Hypokalemia unmasking underlying premature ventricular contraction induced polymorphic ventricular tachycardia: Low potassium is not always the culprit!

Hypokalemia is prevalent in patients resuscitated from out-of-hospital cardiac arrest and can contribute to polymorphic ventricular tachycardia (PMVT) by prolonging the QT interval. We present an interesting scenario of malignant ventricular arrythmia initially attributed to moderate hypokalemia that persisted after correction of potassium. Subsequent electrophysiological study showed two frequent PMVT-triggering PVCs mapped to the base of the antero-lateral papillary muscle and the para-Hisian region of the right side of the interventricular septum. The patient underwent catheter ablation to prevent further recurrences and dual chamber ICD implantation for secondary prevention.

Total laser cycles-a measure of transvenous lead extraction difficulty.

BACKGROUND: Several variables have been identified as predictors for difficult or complicated transvenous lead extraction (TLE), including age and number of implanted leads, as well as patient's age; however, a standard measure of TLE difficulty has not been described. OBJECTIVE: Total laser cycles (TLCs) delivered during laser-assisted TLE is an objective variable that could reflect the difficulty of TLE. This study investigated whether TLC is correlated with known predictors of difficult TLE. METHODS: In a retrospective study of TLE procedures using the laser sheath, we analyzed TLC delivered and compared it to established predictors of procedural failure and complications. RESULTS: Of 166 patients undergoing TLE, the laser sheath (SLS II or Glidelight, Spectranetics Inc.,) was used as the primary extraction sheath in 130 patients, and 100 patients had complete TLC data available. The mean age of the oldest lead (AOL) was 7.1 ± 3.2 years with a median of 6.91 (interquartile range [IQR] 0.48-16.69) years, and 1.6 ± 0.7 leads (range, 1-4) were extracted per procedure. Two thirds of procedures involved ICD leads. Clinical success was 99%, with one patient (1%) experiencing a major complication. Median TLC delivered was 1165 (IQR, 567-2062; range, 49-9522). TLC was positively correlated with AOL (r = 0.227, p = 0.023), and the combined age of leads was extracted (r = 0.307, p = 0.002). TLC was also positively correlated with number of leads extracted per procedure (ρ = 0.227, p = 0.024). There was a non-significant negative trend towards correlation between TLC and patient's age (r = -0.112, p = 0.268). CONCLUSION: TLC showed significant correlation with known predictors of difficulty during TLE using the laser sheath. TLC is an objective method to report the difficulty of TLE and could usefully be reported in future series of laser lead extractions.

Real-time guidewire localization using impedance-based electroanatomic mapping: experimental results and clinical validation during cryoballoon ablation of atrial fibrillation.

AIMS: Cryoballoon ablation is an emerging therapy for atrial fibrillation (AF). However, the Arctic Front cryoballoon (Medtronic) cannot be localized on current electroanatomic mapping (EAM) systems. We describe a technique to visualize guidewires in an impedance-based EAM system. METHODS AND RESULTS: A novel technique for real-time guidewire localization in an EAM (Ensite Velocity, St Jude Medical) was prospectively evaluated among patients referred for cryoballoon AF ablation. The guidewire was visualized as an 'orb' on the EAM and localization in each of the pulmonary veins (PVs) compared with orthogonal fluoroscopy, contrast venography, and intra-cardiac echocardiography. Application of the technique in 21 consecutive patients [median age 58 (interquartile range 21); 71.4% male; 85.7% paroxysmal AF] demonstrated agreement with respect to guidewire localization in 82 of 82 (100%) PVs. Discrimination of guidewire position in the left atrial appendage from the left PVs was also demonstrated. When compared with 21 consecutive cryoballoon procedures over the same time period in which the technique was not used, fluoroscopy time was reduced [median 53.2 (25.9) vs. 72.3 (47.6) min, P = 0.008], and a trend towards reduced radiation exposure [median 372 (656.0) vs. 581 (849.9) mGy, P = 0.08] was noted, without effect on acute procedural or mid-term endpoints. Ex vivo assessment of the technique in a saline bath left atrial model demonstrated that the 'orb' localizes to the centroid of the exposed portion of the guidewire. CONCLUSION: This simple, novel technique provides real-time, accurate guidewire localization to enable guidewire and catheter navigation during cryoballoon AF ablation.

Early risk of mortality after coronary artery revascularization in patients with left ventricular dysfunction and potential role of the wearable cardioverter defibrillator.

BACKGROUND: Implantation of implantable cardioverter defibrillator for prevention of sudden cardiac death is deferred for 90 days after coronary revascularization, but mortality may be highest early after cardiac procedures in patients with ventricular dysfunction. We determined mortality risk in postrevascularization patients with left ventricular ejection fraction ≤35% and compared survival with those discharged with a wearable cardioverter defibrillator (WCD). METHODS AND RESULTS: Hospital survivors after surgical (coronary artery bypass graft surgery) or percutaneous (percutaneous coronary intervention [PCI]) revascularization with left ventricular ejection fraction ≤35% were included from Cleveland Clinic and national WCD registries. Kaplan-Meier, Cox proportional hazards, propensity score-matched survival, and hazard function analyses were performed. Early mortality hazard was higher among 4149 patients discharged without a defibrillator compared with 809 with WCDs (90-day mortality post-coronary artery bypass graft surgery 7% versus 3%, P=0.03; post-PCI 10% versus 2%, P<0.0001). WCD use was associated with adjusted lower risks of long-term mortality in the total cohort (39%, P<0.0001) and both post-coronary artery bypass graft surgery (38%, P=0.048) and post-PCI (57%, P<0.0001) cohorts (mean follow-up, 3.2 years). In propensity-matched analyses, WCD use remained associated with lower mortality (58% post-coronary artery bypass graft surgery, P=0.002; 67% post-PCI, P<0.0001). Mortality differences were not attributable solely to therapies for ventricular arrhythmia. Only 1.3% of the WCD group had a documented appropriate therapy. CONCLUSIONS: Patients with left ventricular ejection fraction ≤35% have higher early compared to late mortality after coronary revascularization, particularly after PCI. As early hazard seemed less marked in WCD users, prospective studies in this high-risk population are indicated to confirm whether WCD use as a bridge to left ventricular ejection fraction improvement or implantable cardioverter defibrillator implantation can improve outcomes after coronary revascularization.

Impact of a national smoking ban on hospital admission for acute coronary syndromes: a longitudinal study.

BACKGROUND: A ban on smoking in the workplace was introduced in Ireland on March 29, 2004. As exposure to secondhand smoke has been implicated in the development of coronary disease, this might impact the incidence of acute coronary syndromes (ACS). HYPOTHESIS: The smoking ban was associated with a decreased rate of hospital admissions for ACS. METHODS: We analyzed data collected in a registry of all patients admitted to hospital with ACS in the southwest of Ireland, catchment population 620 525, from March 2003 until March 2007. RESULTS: In the year following implementation of the ban, there was a significant 12% reduction in ACS admissions (177.9 vs 205.9/100,000; 95% confidence interval [CI]: 164.0-185.1, P = 0.002). This reduction was due to fewer events occurring among men (281.5 vs 233.5, P = 0.0011) and current smokers (408 vs 302 admissions, P < 0.0001). There was no change in the rate of admissions for ACS in the following year (174.3/100,000; 95% CI: 164.0-185.1, P > 0.1). However, a further 13% reduction was observed between March 2006 and March 2007 (149.2; 95% CI: 139.7-159.2). Variation in admissions with time as a continuous variable also demonstrated a reduction on implementation of the smoking ban. CONCLUSIONS: A national ban on smoking in public places was associated with an early significant decrease in hospital admissions for ACS, suggesting a rapid effect of banning smoking in public places on ACS. A further reduction of similar magnitude 2 years after implementation of the ban is consistent with a longer-term effect that should be further examined in long-term studies.

Autoimmune hepatitis in association with lymphocytic colitis.

Autoimmune hepatitis is a rare, chronic inflammatory disorder which has been associated with a number of other auto-immune conditions. However, there are no reports in the medical literature of an association with microscopic (lymphocytic) colitis. We report the case of a 53-year-old woman with several autoimmune conditions, including lymphocytic colitis, who presented with an acute hepatitis. On the basis of the clinical features, serology, and histopathology, we diagnosed autoimmune hepatitis. To our knowledge, this is the first report of autoimmune hepatitis in association with lymphocytic colitis, and lends support to the theory of an autoimmune etiology for lymphocytic colitis.