Treatment of atrial fibrillation with second-generation cryoballoon followed by contact-sensing radiofrequency catheter ablation for arrhythmia recurrences-results of a 5-year follow-up

INTRODUCTION

The aim of this study was to report the long-term follow-up results of cryoballoon (CB) ablation in patients with atrial fibrillation.

METHODS

All consecutive patients who underwent second-generation CB ablation from February 2015 to December 2017 were included in our study. In all procedures, we used a 28-mm CB placed via a single transseptal puncture guided by intracardiac ultrasound. A 20-mm octapolar intraluminal circular catheter was used for intracardiac recordings. A single 180-s freeze strategy was employed. Repeated procedures were performed with a 3D mapping system and radiofrequency catheters.

RESULTS

A total of 126 patients (69.8% male, mean age 57 ± 11 years), of which 77.0% had paroxysmal atrial fibrillation (PAF), were included in the study. After a 5-year period, 52.4% of patients were in sinus rhythm without AF recurrence, off antiarrhythmic drugs. A total of 61.9% of patients were free of AF recurrence when redo PVI procedures were performed. When accounting for redo pulmonary vein isolation and antiarrhythmic drugs, a total of 73.8% of the patients were without AF recurrence in long-term follow-up. The patients who underwent redo pulmonary vein isolation procedures had statistically significant lower rates of AF recurrence (p = 0.006). In patients with PAF, long-term success rates improved from 62.9 to 79.4% for patients who underwent the redo procedure (p = 0.020). In patients with persistent atrial fibrillation (PersAF), success rates went up from 41.4 to 55.1% for patients with single or repeated PVI procedure (p = 0.071). In the whole cohort, a total of 3 (2.4%) procedure-related major complications occurred which included persistent PNP, arterial pseudoaneurysm, and arteriovenous fistula.

CONCLUSION

Our data suggest a favorable long-term safety and efficacy profile of second-generation CB ablation. In the mixed paroxysmal and persistent population, up to 73.8% of patients remained free of AF recurrence in the 5-year follow-up, when accounting for redo procedures and AADs. Only 2.4% of patients experienced major complications of the ablation procedure, none with permanent sequelae.

MANAGEMENT OF PATIENTS WITH CARDIAC IMPLANTABLE ELECTRONIC DEVICES UNDERGOING MAGNETIC RESONANCE IMAGING - PROPOSAL FOR UNIFIED HOSPITAL PROTOCOL: CROATIAN WORKING GROUP ON ARRHYTHMIAS AND CARDIAC PACING

For many years, magnetic resonance imaging (MRI) was contraindicated in patients with cardiac implantable electronic devices (CIED). Today, there is a growing amount of evidence that MRI can be performed safely in the majority of patients with CIEDs. Firstly, there are devices considered MRI conditional by manufacturers that are available on the market and secondly, there is clear evidence that even patients with MRI non-conditional devices can also undergo MRI safely. Protocols have been developed and recommendations from different cardiac and radiologic societies have been published in recent years. However, the majority of physicians are still reluctant to refer these patients to MRI. Therefore, this document is published as a joint statement of the Croatian Working Group on Arrhythmias and Cardiac Pacing and Department of Radiology, Sestre milosrdnice University Hospital Centre to guide and ease the management of patients with CIED undergoing MRI. Also, we propose a unified protocol and checklist that could be used in Croatian hospitals.

[ATRIAL FIBRILLATION AND HEMODINAMICALY UNSTABLE WIDE QRS COMPLEX TACHYCARDIA – A case report]

Tachycardia is an arrhythmia characterized by heart rate > 100 / minute. According to the width of the QRS complex it can be divided into narrow QRS (< 120 ms) and wide QRS tachycardia (> 120 ms). Narrow QRS tachycardia is always supraventricular which means that its source is proximal to the bundle of His, while wide QRS tachycardia can be ventricular (source is in the ventricle, distal to the bundle of His) or supraventricular. The strategies for treating these two conditions are different so the correct diagnosis is prerequisite for optimal therapy. We present this case because the differential diagnosis of wide QRS tachycardia and therefore the treatment planning was particularly difficult due to concurrently present atrial fibrillation with hemodynamic compromise and an acute threat to the life of the patient.

On the Quest for the Best Freeze

Background—

The second-generation cryoballoon is effective in achieving acute pulmonary vein isolation (PVI) and favorable clinical outcome. To date, no data are available on factors affecting late PV reconnection after second-generation cryoballoon ablation.

Methods and Results—

A total of 29 consecutive patients (25 male, 86.2%; mean age 57.8±13.8 years) underwent a repeat procedure, after a mean 11.6±4.5 months (range, 3.5–19.7 months), after index ablation using the 28-mm second-generation cryoballoon. All repeat ablations were performed using a 3-dimensional electroanatomical mapping system. Among all 115 PVs, including 1 left common ostiums (LCOs), 25 (21.7%) showed a PV reconnection in 20 patients (1.25 per patient). Persistent PVI could be documented in 90 of 115 PVs (78.2%). In 9 of 29 patients (31%), all PVs were electrically isolated. In the multivariable analysis, time to PVI ( P =0.03) and failure to achieve −40°C within 60 s ( P =0.05) independently predicted late PV reconnection. At receiver-operator curve analysis, time to PVI <60 s identified the absence of PV reconduction (sensitivity, 86.7%; specificity, 86.2%; positive predictive value, 59.1%; and negative predictive value, 96.4%; area under the curve, 0.85; confidence interval, 0.73–0.97; P <0.001).

Conclusions—

The rate of late PV reconnection after second-generation cryoballoon ablation is low (1.25 PVs/patient). Faster time to isolation and achievement of −40°C within 60 s independently predict durable PVI. In addition, 60-s cut-off for time to PVI indicates persistent isolation with 96.4% negative predictive value. These parameters might guide the operator whether to perform further applications to ensure a long-lasting PVI.

Persistence of Phrenic Nerve Palsy Following 28-mm Cryoballoon Ablation: A Four-Year Single Center Experience

BACKGROUND

Phrenic nerve palsy (PNP) is the most frequently observed complication in the setting of cryoballoon (CB) ablation (Arctic Front, Medtronic Inc., Minneapolis, MN, USA). Although, usually transient, resolving before the end of the procedure, persistent PNP (not resolving before the end of procedure) can occur. Literature on persistent PNP after second generation CB ablation is relatively sparse.

METHODS

A total of 316 consecutive patients having undergone large 28-mm CB ablation as index procedure in the Heart Rhythm Management Center, UZ Brussels, Belgium, from January 2009 to December 2013 were retrospectively reviewed for the study. Of these 117 patients were treated with the first generation CB (CB1) and 199 patients with the second generation CB (CB2).

RESULTS

PNP occurred in 10% of the total population. Persistent PNP was only observed following CB2 ablation which occurred in 4.5% of the group. At a mean follow-up of 11 months, diaphragmatic contraction in persistent PNP patients resumed in 78% (7/9) of the patients. In a final follow-up at 5 and 20 months, PNP persisted in two patients, respectively. PNP during ablation in the right inferior pulmonary vein was only observed in the CB2 group. No predictors of persistency of PNP were observed.

CONCLUSION

Persistence of PNP only occurred in the CB2 group in 4.5% of patients. The majority of patients with persistent PNP were asymptomatic. In most of the patients having persistent PNP after ablation, complete phrenic nerve function resumed during follow-up (78%).

[The first case of radiofrequent ablation of ventricular tachycardia in a patient with ischemic cardiomyopathy in our country]

Ablation of ventricular tachycardia in patients with ischemic cardiomyopathy is more complicated and more difficult than ablation of most supraventricular tachycardias. Arrhythmogenic substrate is complex and its localisation is often unclear. Because of the tachycardia characteristics, more precise mapping methods often can't be utilised. Also, patients are usually seriously ill with decreased systolic function, heart failure, ischemia and various comorbidities where tachycardia induction and ablation procedure may facilitate abrupt hemodynamic disturbance. Uninducibility of the clinical tachycardia can be achieved in 65-95% of patients, but tachycardia recurs in 20-44% of patients. Serious complications were noted in 8% of patients with lethal outcome in 2.7% of patients. Decision about therapeutic strategy should be made individually according to potential risk and procedure benefit. This paper presents the first case of the successful ablation of ventricular tachycardia in a patient with ischemic cardiomyopathy in our country.

Genome-wide association study of anthropometric traits in Korcula Island, Croatia

AIM

To identify genetic variants underlying six anthropometric traits: body height, body weight, body mass index, brachial circumference, waist circumference, and hip circumference, using a genome-wide association study.

METHODS

The study was carried out in the isolated population of the island of Korcula, Croatia, with 898 adult examinees who participated in the larger DNA-based genetic epidemiological study in 2007. Anthropometric measurements followed standard internationally accepted procedures. Examinees were genotyped using HumanHap 370CNV chip by Illumina, with a genome-wide scan containing 316730 single nucleotide polymorphisms (SNP).

RESULTS

A total of 11 SNPs were associated with the investigated traits at the level of P<10(-5), with one SNP (rs7792939 in gene zinc finger protein 498, ZNF498) associated with body weight, hip circumference, and brachial circumference (P=3.59-5.73 x 10(-6)), and another one (rs157350 in gene delta-sarcoglycan, SGCD) with both brachial and hip circumference (P=3.70-6.08 x 10(-6). Variants in CRIM1, a gene regulating delivery of bone morphogenetic proteins to the cell surface, and ITGA1, involved in the regulation of mesenchymal stem cell proliferation and cartilage production, were also associated with brachial circumference (P=7.82 and 9.68 x 10(-6), respectively) and represent interesting functional candidates. Other associations involved those between genes SEZ6L2 and MAX and waist circumference, XTP6 and brachial circumference, and AMPA1/GRIA1 and height.

CONCLUSION

Although the study was underpowered for the reported associations to reach formal threshold of genome-wide significance under the assumption of independent multiple testing, the consistency of association between the 2 variants and a set of anthropometric traits makes CRIM1 and ITGA1 highly interesting for further replication and functional follow-up. Increased linkage disequilibrium between the used markers in an isolated population makes the formal significance threshold overly stringent, and changed allele frequencies in isolate population may contribute to identifying variants that would not be easily identified in large outbred populations.

Prevalence of increased body weight and hypertension in the population of Croatian mainland and Adriatic Islands--are islanders really healthier?

The aim of this study was to compare the prevalence of the hypertension and the increased body weight (BMI) between Croatian mainland and Adriatic island population. The data from the Croatian Adult Health Survey (N = 9,070) served as an estimate for the mainland Croatian population, while the data from "1001 Dalmatian study" (N = 1,001) were collected from four Adriatic islands; Rab, Vis, Lastovo and Mljet. The prevalence of increased body weight and hypertension was calculated for the four age groups and analyzed using chi-square test. The results indicate that men from the islands less frequently had normal body mass index (P < 0.001), and were more frequently overweight (P < 0.001). The prevalence of overweight and obesity were similar between the island and mainland women. The percent of normotensive respondents in men was significantly lower in islands (P < 0.001), while the prevalence of newly diagnosed hypertension was significantly higher among islanders in both genders (P < 0.001). Despite the traditionally prevalent Mediterranean diet and overall more favorable lifestyle islanders may not be as healthy as previously studies suggested, in terms of cardiovascular risk factors prevalence. This might be related to the poor access to health care and preventive measures or low interest for health care especially among men on the islands, reflected in the higher prevalence of newly diagnosed hypertension. These findings suggest that island populations represent good candidates for disease awareness programs and health promotion interventions.

Pathogenesis and management issues for non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has, although it is a very common disorder, only relatively recently gained broader interest among physicians and scientists. Fatty liver has been documented in up to 10 to 15 percent of normal individuals and 70 to 80 percent of obese individuals. Although the pathophysiology of NAFLD is still subject to intensive research, several players and mechanisms have been suggested based on the substantial evidence. Excessive hepatocyte triglyceride accumulation resulting from insulin resistance is the first step in the proposed ‘two hit’ model of the pathogenesis of NAFLD. Oxidative stress resulting from mitochondrial fatty acids oxidation, NF-κB-dependent inflammatory cytokine expression and adipocytokines are all considered to be the potential factors causing second hits which lead to hepatocyte injury, inflammation and fibrosis. Although it was initially believed that NAFLD is a completely benign disorder, histologic follow-up studies have showed that fibrosis progression occurs in about a third of patients. A small number of patients with NAFLD eventually ends up with end-stage liver disease and even hepatocellular carcinoma. Although liver biopsy is currently the only way to confirm the NAFLD diagnosis and distinguish between fatty liver alone and NASH, no guidelines or firm recommendations can still be made as for when and in whom it is necessary. Increased physical activity, gradual weight reduction and in selected cases bariatric surgery remain the mainstay of NAFLD therapy. Studies with pharmacologic agents are showing promising results, but available data are still insufficient to make specific recommendations; their use therefore remains highly individual.