Cardiac injury before and after COVID-19. A longitudinal MRI study

Background

Recent MRI-based studies have raised great concern about frequent cardiac involvement even in mild or asymptomatic COVID-19. However, while signs of myocardial injury were found in large proportions of patients after COVID-19, all studies published to date lack baseline imaging and are therefore unable to discriminate between pre-existing and COVID-19-induced injury.

Purpose

In this longitudinal study, we aimed to assess the true cardiac impact of COVID-19 based on pre- and post-COVID-19 late gadolinium enhancement (LGE)-MRI.

Methods

A prospective registry of patients with serial LGE-MRIs was screened for patients with documented SARS-COV-2 infection after cardiac LGE-MRI. Eligible patients then received a post-COVID-19 LGE-MRI using the same scanner and sequence as in the pre-COVID-19 MRI. Inversion recovery prepared T1-weighted gradient echo sequences were acquired in sinus rhythm using ECG gating and a free-breathing 3D navigator, 15–20 minutes after administering an intravenous bolus of 0.2 mmol/kg of gadobutrol. A TI scout sequence was used in order to determine the optimal TI that nullified the left ventricular myocardial signal. The presence of LGE was independently assessed qualitatively by two experienced investigators blinded to patient information. For quantitative analyses a 3D-reconstruction of the left ventricle was performed using ADAS-3D software. LGE was then automatically quantified based on a prespecified signal intensity threshold of ≥3 SD above the mean of a remote non-enhanced myocardial region.

Results

Pre- and post-COVID LGE-MRI from 31 patients with cardiovascular risk factors that had recovered from mild to moderate COVID-19 (23% hospitalised) were analysed. At a median of 5 months post-COVID-19, LGE-lesions indicative of myocardial injury were encountered in 15 out of 31 patients (48%), which is in line with previous reports. However, intraindividual comparison with the pre-COVID-19 MRI reveiled all of these lesions as pre-existing and thus not COVID-19-related. Quantitative analysis detected no increase in the size of individual LGE-lesions, nor in the global left ventricular LGE-extent. There was no difference in any functional or structural parameter between pre- and post-COVID-19 MRI.

Conclusion

This longitudinal study in a cohort of patients considered at high risk of cardiac involvement, did not find any evidence for COVID-19-induced myocardial injury. The complete absence of de novo LGE lesions in this cohort is reassuring and indicates that cardiac sequelae of COVID-19 are rare and certainly not as common as previously suggested.

Funding Acknowledgement

Type of funding sources: None.

Septal flash correction with His-Purkinje pacing predicts echocardiographic response in resynchronization therapy

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Grant of the Catalan Society of Cardiology, 2019; Research Grant Josep Font 2019, Hospital Clínic de Barcelona

His-Purkinje conduction system pacing (HPCSP) has been proposed as an alternative to cardiac resynchronization therapy (CRT); however, no predictors of echocardiographic response have been described. Septal flash (SF) is a marker of intraventricular dyssynchrony.

Methods

The study aimed to analyze whether HPCSP corrects SF in patients with CRT indication, and if correction of SF predicts echocardiographic response. Prospective observational study (n=30). Left ventricular ejection fraction (LVEF) was measured with echocardiography at baseline and at 6-month follow-up. Echocardiographic response was defined as increase in 5 points LVEF. ECG Imaging was performed in 2 patients to validate ventricular activation shortening and to study the basal and HPCSP activation pattern.

Results

HPCSP shortened QRS duration by 48±21ms and SF was significantly decreased (baseline 3.6±2.2mm vs HPCSP 1.5±1.5mm p<0.0001) (Fig.1). At 6-months, mean LVEF improvement was 8.6% ± 8.7% and 64% of patients were responders. There was a significant correlation between SF correction and increased LVEF (r=0.61, p=0.004). A correction of >1.5mm had 81% sensitivity and 80% specificity to predict echocardiographic response (area under curve 0.86, p=0.019).

Conclusion

HPCSP improves intraventricular dyssynchrony and results in 64% echocardiographic responders at 6-month follow-up. Dyssynchrony improvement with SF correction may predict echocardiographic response at 6-month follow-up (Fig.2.).

129Magnetic resonance predictors of ventricular tachycardia recurrence after radiofrequency substrate ablation: septal and transmural channels

 

Ventricular tachycardia (VT) substrate-based ablation has become a gold standard in patients with structural heart disease. Success of VT ablation is related with mortality reduction.

Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) is a powerful technique to assess substrate of VT. Myocardial fibrosis is electrically inert (Core) but it is surrounded by a ‘‘border-zone (BZ)’’ where normal cardiomyocytes intermingle with dense bundles of fibrosis. Slow impulse conduction in the BZ allows for the re-entry circuits leading to VT. Both the presence and extent of LGE have been associated with VT and SCD risk. LGE-CMR tissue characterization can be depicted as pixel signal intensity (PSI) maps and can guide VT ablation.

The aim of this study was to analyze possible VT recurrence predictors in a long term follow-up of patients that underwent VT ablation (endo and/or epicardial) related with LGE-CMR PSI maps.

We analyzed 234 consecutive patients (age: 63.2 ± 14 years, follow-up: 3.14 years ±1.8) undergoing VT ablation with scar-dechannelling technique at a single center from 2013 to 2018.  110 patients underwent a preprocedural LGE-CMR, and in 94 patients (85,5%) a CMR-aided ablation using the PSI maps was performed.

All LGE-CMR images were semi-automatically processed using a dedicated software. PSI-based algorithm was applied to characterize the hyperenhanced area as core or BZ, using fixed threshold of the maximum intensity. A LV 3D shell was obtained and were imported into the navigation system. In the PSI maps, heterogenous tissue channels were defined as a continuous corridor of BZ surrounded by scar core or an anatomic barrier that connects 2 areas of healthy tissue.

Results

Overall recurrence of VT was 41.8 %. There was ICD shock reduction, from 43,6% to a 28,2% (ICD shocks before ablation 2,23 ± 7,32, after: 1,10 ± 2,92).

Left ventricle mass predicted significantly VT recurrence (Mean 168,3 ± 53,3 vs 152,3 ± 46,4 g, HR 1,02 [1,01-1,02], p < 0.001). LGE distribuition was predictive of VT recurrence when a more than 40% of the interventricular septum was involved (62,5% vs 37,8%; HR 1,6 [1,01-1,02]; p = 0,044). No differences in recurrence were found among the patterns of LGE distribution (transmural/epicardial/subendocardial or peculiar segments localizations). The amount of BZ and the total amont of Core + BZ was related with VT recurrence (BZ 26,6 ± 13,9 vs 19,56 ± 9,69 g, HR 1,03 [1,01-1,06], p = 0,012; total Core + BZ 37,1 ± 18,2 vs 29,0 ± 16,3 g, HR 1,02 [1,00-1,04], p = 0,033). Finally VT recurrence was higher in patients with channels with transmural path (66,7% vs 31,4%, HR 3,25 [1,70-6,23], p < 0,001) or midmural channels (54,3% vs 27,6%, HR 2,49 [1,21–5,13], p = 0,013).

CMR-aided scar dechanneling is a helpful and feasible technique which could identify patients with high risk of VT recurrence. High left ventricular mass, septal LGE distribution, transmural and midmural heterogeneous tissue channels were predictive factors of post ablation VT recurrence.

Abstract Figure. VTchannel & heterogeoneus tissue channel

P1163Correction of septal flash excursion with his bundle pacing

Funding Acknowledgements

Grant from the Catalan Society of Cardiology

Background

His bundle pacing (HBP) directly stimulates the conduction system and could therefore correct asynchrony and evolve as a more physiological pacing approach. Septal flash (SF) is a fast contraction and relaxation of the septum occurring during the isovolumetric contraction period. It is a specific marker of cardiac dyssynchrony.  

Purpose

Evaluate whether HBP corrects SF in patients with an indication for CRT or RV pacing.

Methods

A cohort of 20 consecutive patients undergoing HBP at our center was analyzed. HBP indications were:  Group A (n = 3): left bundle branch block (LBBB) and left ventricular (LV) dysfunction (LV ejection fraction [LVEF] < 35%); Group B (n = 14): LV dysfunction (LVEF < 50%) and atrio-ventricular block requiring permanent pacing; Group C (ablate&pace, n = 3): atrio-ventricular node ablation due to rapid atrial fibrillation.

Patients in groups B and C had a RV backup lead implanted, in line with current recommendations. The presence of SF was analyzed in 2D-echocardiography at 15 days post-implant. SF excursion was quantified using M-mode in parasternal short and long axis views as the highest amplitude of the early inward motion. Baseline SF excursion was determined during intrinsic rhythm (group A) or RV pacing (groups B and C). For each patient, the pair of measurements (baseline, HBP) in the axis with the highest baseline SF was selected.

Results

Mean LVEFs were 21 ± 8%, 32 ± 6%, and 41 ± 18% for groups A, B and C, respectively. HBP shortened QRS duration by 42 ± 15 ms and 45 ± 23 ms in groups A (Baseline QRS - HBP QRS) and B + C (RV pacing QRS - HBP QRS), respectively. At baseline, all patients except 1 had SF (Fig. 1A). The mean SF excursion was 4.3 ± 1.9 mm, with SF excursion being larger in group A than in the RV-paced groups (6.3 ± 1.5 mm vs. 3.9 ± 1.8 mm for groups A and B + C, respectively, p = 0.04). HBP abolished SF in 3 patients (15%) and, on average, decreased SF excursion by 2.3 mm (95% CI 1.3-3.2), irrespective of pacing indication (Fig. 1B). The degree of SF excursion reduction after HBP significantly correlated with QRS shortening (r = 0.53, p = 0.024) (Fig 1C).

Conclusions

In conclusion, we show that HBP results in acute correction or decrease of SF, thereby improving LBBB- or RV-induced mechanical dyssynchrony.

Abstract Figure. Septal Flash and His pacing

45Improving the optimization of cardiac resynchronization therapy: Does multipoint left ventricular pacing shorten the paced-QRS duration compared to the fusion-optimized intervals method?

Funding Acknowledgements

Cardiac Pacing Scholarship from the Spanish Society of Cardiology (SEC)

Background

Electrocardiogram-based optimization of cardiac resynchronization therapy (CRT) using the fusion-optimized intervals (FOI) method has demonstrated to improve both acute hemodynamic response and left ventricle (LV) reverse remodeling compared to nominal programming of CRT. FOI optimizes the atrioventricular (AV) and ventriculo-ventricular (VV) intervals to achieve the shortest paced-QRS duration. The recent development of multipoint pacing (MPP) enables the activation of the LV from 2 locations, also shortening the QRS duration compared to conventional biventricular pacing.

Purpose

To determine if MPP reduces the paced-QRS duration compared to FOI optimization. 

Methods

This prospective clinical study included 25 consecutive patients who successfully received a CRT with MPP pacing capability. All patients were in sinus rhythm and had an PR interval below 250 ms. The QRS duration was measured with a 12-lead digital electrocardiography (screen speed of 200 mm/s) at baseline and using 3 different configurations: MPP, FOI and a combined FOI-MPP strategy. In MPP, the intervals were (based on previous studies): 1) AV 130 ms, 2) Right ventricular (RV)-LV2 (Δ1) 5 ms, and 3) LV1-LV2 (Δ2) 5 ms. In FOI, AV and VV intervals were optimized to achieve fusion between intrinsic conduction and biventricular pacing. In FOI-MPP, the Δ2 was set at 5 ms, while AV and Δ1 intervals were optimized using the FOI method. The CRT device was programmed with the configuration that achieved a greater paced-QRS shortening. After 45 days, battery life was estimated.

Results

  Mean age was 65 ± 10 years, 20 were men (80%) and baseline QRS duration was 177 ± 17 ms. The FOI method bested nominal MPP (QRS shortened by 58 ± 16 ms vs 43 ± 16 ms, respectively, p = 0.002). Adding MPP to the narrowest QRS by FOI did not result in further shortening (FOI: 58 ± 16 ms vs FOI-MPP: 59 ± 13 ms, p = 0.81). The final configuration was FOI method alone in most cases (n = 16, 64%) and FOI-MPP in all others (n = 9, 36%; figure). In total, 10 out of 25 patients (40%) were not candidates to MPP due to: 1) pacing thresholds exceeding 3.5 V/0.4 ms at the distal or proximal electrode (8, 32%), and 2) phrenic stimulation (2, 8%). Estimated battery longevity was longer in patients receiving FOI as compared to MPP (8.3 ± 2.1 years vs. 6.2 ± 2.2 years, p = 0.04).

Conclusion

In CRT, the FOI method is not improved by coupling with MPP.  Up to 40% of patients are not candidates for MPP due to high thresholds or phrenic stimulation. The use of MPP in unselected patients would result in a decrease of battery longevity, without any additional benefit over FOI.

Abstract Figure.