Optimizing Patient Selection for Physiological Pacing in Bradyarrhythmia: Factors Associated With High Ventricular Pacing Burden

Background

Right ventricular (RV) pacing is established as the most common ventricular pacing (VP) strategy for patients with symptomatic bradyarrhythmia. Some patients with high VP burden suffer deterioration of left ventricular (LV) function, termed pacing-induced cardiomyopathy (PICM). Patients who pace > 20% of the time from the RV apex are at increased risk of PICM, but independent predictors of increased RV pacing burden have not been elucidated in those who have a permanent pacemaker (PPM) inserted for bradyarrhythmia.

Methods

We aimed to identify factors that are associated with increased VP burden > 20%, hence determining those at risk for resultant PICM. In this retrospective cohort study, we identified the most recent 300 consecutive cardiac implantable electronic device (CIED) implants in our center and collected past medical history, electrocardiogram (ECG), echo, medication and pacemaker check data.

Results

A total of 236 individuals met inclusion criteria. Of the patients, 35% had RV pacing burden < 20%, while 65% had VP burden ≥ 20%; 96.2% of patients with complete heart block (CHB) paced > 20% (P = 0.002). Utilization of DDD or VVI (75.2% and 89.2% of patients, respectively) without mode switch algorithms was associated with VP > 20% (P < 0.001). Male or previous coronary artery bypass grafting (CABG) patients also statistically paced > 20%. Other factors trending towards significance included prolonged PR interval, atrial fibrillation or more advanced age.

Conclusion

High-grade atrioventricular (AV) block was associated with an RV pacing burden > 20% over 3 years but this was not consistent in patients with only transient episodes of high-grade AV block. We found a significant association between high VP% and male sex, previous CABG and the absence of mode switching algorithms.

Left bundle branch area pacing as a first line pacing strategy, which patients should we consider?

Background

A higher right ventricular (RV) pacing burden in those with permanent pacemakers results in accelerated pacing induced cardiomyopathy, in addition to increased incidence of heart failure and mortality [1–3]. This process may necessitate upgrade to a biventricular system in time, as the cardiomyopathy progresses. Physiological conduction system pacing targets such as His-bundle pacing (HBP) or Left Bundle Branch Area Pacing (LBBAP) have been shown to generate comparatively narrower QRS complexes and thus mitigate this cardiomyopathy development [4,5].

The 2021 ESC guidelines have a class 2b indication for consideration of HBP as an alternative to RV pacing in those with AV block and left ventricular ejection fraction &gt;40%, who are anticipated to have &gt;20% ventricular pacing burden [6].

Purpose

To retrospectively identify ECG, echocardiographic, permanent pacemaker (PPM) setting and patient factors associated with high RV pacing burden that may aid selection of those who may benefit from conduction system pacing (CSP).

Methods

We retrospectively identified 300 consecutive patients who underwent cardiac implantable electronic device insertion in our Electrophysiology Lab from the years 2017–2018. We excluded patients who underwent generator replacements, in addition to those who had biventricular devices or implantable cardioverter defibrillators inserted. We collated ECG, echo, past medical history and pacing data for each patient over a three-year follow up period.

Data were analysed using SPSS v.26.

Results

160 patients met inclusion criteria. Those with an RV pacing burden &gt;20% were categorised group one (n=85) and those with &lt;20% in group two (n=75). Baseline characteristics of these two groups are compared in Table 1 and Table 2.

Our analysis showed that significant differences between these groups included a lower mean HR (Table 1) (55.1±17.8 vs 57.63±17.4) with a more prolonged PR interval (225.7ms ± 8.34 vs. 188.6ms ± 6.62) or atrial fibrillation/flutter (AF/AFL) on admission ECG. There were more males with a greater mean age (High Ventricular Paced (VP) = 76.6 years ± 8.4 vs Low VP = 71.23 years ± 12.3) in the higher VP group, and they demonstrated more incidence of dilated RA/RV on echo (Enlarged RA = 30.5%; Enlarged RV = 23.6% vs 10% and 8.4% respectively).

There were significant differences in PPM indications and setting between groups (Table 2), with the higher VP groups having PPM inserted for persistent high-grade AV block (CHB = 31.5% vs 4.9% and Mobitz 2 = 9.6% vs 0%) and had less MVP mode activated (Mode switch algorithm = 13.3% vs 71%).

Conclusion

Our data suggests that those with persistent high grade AV block such as Mobitz 2 or CHB should be considered for CSP. Other considerations include older age, male sex, dilated RV/RA, prolonged PR, lower intrinsic HR or AF/AFL on admission ECG. PPM mode switching settings to reduce RV pacing burden should be utilised where possible.

Funding Acknowledgement

Type of funding sources: None.

Evaluation of Effectiveness and Tolerability of Fondaparinux in the Management of Symptomatic Acute Coronary Syndrome: A Real-World Evidence-Based Study on an Indian Population

INTRODUCTION

Fondaparinux is a low molecular weight heparin anticoagulant used to manage the full spectrum of acute coronary syndrome (ACS) patients and has proved its efficacy and safety in multiple clinical trials. However, there are limited data available showing whether the same results could be reproduced in real-world practice on an Indian population. Our objective was to determine the effectiveness and tolerability of fondaparinux in the management of symptomatic ACS in real-world clinical practice.

METHODS

The EMR data of hospitalized ACS patients (n = 611), from January 2015 to January 2020, representing UA or NSTEMI or STEMI and were prescribed fondaparinux (2.5 mg once daily) to manage ACS were analyzed. The effectiveness was analyzed as recurrence of ACS and tolerability as total incidence of major bleeding during hospitalization, at 30 days and 180 days. Appropriate statistical analysis was used with a statistically significance of p value < 0.05.

RESULTS

The incidence of recurrent ACS was not seen during hospitalization and in the first 30 days, while in only 0.65% (n = 4) patients, ACS reoccurred within 180 days. In a mean duration of 172.75 ± 3.20 days, UA was reported in 0.49% (n = 3) patients, NSTEMI in 0.16% (n = 1) of patients, and STEMI was not documented. None of the major bleeding events occurred during the entire study period, whereas minor bleeding events were reported during hospitalization 0.98% (n = 6) and at 30 days 0.16% (n = 1). The bleeding events were statistically insignificant (p value > 0.05). No incidences of stent thrombosis were reported during the entire study period.

CONCLUSIONS

In the real world, fondaparinux was found to be effective and tolerable when used to manage symptomatic ACS patients regardless of revascularization procedure with no incidence of stent thrombosis, and minimal recurrent ACS and insignificant increase in bleeding events.

Genetic evaluation of reproduction performance of Jersey × Red Sindhi crossbred cows

Aim:

The present investigation was undertaken to study the reproduction performance and effect of non-genetic factors on reproduction performance of Jersey crossbred cows.

Materials and Methods:

Data on 355 Jersey crossbred cattle maintained at the Post-graduate Research Institute in Animal Sciences, Kattupakkam, Tamil Nadu, distributed over 30 years (1985 to 2014). The effect of various non-genetic factors including the period of birth, season of birth, period of calving, season of calving and parity were analyzed through least-squares analyses using univariate general linear model. The different (co)variance components for calculation of genetic parameters were estimated using restricted maximum likelihood method by fitting an animal model.

Results:

The overall least-squares means (±standard error) of age at first service, age at first calving, weight at first calving, service period, calving interval, dry period, and number of services per conception were 848.06±9.72 days, 1204±12.20 days, 289.81±1.71 kg, 210.01±6.41 days, 489.12±6.45 days, 137.96±5.58 days, 2.50±0.07, respectively. Period of calving had either significant (p<0.05) or highly significant (p<0.01) effect on all reproduction traits studied except service period, calving interval, and dry period. Number of services per conception was affected by season of calving. Parity had significant influence (p<0.05) or highly significant (p<0.01) influence on all the traits studied except service period and dry period. Heritability estimates of age at first service, age at first calving, weight at first calving, service period, calving interval, dry period, and number of services per conception were 0.299, 0.220, 0.017, 0.142, 0.222, 0.177, and 0.042, respectively. The estimates of repeatability for service period, calving interval, dry period, and number of services per conception were 0.219, 0.234, 0.420, and 0.001, respectively.

Conclusions:

The reproduction performances of Jersey × Red Sindhi crossbreds were lower when compared to the earlier reports on Jersey crossbreds. Heritability and repeatability values were also low to moderate, indicating limited scope for improvement through selection.

Isolated left ventricular non-compaction in association with ventricular tachycardia

A 32-year-old young male was found to have non-sustained, repetitive, monomorphic ventricular tachycardia of right bundle branch morphology during routine pre-anaesthetic evaluation for orthopaedic surgery. Echocardiography and left ventricular angiogram were suggestive of isolated non-compaction of left ventricular apex with systolic dysfunction. He was successfully managed with anti-arrhythmic drugs and had an uneventful 9-month follow-up. The index case is an unusual association of asymptomatic, non-sustained ventricular tachycardia with isolated ventricular non-compaction.

Effect of percutaneous transvenous mitral commissurotomy on left atrial appendage function: an immediate and 6-month follow-up transesophageal Doppler study

BACKGROUND

The left atrial appendage (LAA) is a common site of thrombus formation and is the source of systemic thromboembolism in patients with rheumatic mitral stenosis. LAA contractile dysfunction is a common finding in these patients. The aim of this study was to assess immediate and 6-month follow-up LAA function by transesophageal Doppler echocardiography in patients who underwent percutaneous transvenous mitral commissurotomy (PTMC).

METHODS

Forty-seven consecutive patients with symptomatic critical mitral stenosis who underwent PTMC were enrolled. All had underwent transthoracic and transesophageal echocardiography before, 24 hours after, and 6 months after PTMC. Pulse Doppler velocities of the LAA were measured, including peak early diastolic (E wave), peak late diastolic (A wave), and peak systolic (S wave). The corresponding tissue Doppler velocities of the LAA, including peak early diastolic (E(LAA)), peak late diastolic (A(LAA)), and peak systolic (S(LAA)), were also measured. LAA ejection fraction was measured using the modified Simpson's method.

RESULTS

The mean age of the 47 enrolled patients was 31.7 ± 10.26 years. Thirty-eight patients were in sinus rhythm, and the remaining nine were in atrial fibrillation. PTMC was successful in all patients. The pulse Doppler velocities of the LAA at baseline, after PTMC, and at 6-month follow-up were as follows: for the E wave, 15.29 ± 2.26, 17.02 ± 2.25, and 17.97 ± 2.55 cm/sec, respectively (P < .001); for the A wave 22.45 ± 4.11, 24.19 ± 4.21, and 25.99 ± 4.51 cm/sec, respectively (P < .001); and for the S wave, 28.52 ± 4.37, 31.45 ± 5.37, and 33.06 ± 4.99 cm/sec, respectively (P < .001). The corresponding tissue Doppler velocities of LAA were as follows: for E(LAA), 4.65 ± 0.91, 5.28 ± 0.85, and 5.80 ± 0.84 cm/sec, respectively (P < .001); for A(LAA), 6.67 ± 1.12, 7.33 ± 1.17, and 7.88 ± 1.22 cm/sec, respectively (P < .001); and for S(LAA), 4.67 ± 1.12, 5.52 ± 1.18, 6.07 ± 1.11 cm/sec, respectively (P < .001). There was a nonsignificant increase in LAA ejection fraction (48.97 ± 8.14% vs 52.3 ± 13.76% vs 52.11 ± 16.3%, respectively, P = .052). On subgroup analysis between patients in sinus rhythm and those with atrial fibrillation, there was no significant difference for LAA ejection fraction and pulse and tissue Doppler velocities. Very good intraclass correlation of the LAA parameters was also observed for the reproducibility of the data.

CONCLUSIONS

The present study shows contractile dysfunction of the LAA in patients with critical mitral stenosis, which significantly improved after PTMC, and a further improvement was observed at 6-month follow-up. Favorable 6-month improvements in LAA parameters suggest continuous structural remodeling of the LAA after PTMC, which is clinically attributed to the absence of thromboembolism. Although there was an improvement in LAA function, it was far below the normal range, suggesting a need for continuous long-term monitoring and management of thromboembolism in these patients.