Incidence of Coronary Artery Disease After Permanent Pacemaker Implantation: A Hospital-based Study from East India.

Bradyarrhythmias, characterized by heart rates of <60 bpm due to conduction issues, carry risks of sudden cardiac death and falls. Pacemaker implantation is a standard treatment, but the interplay between bradyarrhythmias, coronary artery disease (CAD), and patient attributes requires further exploration. This study was a retrospective hospital record-based study that analyzed data from 699 patients who underwent pacemaker implantation for symptomatic bradyarrhythmias between February 2019 and February 2022. Clinical parameters, coronary angiography (CAG) findings, ejection fraction, and indications for pacemaker implantation were documented. The relationship between CAD severity, specific bradyarrhythmias, and ejection fraction was explored. Statistical analysis included chi-squared tests and t tests. The mean age of the study population (n = 699) was 66.75 years (male:female ratio, 70:30), with 77.2% having type 2 diabetes and 61.6% being hypertensive. The majority of patients had minor or non-obstructive CAD (61.8%), followed by normal CAG findings (25.75%) and obstructive CAD (12.45%). Complete heart block (CHB) was the primary indication for pacemaker implantation (55.2%), followed by sick sinus syndrome (22.3%). The results did not show any association between ejection fraction and CAG findings. Patients who presented with CHB had a higher incidence of obstructive CAD, indicating greater severity. This study sheds light on the intricate interplay between severe bradyarrhythmias, CAD, and patient characteristics. Our analysis revealed no statistical significance between obstructive CAD and the need for a permanent pacemaker. This makes us question our practice of maintaining a low threshold for coronary angiography during pacemaker implantation. The observed low yield and anticoagulation protocol reassure us of the choice to delay this diagnostic intervention. These insights can guide tailored management strategies, enhancing clinical care approaches for patients with severe bradyarrhythmias necessitating pacemaker implantation.

Endless loop tachycardia among patients with devices having advanced preventive algorithms: A case series and brief review.

BACKGROUND: Endless loop tachycardia (ELT) is the commonest pacemaker mediated tachycardia (PMT) encountered among patients with cardiac implantable electronic devices (CIEDs). Despite being enabled with various preventive algorithms, we encountered several cases having recurrent, long, and symptomatic ELT. MATERIALS AND METHODS: We retrospectively analyzed consecutive device checkups at device clinic at a single center of eastern India between January 2019 to March 2023. RESULTS: There were 20 cases of confirmed and sustained ELT among 4520 device checks. Although mostly benign, in two cases ELT led to clinical worsening in patients having left ventricular (LV) systolic dysfunction. Even with good ventricular function, ELT resulted in improper atrioventricular (AV) synchrony leading to disabling symptom in one case. The differentiation of ELT from sinus tachycardia and atrial tachycardia (AT) was not always easy. Magnet application is certainly useful to differentiate. The situations that provoked ELT in this study were-long AV delays, VIP (ventricular intrinsic preferences)/MVP (managed ventricular pacing), atrial non-capture, atrial under/over sensing, premature ventricular contractions (PVCs)/couplets, premature atrial contractions (PAC) and slower ventriculo-atrial (VA) conduction. Rate responsive shortening of post-ventricular atrial refractory period (PVARP) also promoted its occurrence and hindered troubleshooting. When ELT occurred despite post-PVC extension of PVARP, lowering the atrial sensitivity, switching to bipolar sensing and manual setting of longer PVARP after measuring VA conduction time were useful. "Rate responsive PVARP" had to be turned off in a few cases to prevent ELT. On the contrary, an over aggressive prolongation of PVARP led to repetitive non-reentrant ventriculo-atrial synchrony (RNRVAS) in two cases. Checking VA conduction during implantation and noninvasive program stimulation (NIPS) during follow up were useful to check the tendency for ELT. CONCLUSION: Clinically significant ELT is rare but not uncommon among devices having in-built preventive algorithms. Manual adjustments are often useful to troubleshoot the same.

"On-Off" phenomenon in a case of concealed left lateral atrio-ventricular accessory pathway - What is the mechanism?

We report a case of symptomatic supraventricular tachycardia who had absent VA conduction during electrophysiology study. The interesting finding was appearance of VA conduction only at a specific cycle length of ventricular pacing which reproducibly induced a sustained orthodromic re-entrant tachycardia (ORT). We review the literature and conclude that supernormal AP conduction can explain such phenomenon.

Absent ventriculo-atrial conduction during right ventricular apical pacing but nodal response during para-Hisian pacing - What is the mechanism?

A 13-year-old-girl presented with one episode of pre-syncope while standing in a train. Her ECG was suggestive of preexcitation. Echocardiography revealed structurally normal heart without any ventricular hypertrophy. During electrophysiology study, her ventriculo-atrial (VA) conduction was absent even on isoprenaline. However, a para-Hisian pacing maneuver (PHP) revealed consistent VA conduction with a nodal response. This finding indicated that the VA dissociation at baseline was at infra-Hisian (VH) level and conduction at HA level was intact. In addition, this finding is coherent with a speculation of a fasciculo-ventricular pathway (FVP) resulting in such an ECG pattern in her. Pacing from various atrial sites (right atrium, coronary sinus) exhibited nearly fixed preexcitation and short non-varying HV interval confirmatory of FVP. Testing for a PRKAG mutation was advised for her.

Unexpected stormy course after uneventful device closure of atrial septal defect - Possibly due to post-COVID-19 inflammatory state.

COVID-19 infection has myriad manifestations from self-limiting illness to stormy multi-organ failure. A 28-year-old woman negative for COVID reverse transcription-polymerase chain reaction underwent an uneventful elective device closure of atrial septal defect on intubation anesthesia. While a brief postprocedural endotracheal bleed was noted, significant hypoxia and respiratory distress ensued after extubation with biventricular dysfunction, pleural effusion, and radiographic evidence of acute respiratory distress syndrome. COVID antibodies were positive, and inflammatory markers were elevated. After a conservative multipronged medical management including anticoagulation, antibiotics, aspirin, beta-blocker, diuretics, and sildenafil, she improved in 1 week. The clinical course during this pandemic era gives a possibility of a post-COVID inflammatory syndrome as a potential etiology.

Retrograde ventriculoatrial jump-What is the mechanism?

During ventricular extra stimuli(VES) protocol a VA jump was noted. In upper panel with VES @ 500/270 ms (Fig A) the His signal appeared after the A-EGM, ruling out pure nodal VA conduction and confirming presence of an accessory pathway (AP). The H signal was delayed due to probable retrograde RBBB. The atrium was already depolarised via AP and the VA traversing via left bundle-His-node got blocked with a H signal. In the lower panel with VES of 500/260 ms the retrograde AP conduction reached the effective refractory period and pure nodal VA conduction took place along with retrograde RBBB. The retrograde VA jump was hence due to a jump from AP to AV node.

Change in the H-V Interval Without a Change in QRS Morphology During Atrial Pacing in a Case of Wolff-Parkinson-White Syndrome-What is the Mechanism?

In the background of an accessory pathway (AP), the H-V interval can vary during atrial/coronary sinus pacing, but only with a concomitant change in the QRS morphology and the degree of pre-excitation. In an interesting case of a 62-year-old woman, the H-V interval varied during coronary sinus pacing despite a fixed pre-excitation. This appears to have happened due to infra-Hisian complete atrioventricular dissociation, which resulted from iatrogenic mechanical bumping of the left anterior fascicle in the background of right bundle branch block and left posterior hemiblock.

Inappropriate defibrillator shock due to EMI despite noise reversion and SecureSense - What is the mechanism?

Implantable cardioverter defibrillator (ICD) shocks are always a matter of anxiety and concern for both patient and clinician. We report a case of ischemic cardiomyopathy who reported to us after receiving two shocks within 48 hours. The therapy was inappropriate as noted from device logs. EMI was identified as the incriminating cause. We discuss the reasons why he received the therapy despite active 'Noise reversion' and 'SecureSense' algorithms to avoid noise /EMI related oversensing.

Positive QRS complex in limb lead 2 with negative QRS in lead 3 on surface electrocardiogram: A novel predictor for anterior location of right-sided accessory pathways (10-1 o'clock on tricuspid annulus).

BACKGROUND: Localization of atrioventricular accessory pathways (AP) from Electrocardiogram (ECG) is crucial for successful ablation. We analyzed the value of limb lead 2 versus 3 QRS vector discordance on surface ECG among right-sided pathways. METHODS: Data from consecutive patients undergoing successful ablation of manifest AP were analyzed. They were categorized into two groups-Gr I: Endocardial ablation from anterior and anterolateral tricuspid annulus (TA, 10-1 o'clock, right anterolateral [RAL]); Gr II: Ablation outside this region (1-10 o'clock of TA). Inferior lead discordance (ILD) was defined as positive QRS complex (monophasic R, Rs) in lead 2 with negative/equiphasic QRS vector in lead 3 (rS, S, RS). Maximally pre-excited ECGs during electrophysiology study were compared for presence of ILD. RESULT: Among total 22 cases (Age 36 ± 18 years, 12 males), ILD was noted in 4/4 cases of Gr I. It was absent among 17/18 cases of right-sided AP in Gr II. The only case in Gr II having ILD was ablated near 8 o'clock (posterolateral). In contrast to the other four cases, aVF was negative, along with lead 3. A close differential was mid-septal AP (MSAP). However, the MSAP had absence of r in V1 and lead 2 having rS/RS complex in contrast to strongly positive QRS in RAL pathways. The sensitivity and specificity of ILD for RAL are 100% and 95%, respectively. The positive, negative predictive value, and accuracy are 80%, 100%, and 95%, respectively. CONCLUSION: Positive QRS complex in lead 2 with negative QRS in lead 3 in maximally pre-excited ECG is often predictive of anterior and anterolateral location among right-sided pathways.

Unmasking of infra-Hisian conduction abnormality by intravenous isoproterenol during electrophysiology study for syncope.

Recurrent unexplained syncope in the background of bundle branch block (BBB) often requires a pacemaker. But the decision-making for pacemaker is difficult in case of single episode of syncope with intermittent bundle branch block. We encountered one such case with intermittent LBBB, where the results of invasive EP study were even normal, until intravenous isoproterenol unmasked the infra-Hisian disease during decremental atrial pacing.

Change in VA interval by a single atrial premature depolarization - What is the mechanism?

A long VA tachycardia during a typical atrioventricular nodal reentrant tachycardia (AVNRT) can be a concomitant atypical AVNRT, atrial tachycardia or rarely atrio-ventricular reentrant tachycardia (AVRT). There are reported associations of AVNRT with other tachycardia substrates. Maneuvers are useful for differentiating the mechanism of the second tachycardia. Atrial tachycardia (AT) is one common association. When the AT originates from the lower triangle of Koch/near coronary sinus ostium, it can mimic slow-slow/fast-slow AVNRT. We encountered an interesting case where a longer VA tachycardia got reproducibly induced when a critically timed atrial premature depolarisation was delivered on typical AVNRT. It was proved to be an AT. A slow pathway modification in the lower TOK was successful to eliminate both the tachycardia substrate.

Inhibition of ventricular output in a dual chamber pacemaker with normal pacing and sensing parameters: What is the mechanism?

A 65-year-old gentleman with dual chamber pacemaker presented with presyncope. The ECG raised concerns of oversensing which was confirmed by magnet response. The device interrogation revealed noise in ventricular channel temporally associated with P wave. The pacing thresholds were normal. Although the ventricular lead impedance was within normal limit the impedance trend suggested 100 Ω decline over last 1 year. RV lead insulation failure was speculated and supported by the bipolar and unipolar intracardiac electrogram. Device was programmed to DOO temporarily. He underwent RV lead replacement uneventfully.