhythmogenic substrates, cardiac imaging indicates improved treatment outcome and prognosis with appropriate candidate selection, ablation catheter guidance, and post-ablation follow-up. Currently, cardiac computed tomography (CCT) and cardiovascular magnetic resonance (CMR) imaging are essential in the case management of AF at both pre-and post-procedural stages of catheter ablation. In this review, we discuss the roles and technical considerations of CCT and CMR imaging in the management of patients with AF undergoing catheter ablation.

Do most patients with obesity or type 2 diabetes, and atrial fibrillation, also have undiagnosed heart failure? A critical conceptual framework for understanding mechanisms and improving diagnosis and treatment

Obesity and diabetes can lead to heart failure with preserved ejection fraction (HFpEF), potentially because they both cause expansion and inflammation of epicardial adipose tissue and thus lead to microvascular dysfunction and fibrosis of the underlying left ventricle. The same process also causes an atrial myopathy, which is clinically evident as atrial fibrillation (AF); thus, AF may be the first manifestation of HFpEF. Many patients with apparently isolated AF have latent HFpEF or subsequently develop HFpEF. Most patients with obesity or diabetes who have AF and exercise intolerance have increased left atrial pressures at rest or during exercise, even in the absence of diagnosed HFpEF. Among patients with AF, those who also have latent HFpEF have increased risk for systemic thromboembolism and death. The identification of HFpEF in patients with obesity or diabetes alters the risk-to-benefit relationship of commonly prescribed treatments. Bariatric surgery and statins can ameliorate AF and reduce the risk for HFpEF. Conversely, antihyperglycaemic drugs that promote adipogenesis or cause sodium retention (insulin and thiazolidinediones) may increase the risk for heart failure in patients with an underlying ventricular myopathy. Patients with obesity and diabetes who undergo catheter ablation for AF are at increased risk for AF recurrence and for post-ablation increases in pulmonary venous pressures and worsening heart failure, especially if HFpEF coexists. Therefore, AF may be the earliest indicator of HFpEF in patients with obesity or type 2 diabetes, and recognition of HFpEF alters the management of these patients.

Atrial Fibrosis by Late Gadolinium Enhancement Magnetic Resonance Imaging and Catheter Ablation of Atrial Fibrillation: 5-Year Follow-Up Data

Background

Late gadolinium enhancement magnetic resonance imaging is an effective tool for assessment of atrial fibrosis. The degree of left atrial fibrosis is a good predictor of atrial fibrillation (AF) ablation success at 1 year, but the association between left atrial fibrosis and long‐term ablation success has not been studied.

Methods and Results

Late gadolinium enhancement magnetic resonance images of sufficient quality to quantify atrial fibrosis were obtained before the first AF ablation in 308 consecutive patients. Left atrial fibrosis was classified in 4 Utah stages (I, 0–10%; II, 10–20%; III, 20–30%; and IV, >30%). Patients were followed up for up to 5 years until the time of first arrhythmia recurrence or second ablation. A total of 308 patients were included; the mean age was 64.5±12.1 years, and 63.4% were men. During follow‐up, 157 patients experienced an arrhythmia recurrence and 106 patients underwent a repeated ablation. A graded effect was observed in which patients with more advanced atrial fibrosis were more likely to experience recurrent AF (hazard ratio for stage IV versus stage I, 2.73; 95% confidence interval, 1.57–4.75) and undergo a repeated ablation (proportional odds ratio for stage IV versus stage I, 5.19; 95% confidence interval, 2.12–12.69).

Conclusions

The degree of left atrial fibrosis predicts the success of AF ablation at up to 5 years follow‐up. In patients with advanced atrial fibrosis, AF ablation is associated with a high procedural failure rate.

Prognostic Significance of Left Ventricular Fibrosis Assessed by T1 Mapping in Patients with Atrial Fibrillation and Heart Failure

This study sought to investigate whether left ventricular (LV) fibrosis quantified by T1 mapping can be used as a biomarker to predict outcome in patients with atrial fibrillation (AF) and heart failure (HF). 108 patients with AF and HF were included in this study. They underwent cardiac magnetic resonance, including T1 mapping sequence to assess LV fibrosis between May 2014 to May 2016. Patients received catheter ablation for AF and pharmacological treatment for HF. The primary endpoint was a composite adverse outcome of cardiac death, subsequent HF or stroke, subsequent HF was the secondary endpoint. During follow up (median: 23 months, Q1-Q3: 11 to 28 months), 1 cardiac death, 12 strokes, and 42 HF episodes occurred. LV extracellular volume fraction (ECV) was predictive of composite adverse outcome and subsequent HF (all p < 0.001). In multivariable analysis, LV ECV was an independent predictor of composite adverse outcome (hazard ratio (HR): 1.258, 95% confidence interval (CI): 1.140–1.388, p < 0.001) and subsequent HF (HR: 1.223, 95% CI: 1.098–1.363, p < 0.001). LV fibrosis measured by T1 mapping indices significantly predicts composite adverse outcomes and subsequent HF in patients with AF and HF.

Association of fragmented QRS with left atrial scarring in patients with persistent atrial fibrillation undergoing radiofrequency catheter ablation

BACKGROUND

Fragmented QRS (fQRS) on 12-lead electrocardiography is a noninvasive marker of intramyocardial conduction delay due to ventricular scarring that has not previously been studied in atrial fibrillation.

OBJECTIVE

The purpose of this study was to assess the association of fQRS with left atrial (LA) scarring in patients with persistent atrial fibrillation (PsAF) undergoing first catheter ablation.

METHODS

A total of 376 patients with PsAF were enrolled. Severity of LA scarring was assessed using electroanatomic mapping. Narrow fQRS was defined by the presence of an additional R wave (R') or notching in the nadir of the S wave, or the presence of >1 R' in 2 contiguous leads corresponding to inferior, lateral, or anterior myocardial regions.

RESULTS

Both any degree (97.3% vs 63.3%) and severe (42.2% vs 6.3%) LA scarring were higher in patients with fQRS. Age and fQRS were found to be independent predictors of severe LA scarring. At multiple ventricular regions, fQRS had diagnostic accuracy of 79.8% for prediction of severe LA scarring. Nonpulmonary vein triggers were more often detected and ablated in patients with fQRS and severe LA scarring (84.4% vs 70%; P = .001). Atrial tachyarrhythmia recurrence was observed in 131 patients (34.8%) during 18.9 ± 7.7 months of follow-up, which was significantly higher in patients with fQRS (53.2% vs 16.8%). In multivariate analysis, fQRS was found to be a significant predictor of recurrence (hazard ratio 4.65; 95% interval confidence 2.91-7.42; P <.001).

CONCLUSION

The study results showed that fQRS is a simple, available, and noninvasive marker, and that fQRS at multiple ventricular regions is significantly associated with the severity of LA scarring in PsAF patients.

Catheter ablation of atrial fibrillation-A key role in heart failure therapy?

Atrial fibrillation (AF) and heart failure (HF) are epidemic cardiac diseases and are often detected in the same patient. Recent evidence suggests that this is not a mere coincidence but that the strategy of AF treatment may impact HF development. This review comprehensively summarizes current trial data on rhythm and rate control strategies in atrial fibrillation with a special focus on catheter ablation of AF in HF patients. For a long time, rate and rhythm control strategies for AF have been regarded as equal regarding long term mortality. Decision making has been based on the symptoms of patients. Current trials, however, show that the treatment strategy of AF and its effectiveness may significantly impact survival of HF patients. The benefits of rhythm control in HF patients may have been masked by side effects of antiarrhythmic drugs. If rhythm control, however, is achieved by catheter ablation, a reduction of HF related mortality can be observed. As catheter ablation of AF may reduce mortality in HF patients, AF ablation should be preferred over medical treatment in HF patients. In general, HF patients may profit most from rigorous AF treatment.

Catheter Ablation versus Thoracoscopic Surgical Ablation in Long Standing Persistent Atrial Fibrillation (CASA-AF): study protocol for a randomised controlled trial

BACKGROUND

Atrial fibrillation is the commonest arrhythmia which raises the risk of heart failure, thromboembolic stroke, morbidity and death. Pharmacological treatments of this condition are focused on heart rate control, rhythm control and reduction in risk of stroke. Selective ablation of cardiac tissues resulting in isolation of areas causing atrial fibrillation is another treatment strategy which can be delivered by two minimally invasive interventions: percutaneous catheter ablation and thoracoscopic surgical ablation. The main purpose of this trial is to compare the effectiveness and safety of these two interventions.

METHODS/DESIGN

Catheter Ablation versus Thoracoscopic Surgical Ablation in Long Standing Persistent Atrial Fibrillation (CASA-AF) is a prospective, multi-centre, randomised controlled trial within three NHS tertiary cardiovascular centres specialising in treatment of atrial fibrillation. Eligible adults (n = 120) with symptomatic, long-standing, persistent atrial fibrillation will be randomly allocated to either catheter ablation or thoracoscopic ablation in a 1:1 ratio. Pre-determined lesion sets will be delivered in each treatment arm with confirmation of appropriate conduction block. All patients will have an implantable loop recorder (ILR) inserted subcutaneously immediately following ablation to enable continuous heart rhythm monitoring for at least 12 months. The devices will be programmed to detect episodes of atrial fibrillation and atrial tachycardia ≥ 30 s in duration. The patients will be followed for 12 months, completing appropriate clinical assessments and questionnaires every 3 months. The ILR data will be wirelessly transmitted daily and evaluated every month for the duration of the follow-up. The primary endpoint in the study is freedom from atrial fibrillation and atrial tachycardia at the end of the follow-up period.

DISCUSSION

The CASA-AF Trial is a National Institute for Health Research-funded study that will provide first-class evidence on the comparative efficacy, safety and cost-effectiveness of thoracoscopic surgical ablation and conventional percutaneous catheter ablation for long-standing persistent atrial fibrillation. In addition, the results of the trial will provide information on the effects on patients' quality of life.

TRIAL REGISTRATION

ISRCTN Registry, ISRCTN18250790 . Registered on 24 April 2015.

Clinical, electrophysiological and imaging predictors of atrial fibrillation ablation outcome

INTRODUCTION

Significant technological advances for catheter ablation of atrial fibrillation (AF) have occurred over the last decade, with a consequent increase in numbers of patients referred for AF ablation worldwide. Despite this, long-term success rates, particularly in those with persistent AF, remain modest. The patient population presenting for AF ablation are heterogeneous with regard to age, type of AF and presence of associated cardiovascular disease. Improved understanding of factors predicting response to AF ablation may therefore help to improve patient selection for ablation procedures. Areas covered: This review outlines the clinical, electrophysiological and imaging predictors of response to radiofrequency ablation for AF in contemporary practice. Recently developed scoring systems incorporating these parameters are examined, as are factors identified thus far which may predict the outcome of cryoballoon ablation. Expert commentary: Traditional clinical factors associated with ablation outcomes serve as surrogates rather than direct measures of the underlying arrhythmia substrate. An improved understanding of this substrate could improve the prediction of response to radiofrequency ablation. Continued development of methods for characterising the arrhythmia substrate, including atrial cardiac magnetic resonance imaging and invasive voltage mapping, may inform patient risk assessment and help guide selection for catheter ablation on an increasingly individualistic basis.