Potential pro-arrhythmic effect of cardiac resynchronization therapy

A decline in mortality due to pump failure has been clearly documented after cardiac resynchronization therapy [CRT], however the impact on sudden cardiac death and the development of malignant ventricular arrhythmias remains questionable. Our study aims to investigate this alleged pro-arrhythmic effect of CRT using surface electrocardiogram [ECG] markers of pro-arrhythmia. Seventy five patients, who received CRT were included in this study. Manual measurement of corrected QT interval [QTc], T[peak-end] T[p-e] interval, QT dispersion [QTd] and T[peak-end] dispersion during baseline 12 lead surface ECG and after applying atrial-biventricular pacing were done. Arrhythmias post CRT was recorded from ECG, 24 h holter monitoring or pacemaker programmer event recorder. QTc interval showed significant prolongation after CRT [498.9 +/- 50.8 vs. 476.2 +/- 41.6 msec, P = 0.0001]. Comparing patients with major arrhythmogenic events [MAE] and increased frequency of premature ventricular contractions [PVCs] post CRT pacing to those patients without arrhythmias, there was a significant prolongation of the QTc interval [527 +/- 63.29 vs. 496.95 +/- 45.2 msec, P = 0.043] and T p-e interval [94.16 +/- 9 vs. 87.41 +/- 16.37 msec, P = 0.049]. While in the arrhythmogenic group, there was an insignificant decrease in QTd and T[peak-end] dispersion. QTc and T[p-e] intervals are a potential predictor of occurrence of MAE and PVCs. On the other hand, T[p-e] dispersion and QTd did not show a predictive potential for arrhythmia

Prevalence and outcome of bacterial endocarditis in patients with implantable cardiac devices infections

Cardiac device infection [CDI] is a devastating complication of permanent pacemakers [PPM] or implantable cardioverter-defibrillators [lCD]. The incidence and outcome of endocarditis among patients [Pts] with CDI is not well defined. Is to report the experience in the prevalence, clinical presentations and management of bacterial endocarditis [BE] among patients with CDI in a tertiary care cardiac center over 25 years. A total of 2630 cardiac devices implanted in a cohort of 2367 patients [pts] over 25 years were studied. Out of these, 117 [4.4%] Pts presented with CDI. Clinical, bacteriologic and both transthoracic [TTE] and transoesophageal Echocardiographic [TEE] assessments were done. Of the 117 Pts with CDI [90 males, age ranging 18-82 yrs, mean=63 +/- 6 ys], 87 [74%] had redo procedures [battery replacement in 50, repositioning of leads in 12, device extrusion in 15 or evacuation of significant haematoma in 10 pts]. Of these 87 pts, 65 had re-implants on the same day of explantation. In 30 pts [26%] no apparent cause of P1 was identified. Out of the 117 Pts with CDI, 30 pts [26% of CDI and 1.1% of total procedures] had device-related BE with vegetations appeared in all pts by TEE [15 DDD, 9 VVI, 3 CRT and 3 lCD]. The clinical presentations were prolonged fever in 25 pts [83%], significant pulmonary hypertension with thrombo-embolism in 3 pts [10%], severe sepsis and multi-organ failure in 2 pts [6%]. Twenty-eight pts [93%] had positive blood cultures Istaph.aureus in 23 [77%] and enterococci in 5]. There were only 2 Pt with negative blood cultures. Device lead vegetations were evident in 20 pts [>10mm diameter in 13 pts]. Ten pts presented with only right heart valves vegetations. Out of the 30 BE pts, 28 [93%] had P1 while 2 pts had no apparent cause but frequent intravenous injections [one drug addict and one on regular haemodialysis]. Out of the 20 pts with lead endocarditis 15 had their leads removed surgically with re-implantation of either epicardial [6 pts] or endocardial leads [9 pts]. Fifteen pts had only medical treatment with proper antibiotics [5 pts with lead BE and all 10 pts with valvular BE]. Four pts [13%] died; all had their devices implanted on same day of explanation. Conclusion: Cardiac devices Redo procedures are major risk factors for CDI specially re-implantation on same day. Device related BE carries a serious morbidity and mortality yet surgical removal of the whole system is the management of choice. Blood stream bactraemia is a potential risk factor in patients with cardiac devices and warrant prophylaxis against BE