Clinical management of electromagnetic interferences in patients with pacemakers and implantable cardioverter-defibrillators: review of the literature and focus on magnetic resonance conditional devices.

The number of cardiac implantable electronic devices (CIEDs) has greatly increased in the last 10 years. Many electronic devices used in daily activities generate electromagnetic interferences (EMIs) that can interact with CIEDs. In clinical practice, it is very important to know the potential sources of EMIs and their effect on CIEDs in order to understand how to manage or mitigate them. A very important source of EMI is magnetic resonance (MR), which is considered nowadays the diagnostic gold standard for different anatomical districts. In this review, we focused on the effects of EMI on CIEDs and on the clinical management. Moreover, we made a clarification about MR and CIEDs.In patients with CIEDs, EMIs may cause potentially serious and even life-threatening complications (inappropriate shocks, device malfunctions, inhibition of pacing in pacemaker-dependent patients) and may rarely dictate device replacement. The association of inappropriate shocks with increased mortality highlights the importance of minimizing the occurrence of EMI. Adequate advice and recommendations about the correct management of EMIs in patients with CIEDs are required to avoid all complications during hospitalization and in daily life. Furthermore, the article focused on actual management about MR and CIEDs.

Holter ECG for pacemaker/defibrillator carriers: what is its role in the era of remote monitoring?

Nowadays several diagnostic tools are available to investigate cardiovascular symptoms like palpitations, dizziness and syncope: ECG Holter (or ambulatory ECG, AECG), external and implantable event/loop recorders. Despite this technological burden, many diagnoses are still missed. In the meantime, we are facing an increasing use of implantable devices for cardiac pacing/defibrillation (CIED), which have rapidly evolved from simple pacing/shock boxes to devices including several diagnostic features. However, these functions are not adequately exploited in current clinical practice and several redundant diagnostic tests, like AECG, are still prescribed to CIED carriers, leading to an increase of costs and a delay in final diagnosis. This review is aimed at identifying the current role of AECG in CIED carriers in view of this technological improvement. First, we will briefly present the indications for AECG according to current guidelines. We will then provide a direct comparison of the different diagnostic features provided by AECG (and event/loop recorders) versus automatic diagnostic CIED to highlight the respective pros and cons. This will serve to carefully discuss these indications in view of the results of recent studies on CIED carriers, highlighting the need for proper implantation and follow-up. Eventually, we will provide useful hints to properly analyse AECG in CIED carriers, considering the different behaviours according to the implemented algorithms. We will conclude by suggesting updated indications for AECG.

Meta-analysis of randomized controlled trials evaluating left ventricular vs. biventricular pacing in heart failure: effect on all-cause mortality and hospitalizations.

AIM: Randomized controlled trials (RCTs) showed that biventricular (BiV) pacing reduces heart failure (HF) hospitalizations and mortality in patients with New York Heart Association (NYHA) class III-IV HF, left ventricular (LV) dysfunction, and wide QRS. We performed a systematic review and meta-analysis of the RCTs comparing LV-only vs. biventricular (BiV) pacing in candidates for cardiac resynchronization therapy (CRT). METHODS AND RESULTS: The systematic review selected five RCTs (out of 1888 analysed reports) with a cumulative number of 372 patients randomized to BiV pacing and 258 to LV-only pacing. The meta-analysis shows that BiV pacing is not superior to LV-only pacing and that these two pacing modalities do not differ with regard to death or heart transplantation [LV-only vs. BiV pacing odds ratio (OR) 1.24, 95% confidence interval (CI) 0.57-2.70 with the fixed effect model, OR 1.25, 95% CI 0.48-3.24 with the random effect model]. Specific data on hospitalizations were available only in two RCTs with a cumulative number of 127 patients randomized to BiV and 123 to LV-only pacing. The meta-analysis shows that BiV pacing is not superior to LV-only pacing and that these two pacing modalities do not differ with regard to this outcome (LV-only vs. BiV pacing OR 0.86, 95% CI 0.49-1.50 with the fixed effect model, OR 0.86, 95% CI 0.49-1.50 with the random effect model). CONCLUSIONS: Biventricular pacing is not superior to LV-only pacing, and these two pacing modalities appear to achieve similar efficacy in candidates for CRT for moderate to severe HF, in terms of all-cause mortality and hospitalizations during follow-up.

How to truly value implantable cardioverter-defibrillators technology: up-front cost or daily cost?

BACKGROUND: We calculated the daily cost of implantable cardioverter-defibrillators (ICDs) based on their actual longevity to prove whether the up-front cost is a reliable parameter for the ICD purchasing-process. METHODS. Longevity of single chamber (SC), double chamber (DC), and biventricular (BiV) ICDs from Medtronic (MDT), Guidant (GDT), and St. Jude Medical (SJM) was measured in all the patients implanted in years 2000, 2001, 2002 who reached device replacement within December 31, 2009. The cost of each ICD (device + lead/s) was normalized for its own longevity. Data are expressed as median (25th-75th percentile). RESULTS: A total of 123/153 patients completed the study, 70 percent being alive 8 years after implantation. MDT devices had a superior longevity compared with GDT and SJM (p < .001). Fifty-eight percent of replaced ICDs had a service life at least 1 year shorter than the manufacturers' prediction. Longer-lasting devices had a significantly lower daily cost: €4.8 (4.6-5.7) versus €6.8 (6.2-9.2) and €6.9 (6.2-7.6) for SC (p < .001); €6.9 (6.8-7.7) versus €12.6 (11.8-13.3) and €13.4 (10.3-16.1) for DC; €8.5 (8.3-10.3) versus €15.4 (15.1-15.8) and €14.6 (14.1-14.9) for BiV (p < .005). CONCLUSIONS: The true cost of ICD treatment is strictly dependent on device longevity, whereas device up-front cost is unreliable. This aspect should be valued in the technology purchasing process, and could set the basis for an outcome-based reimbursement system. Our observations may be the benchmark respectively for ICD longevity and daily ICD cost in future comparisons. Independent observations in the real-life scenario are needed to properly value newer technologic improvements.

Management of phrenic stimulation in CRT patients over the long term: still an unmet need ?

BACKGROUND: Phrenic stimulation (PS) may cause intolerable symptoms and prevent CRT delivery in 2-5% of patients. We sought to ensure effective cardiac resynchronization therapy (CRT) delivery by management of PS at the left ventricular (LV) target site. METHODS AND RESULTS: Two hundred and eleven consecutive patients received a CRT device despite PS occurrence at the LV target site at implantation, when a PS-LV difference >2V was achieved by LV stimulation programming (cathode, pacing vector). PS management strategy both at implantation and at follow-up (FU) aimed to keep the target LV implantation site. LV reverse remodeling was assessed by echocardiography before implantation and at follow-up. LV lead placement was lateral/posterolateral in all the 211 patients; 51 of 211 had detectable PS at FU, 26 of 211 (12.3%) were symptomatic. Symptoms occurred more frequently when PS-LV difference was <3V (16/16 vs 10/35, P < 0.001). Cathode and pacing vector reprogramming improved the PS-LV difference and symptoms in 14 of 23 patients. LV output as threshold +0.5V was helpful to manage PS symptoms in patients with a PS-LV ≤2V at FU. Median FU was 34.9 (16-50) months: 12 patients had tolerable PS symptoms, 76% (39/51) were objective responders at echocardiography compared to 74% (119/160) in patients without PS (P = NS). CONCLUSIONS: CRT delivery at long term is feasible despite PS at the target LV site. PS management is mandatory in about 12.3% of patients at FU, with 6.6% remaining symptomatic. Symptoms improve at FU when a PS-LV >3V is achieved. Further improvement in lead manufacturing and pacing electronics are awaited to meet this clinical need.

Long-term RV threshold behavior by automated measurements: safety is the standpoint of pacemaker longevity!

BACKGROUND: We studied long-term right ventricular (RV) pacing threshold (RVPT) behavior in patients consecutively implanted with pacemakers capable of automatic output reprogramming tracked by automatic RV threshold measurement (automatic verification of capture [AVC]). METHODS: All the patients had state-of-the art steroid-eluting bipolar pacing leads and were RV-paced by an AVC algorithm from the three American manufacturers. Follow-up occurred twice in the first year after implantation, then yearly until approaching elective replacement indicator. RESULTS: Three hundred and twenty-one patients aged 73 ± 12 years were observed for 49 ± 26 months on average. At implantation, RVPT was 0.54 ± 0.2 V at 0.4 ms at an average 774 ± 217 Ω impedance. Forty-one of the 321 patients (12.8%) had a permanent RVPT increase above 1.5 V at 0.4 ms: RVPT was between 1.6 and 2.5 V in 29 of 321 (9%) patients, whereas it was between 2.6 and 3.5 V in seven of 321 (2.2%) patients, and >3.5 V in five of 321 (1.5%) patients. No exit block occurred because of automatic RV output adjustment by AVC algorithms. No predictor of RVPT increase was found at multivariable analysis. The maximum RVPT increase occurred within 12 months from implantation in 19 of 321 (5.9%) patients, between the first and the second year in 12 of 321 (3.7%), between the second and the sixth year in eight of 321 (2.5%), and after the sixth year in two of 321 (0.6%). CONCLUSION: Despite technologic improvement in lead manufacturing, long-term increase of the RVPT occurs in about 13% of patients, possibly representing a serious safety issue in 3.7% when 2.5 V at 0.4 ms is exceeded. AVC algorithms can improve patients' safety by automatic tailoring of the pacing output to threshold fluctuations, while maximizing device longevity.