Cryoablation vs. radiofrequency ablation of the atrioventricular node in patients with His-bundle pacing.

AIMS: Radiofrequency ablation (RFA) of the atrioventricular node (AVN) with His-bundle pacing (HBP) can cause rise in capture thresholds. Cryoablation (CRYO) may offer reversibility in case of threshold rise but has never been tested for AVN ablation in this setting. Our aim was to compare procedural characteristics and outcome of CRYO compared with RFA for AVN ablation in patients with HBP. METHODS AND RESULTS: Forty-four patients with HBP underwent AVN ablation for an 'ablate and pace' indication. Cryoablation was performed in the first 22 patients and RFA in the following 22 patients. Procedural characteristics, success rates, and change in His capture thresholds were compared between groups. Distance from the ablation site to the His lead was measured using biplane fluoroscopy. Acute success was 100% with both strategies. Median procedural duration was significantly longer for CRYO {50 [interquartile range (IQR) 38-63] min} compared with RFA [36 (IQR, 30-41) min; P = 0.027]. An acute threshold rise of ≥1 V was observed in four CRYO (one complete loss of capture) and three RFA patients (P = 0.38), with all of the applications being within 6 mm of the His lead tip. During follow-up, nine patients had AVN re-conduction (six CRYO vs. three RFA; P = 0.58), but only four patients required a redo procedure (all CRYO; P = 0.09). CONCLUSION: Cryoablation does not offer any advantage over RFA for AVN ablation in patients with HBP and tended to require more redo procedures. If possible, a distance of ≥6 mm should be maintained from the His lead tip to avoid a rise in capture thresholds.

Correlation between septal midwall late gadolinium enhancement on CMR and conduction delay on ECG in patients with nonischemic dilated cardiomyopathy.

BACKGROUND: Septal midwall late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) is a characteristic finding in nonischemic dilated cardiomyopathy (DCM) and is associated with adverse cardiac events. QRS-prolongation in DCM is also frequently present and a predictor of arrhythmic events and mortality. Since the His-Purkinje fibres are located in the interventricular septum, QRS-prolongation may directly result from septal fibrosis, visualized by LGE. Our aim was to study the correlation of the presence and extent of septal midwall LGE and QRS-duration. METHODS: DCM-patients with left ventricular (LV) dysfunction (LVEF < 50%) were included. LV volumes, systolic function and nonischemic septal midwall LGE, defined as patchy or stripe-like LGE in the septal segments, were quantified. QRS-duration on standard 12-lead ECG was measured. RESULTS: 165 DCM-patients were included (62% male, mean age 59 ± 15 years) with a median LVEF of 36% [24-44]. Fifty-one patients (31%) demonstrated septal midwall LGE with a median extent of 8.1 gram [4.3-16.8]. Patients with midwall LGE had increased LV end-diastolic volumes (EDV) 248 mL [193-301] vs. 193 mL [160-239], p < 0.001) and lower LVEF (26% [18-35] vs. 40% [32-45], p < 0.001). Median QRS-duration was 110 ms [95-146] without a correlation to the presence nor extent of midwall LGE. QRS-duration was moderately correlated with LV-dilation and mass (respectively r = 0.35, p < 0.001 and r = 0.30, p < 0.001). CONCLUSION: In DCM-patients, QRS-prolongation and septal midwall LGE are frequently present and often co-exist. However, they are not correlated. This suggests that the assessment of LGE-CMR has complementary value to ECG evaluation in the clinical assessment and risk stratification of DCM-patients.

Myocardial adaptation after surgical therapy differs for aortic valve stenosis and hypertrophic obstructive cardiomyopathy.

Surgical therapies in aortic valve stenosis (AVS) and hypertrophic obstructive cardiomyopathy (HOCM) aim to relief intraventricular pressure overload and improve clinical outcome. It is currently unknown to what extent myocardial adaptation concurs with restoration of intraventricular pressures, and whether this is similar in both patient groups. The aim of this study was to investigate changes in myocardial adaptation after surgical therapies for AVS and HOCM. Ten AVS and ten HOCM patients were enrolled and underwent cardiac magnetic resonance cine imaging and myocardial tagging prior to, and 4 months after aortic valve replacement (AVR) and septal myectomy, respectively. Global left ventricular (LV) analyses were derived from cine images. Circumferential strain was assessed from myocardial tagging images at the septal and lateral wall of the mid ventricle. Pressure gradients significantly decreased in both AVS and HOCM after surgery (p < 0.01), with a concomitant decrease in left atrial volume (p < 0.05) suggesting lower diastolic filling pressures. Also, LV volumes, mass and septal wall thickness decreased in both, but to a larger extent in AVS than in HOCM patients. AVR improved wall thickening (p < 0.05) and did not change systolic strain rate. Myectomy did not affect wall thickening and reduced septal systolic strain rate (p = 0.03). Both AVR and myectomy induced positive structural remodeling in line with a reduction of pressure overload. A concomitant recovery in systolic function however was found in AVR only. The systolic functional deterioration in HOCM patients seems to be inherent to myectomy and the ongoing and irreversible disease.

Long-Term Prognostic Implications of Previous Silent Myocardial Infarction in Patients Presenting With Acute Myocardial Infarction.

OBJECTIVES: This study investigated the prevalence of silent myocardial infarction (MI) in patients presenting with first acute myocardial infarction (AMI), and its relation with mortality and major adverse cardiovascular events (MACE) at long-term follow-up. BACKGROUND: Up to 54% of MI occurs without apparent symptoms. The prevalence and long-term prognostic implications of previous silent MI in patients presenting with seemingly first AMI are unclear. METHODS: A 2-center observational longitudinal study was performed in 392 patients presenting with first AMI between 2003 and 2013, who underwent late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) examination within 14 days post-AMI. Silent MI was assessed on LGE-CMR images by identifying regions of hyperenhancement with an ischemic distribution pattern in other territories than the AMI. Mortality and MACE (all-cause death, reinfarction, coronary artery bypass grafting, and ischemic stroke) were assessed at 6.8 ± 2.9 years follow-up. RESULTS: Thirty-two patients (8.2%) showed silent MI on LGE-CMR. Compared with patients without silent MI, mortality risk was higher in patients with silent MI (hazard ratio: 3.87; 95% confidence interval: 1.21 to 12.38; p = 0.023), as was risk of MACE (hazard ratio: 3.10; 95% confidence interval: 1.22 to 7.86; p = 0.017), both independent from clinical and infarction-related characteristics. CONCLUSIONS: Silent MI occurred in 8.2% of patients presenting with first AMI and was independently related to poorer long-term clinical outcome, with a more than 3-fold risk of mortality and MACE. Silent MI holds prognostic value over important traditional prognosticators in the setting of AMI, indicating that these patients represent a high-risk subgroup warranting clinical awareness.