Robert G. Hauser

Natural History and Expansive Clinical Profile of Stress (Tako-Tsubo) Cardiomyopathy

OBJECTIVES This study was designed to define more completely the clinical spectrum and consequences of stress cardiomyopathy (SC) beyond the acute event. BACKGROUND Stress cardiomyopathy is a recently recognized condition characterized by transient cardiac dysfunction with ventricular ballooning. METHODS Clinical profile and outcome were prospectively assessed in 136 consecutive SC patients. RESULTS Patients were predominantly women (n = 130; 96%), but 6 were men (4%). Ages were 32 to 94 years (mean age 68 +/- 13 years); 13 (10%) were <or=50 years of age. In 121 patients (89%), SC was precipitated by intensely stressful emotional (n = 64) or physical (n = 57) events, including 22 associated with sympathomimetic drugs or medical/surgical procedures; 15 other patients (11%) had no evident stress trigger. Twenty-five patients (18%) were taking beta-blockers at the time of SC events. Three diverse ventricular contraction patterns were defined by cardiovascular magnetic resonance (CMR) imaging, usually with rapid return to normal systolic function, although delayed >2 months in 5%. Right and/or left ventricular thrombi were identified in 5 patients (predominantly by CMR imaging), including 2 with embolic events. Three patients (2%) died in-hospital and 116 (85%) have survived, including 5% with nonfatal recurrent SC events. All-cause mortality during follow-up exceeded a matched general population (p = 0.016) with most deaths occurring in the first year. CONCLUSIONS In this large SC cohort, the clinical spectrum was heterogeneous with about one-third either male, <or=50 years of age, without a stress trigger, or with in-hospital death, nonfatal recurrence, embolic stroke, or delayed normalization of ejection fraction. Beta-blocking drugs were not absolutely protective and SC was a marker for increased noncardiac mortality. These data support expanded management and surveillance strategies including CMR imaging and consideration for anticoagulation.

Quantitative analysis of the high-frequency components of the terminal portion of the body surface QRS in normal subjects and in patients with ventricular tachycardia.

Quantitative analysis of the high-frequency components of the terminal portion of the surface QRS was performed in 42 normal subjects (group 1, ages 18–67 years, mean + SEM 34.7 + 2.2 years) and in 12 patients with symptomatic, sustained ventricular tachycardia (VT) (group 2, ages 48–76 years, mean 59 + 2.3 years). Signal averaging and high-pass, bidirectional digital filtering were used for analysis. The total duration of the QRS, the duration of the low-amplitude signals (< 40 1xV) in the terminal portion of the QRS and the amplitude of the signals in the last 40 and 50 msec of the QRS were measured at filter settings of 25 and 40 Hz. Reproducibility of the measurements was tested in 15 normal subjects by comparing results obtained from two consecutive recordings. Significant differences were found between normal subjects and VT patients for all four indexes at both 25- and 40-Hz filters. Specific values for each of the indexes were identified at the 40-Hz filtering, which could separate normal subjects from VT patients (20,uV for the amplitude of last 40 msec; 30;xV for the amplitude of last 50 msec; 120 msec for the total duration; and 39 msec for the low-amplitude signal of the filtered QRS). Using these values for the four indexes, respectively, 90%, 98%, 100% and 90% of the normal subjects and 83%, 83%, 58% and 83% for the VT group were correctly classified. The results show that the high-frequency analysis of the signalaveraged body surface QRS is a reliable, reproducible, noninvasive method for distinguishing patients with VT from normal subjects.

Deaths and cardiovascular injuries due to device-assisted implantable cardioverter–defibrillator and pacemaker lead extraction

Aims An estimated 10 000–15 000 pacemaker and implantable cardioverter–defibrillator (ICD) leads are extracted annually worldwide using specialized tools that disrupt encapsulating fibrous tissue. Additional information is needed regarding the safety of the devices that have been approved for lead extraction. The aim of this study was to determine whether complications due to device-assisted lead extraction might be more hazardous than published data suggest, and whether procedural safety precautions are effective. Methods and results We searched the US Food and Drug Administrations (FDA) Manufacturers and User Defined Experience (MAUDE) database from 1995 to 2008 using the search terms ‘lead extraction and death’ and ‘lead extraction and injury’. Additional product specific searches were performed for the terms ‘death’ and ‘injury’. Between 1995 and 2008, 57 deaths and 48 serious cardiovascular injuries associated with device-assisted lead extraction were reported to the FDA. Owing to underreporting, the FDA database does not contain all adverse events that occurred during this period. Of the 105 events, 27 deaths and 13 injuries occurred in 2007–2008. During these 2 years, 23 deaths were linked with excimer laser or mechanical dilator sheath extractions. The majority of deaths and injuries involved ICD leads, and most were caused by lacerations of the right atrium, superior vena cava, or innominate vein. Overall, 62 patients underwent emergency surgical repair of myocardial perforations and venous lacerations and 35 (56%) survived. Conclusion These findings suggest that device-assisted lead extraction is a high-risk procedure and that serious complications including death may not be mitigated by emergency surgery. However, skilled standby cardiothoracic surgery is essential when performing pacemaker and ICD lead extractions. Although the incidence of these complications is unknown, the results of our study imply that device-assisted lead extractions should be performed by highly qualified physicians and their teams in specialized centres.

Clinical course of hypertrophiccardiomyopathy with survival to advanced age

OBJECTIVES This study was designed to clarify and resolve the clinical profile of older patients with hypertrophic cardiomyopathy (HCM). BACKGROUND Adverse consequences of HCM such as sudden death and incapacitating symptoms have been emphasized for the young and middle-aged. METHODS Long-term outcome of HCM was assessed in a community-based cohort not subject to tertiary center referral bias. RESULTS Of 312 patients, 73 (23%) achieved normal life expectancy (> or =75 years; range to 96); 44 (14%) were > or =80 years old. Most patients > or =75 years (47; 64%) experienced no or only mild limiting symptoms and lived virtually their entire lives with few HCM-related clinical consequences; 26 patients (36%) experienced severe progressive symptoms. In elderly patients with HCM, diagnosis and symptom onset were considerably delayed to 74 +/- 8 and 70 +/- 11 years, respectively. For patients > or =50 years at diagnosis, the probability of survival for 5, 10, and 15 years was 85 +/- 3%, 74 +/- 4%, and 57 +/- 6%, respectively, and did not significantly differ from a matched general population (p = 0.20). Patients > or =75 years were predominantly women, and had less marked wall thickness and more frequently showed basal outflow obstruction > or =30 mm Hg (compared with those <75 years; p < 0.01 and 0.001, respectively). CONCLUSIONS Hypertrophic cardiomyopathy is frequently well tolerated and compatible with normal life expectancy, and may remain clinically dormant for long periods of time with symptoms and initial diagnosis deferred until late in life. These observations afford a measure of reassurance to many patients with HCM, a disease for which clinical course is often unfavorable and unpredictable.

Longevity of Sprint Fidelis Implantable Cardioverter-Defibrillator Leads and Risk Factors for Failure Implications for Patient Management

Background— Sprint Fidelis (Fidelis) implantable cardioverter-defibrillator leads are prone to fractures that have caused adverse events, primarily inappropriate shocks, and a few reported deaths. More than 100 000 patients have Fidelis leads. No independent multicenter long-term performance information exists for this lead, and single-center studies suggest that certain patients are at increased risk for Fidelis failure. Our aim was to assess the longevity of Fidelis leads and to evaluate clinical variables and adverse events associated with Fidelis failure. The results were compared with like data for Quattro Secure (Quattro) implantable cardioverter-defibrillator leads implanted at our centers. Methods and Results— This 3-center study included adults ≥18 years of age who received Fidelis or Quattro leads for the prevention of sudden cardiac death. From November 2001 to January 2009,1023 Fidelis and 1668 Quattro leads were implanted and followed up. The failure rate for Fidelis leads was 2.81%/y compared with 0.43%/y for Quattro leads (P<0.0001). No deaths or injuries occurred as a result of lead failure, but 42% of fractures caused inappropriate shocks. The survival of Fidelis leads at 4 years was 87.0% (95% confidence interval, 83.6 to 90.1) compared with 98.7% (95% confidence interval, 97.9 to 99.4) for Quattro leads (P<0.0001). Multivariate predictors of Fidelis failure were younger age (hazard ratio, 0.98; 95% confidence interval, 0.96 to 0.99), female gender (hazard ratio, 0.61; 95% confidence interval, 0.40 to 1.00), and cardiac disease (P=0.041). Conclusions— Compared with Quattro leads, the survival of Fidelis leads continues to decline, and Fidelis failure is notably higher in younger patients, women, individuals with hypertrophic cardiomyopathy, and patients with arrhythmogenic right ventricular dysplasia or channelopathies. These findings have significant implications for the management of patients who have Fidelis leads, and they demonstrate the importance of weighing clinical variables in assessments of implantable cardioverter-defibrillator lead performance.

Riata implantable cardioverter-defibrillator lead failure: Analysis of explanted leads with a unique insulation defect

BACKGROUND The Riata family of implantable cardioverter-defibrillator leads (St Jude Medical, Sylmar, CA) appears prone to a unique failure mechanism whereby the conductor cables wear through the silicone insulation from inside-out and are seen outside the lead body (externalized conductors). OBJECTIVE To assess the extent of Riata lead damage associated with inside-out insulation defects and their clinical consequences. METHODS In September 2011, we searched the U.S. Food and Drug Administrations Manufacturers and User Defined Experience medical device database for reports describing Riata lead failures that had been analyzed by the manufacturer. RESULTS The Manufacturers and User Defined Experience search identified 105 leads that had inside-out insulation defects. Eight-French single-coil Riata leads accounted for a higher-than-expected proportion (25.7%) of the leads with this defect. A total of 226 insulation defects were found in the 105 leads (2.2 defects per lead), including 143 inside-out defects (1.4 defects per lead). The most common location of insulation defects was distal to the proximal coil (n = 108). Twenty-eight leads (26.7%) had inside-out insulation defects underneath the shocking coils. Of 43 leads whose cables were assessed for the integrity of the ethylene-tetrafluoroethylene cable coating, 22 (51.2%) were found to be abraded, exposing the conductor surfaces. On X-ray radiography or fluoroscopy, 7 leads were found to have externalized cables; 2 of these leads had no electrical abnormalities, while 4 exhibited noise or increased impedance. Inappropriate shocks were experienced by 31 of the 105 patients (29.5%). CONCLUSION Riata leads that have inside-out insulation defects often have multiple defects, including additional inside-out abrasions along the body of the lead and beneath the shocking coils. Eight-French single-coil Riata models may be more prone to externalized cables than are dual-coil and 7-F designs. Externalized cables are but one manifestation of interior insulation damage. Our findings question the durability of the ethylene-tetrafluoroethylene cable coating on exposed cables.

Longevity of Sprint Fidelis Implantable Cardioverter-Defibrillator Leads and Risk Factors for Failure

Background— Sprint Fidelis (Fidelis) implantable cardioverter-defibrillator leads are prone to fractures that have caused adverse events, primarily inappropriate shocks, and a few reported deaths. More than 100 000 patients have Fidelis leads. No independent multicenter long-term performance information exists for this lead, and single-center studies suggest that certain patients are at increased risk for Fidelis failure. Our aim was to assess the longevity of Fidelis leads and to evaluate clinical variables and adverse events associated with Fidelis failure. The results were compared with like data for Quattro Secure (Quattro) implantable cardioverter-defibrillator leads implanted at our centers. Methods and Results— This 3-center study included adults ≥18 years of age who received Fidelis or Quattro leads for the prevention of sudden cardiac death. From November 2001 to January 2009,1023 Fidelis and 1668 Quattro leads were implanted and followed up. The failure rate for Fidelis leads was 2.81%/y compared with 0.43%/y for Quattro leads (P<0.0001). No deaths or injuries occurred as a result of lead failure, but 42% of fractures caused inappropriate shocks. The survival of Fidelis leads at 4 years was 87.0% (95% confidence interval, 83.6 to 90.1) compared with 98.7% (95% confidence interval, 97.9 to 99.4) for Quattro leads (P<0.0001). Multivariate predictors of Fidelis failure were younger age (hazard ratio, 0.98; 95% confidence interval, 0.96 to 0.99), female gender (hazard ratio, 0.61; 95% confidence interval, 0.40 to 1.00), and cardiac disease (P=0.041). Conclusions— Compared with Quattro leads, the survival of Fidelis leads continues to decline, and Fidelis failure is notably higher in younger patients, women, individuals with hypertrophic cardiomyopathy, and patients with arrhythmogenic right ventricular dysplasia or channelopathies. These findings have significant implications for the management of patients who have Fidelis leads, and they demonstrate the importance of weighing clinical variables in assessments of implantable cardioverter-defibrillator lead performance.

Failure of impedance monitoring to prevent adverse clinical events caused by fracture of a recalled high-voltage implantable cardioverter-defibrillator lead

BACKGROUND The Medtronic Sprint Fidelis implantable cardioverter-defibrillator high-voltage lead is prone to fracture. The October 2007 safety advisory recommended lead impedance monitoring to aid in identifying lead fractures. OBJECTIVE The aim of this single-center study was to examine the effectiveness of impedance monitoring for detecting Sprint Fidelis lead failures before they caused adverse clinical events such as inappropriate shocks. METHODS Impedance and sensing information were acquired during routine clinic and CareLink follow-up and at the time of lead failure using the Patient Alert, sensing integrity counter, nonsustained episode, and electrogram features in Medtronic pulse generators. RESULTS Between September 2004 and February 2008, 17 of 514 Sprint Fidelis leads (3.3%) followed up at our center failed between 11 and 35 months after implantation (mean 23.0 +/- 8.0 months). Fifteen of these failures (88%) were caused by pace-sense conductor fractures, and 2 (12%) were caused by high-voltage conductor defects. Twelve of 15 patients (80%) with pace-sense conductor fractures received inappropriate shocks; of these, 4 had no significant increase in lead impedance before they were shocked, 2 were shocked <3 hours after their lead impedances exceeded the 1,000 Omega audible alert threshold, and 2 patients did not hear the alarm. All pace-sense conductor failures whose sensing function could be evaluated (13 of 15) had oversensing based on stored data, and oversensing usually (11 of 13) preceded impedances changes. CONCLUSION Impedance monitoring did not prevent inappropriate shocks in two-thirds of our patients. Thus, pace-sense conductor impedance monitoring as currently implemented does not reliably forewarn patients of a lead malfunction. Consequently, patients who have Sprint Fidelis leads remain at risk for adverse clinical events associated with pace-sense conductor fracture.

Deaths caused by the failure of Riata and Riata ST implantable cardioverter-defibrillator leads.

BACKGROUND Riata and Riata ST leads (St Jude Medical, Sylmar, CA) were recalled in 2011. These leads are prone to externalized conductors. However, it is electrical malfunctions that may result in serious adverse events, including death. OBJECTIVE To assess the deaths of patients with Riata and Riata ST leads that have been reported to the Food and Drug Administration to determine whether they were due to lead malfunction. A similar analysis was performed for Quattro Secure leads (Medtronic, Inc, Minneapolis, MN). METHODS In February 2012, we searched the Food and Drug Administrations Manufacturers and User Facility Device Experience database for deaths associated with Riata, Riata ST, and Quattro Secure leads. A lead-related death was a sudden or unexpected death accompanied by evidence of lead malfunction; an indeterminate death was a death that was nonsudden or evidence of lead malfunction was not provided; a not lead-related death was a death that was nonsudden and/or there was no evidence that the lead contributed to the patients demise. RESULTS The Manufacturers and User Facility Device Experience database search found 133 deaths; of these, 22 were caused by Riata or Riata ST lead failure and 5 were caused by Quattro Secure lead failure. Riata and Riata ST lead failure deaths were typically caused by short circuits between high-voltage components. No death was due to externalized conductors. CONCLUSIONS Riata and Riata ST implantable cardioverter-defibrillator leads are prone to high-voltage failures that have resulted in death. These failures appeared to have been caused by insulation defects that resulted in short circuiting between high-voltage components. Externalized conductors were not a factor in these deaths.

Lessons From the Failure and Recall of an Implantable Cardioverter-Defibrillator

Multiple clinical trials have shown that a properly functioning implantable cardioverter-defibrillator (ICD) is capable of interrupting sudden death caused by ventricular tachyarrhythmias. Unfortunately, ICDs are complex medical devices, and they do not always perform as expected. For example, only 5% of ICD batteries last >7 years, and most dual-chamber ICD models must be replaced for battery depletion every 3 to 5 years.1 Normal battery depletion, however, is reliably predicted by routine follow-up methods before an ICD fails. In contrast, electronic malfunctions are unpredictable and may not be detected by standard follow-up techniques before an ICD is unable to deliver effective therapy. Thus, sudden cardiac arrest or death may be the first and only sign that an ICD has failed.2 Recently, we reported the death of a 21-year-old patient who received a Prizm 2 DR model 1861 ICD pulse generator (Guidant, Inc) in 2001 to prevent sudden cardiac death resulting from hypertrophic cardiomyopathy.3 In March 2005, this young man experienced a witnessed arrest and could not be resuscitated. His ICD was returned to Guidant, which found that the device had failed during the delivery of a shock. The cause of failure was massive electronic damage caused by electrical overstress that occurred when a short circuit developed between a high-voltage wire and a tube used to test the housing during manufacturing (see the Figure). At the time of our patient’s death, Guidant had knowledge of 25 similar Prizm 2 DR model 1861 failures in patients, 3 of whom had required rescue defibrillation. Indeed, Guidant had first observed this mode of failure 3 years earlier, in February 2002, when 2 returned Prizm 2 DR pulse generators exhibited the same short circuiting that caused our patient’s device to fail. Guidant was sufficiently concerned about these failures that manufacturing changes were made …