Salman A. Haq

Late Presentation of a Lead Perforation as a Complication of Permanent Pacemaker Insertion

Lead perforation is a less-recognized delayed complication of device implantation. Delay in recognition may prove fatal. Predictors of postimplantation pericardial effusion, which serves as a marker of perforation, include concomitant use of transvenous pacemaker, steroid use within 7 days, and older age. The authors report a case of an 86-year-old patient who presented with a lead perforation 16 months following the original pacemaker insertion. Following surgical repair with sternotomy, a new ventricular lead was placed via a transvenous approach at the right ventricular septum. A higher clinical suspicion should be maintained in the elderly in whom perforation occurs more frequently, and consideration should be given to implanting the lead in sites other than the right ventricular apex to minimize the risk of this late complication.

Effect of obstructive sleep apnea on QT dispersion: a potential mechanism of sudden cardiac death.

Objectives: QT dispersion (QT_d) measures the variability of the ventricular recovery time. QT_d may identify patients at risk for ventricular arrhythmias and sudden cardiac death (SCD). The purpose of our study was to determine the effect of obstructive sleep apnea (OSA) on QT_d. Methods: There were 199 patients studied: 101 patients (28 women, 73 men) with OSA diagnosed in our sleep center and 98 patients (49 women, 49 men) without OSA from the outpatient clinic, representing the control group. QT intervals (milliseconds) were measured in each of the 12 leads of a standard surface electrocardiogram during wakefulness and QT_d calculated (QT_max – QT_min). QT^c_d, which corrects for heart rate, was also calculated. Results: Mean age and heart rate were similar in men and women with or without OSA. Control patients exhibited a significant difference (p < 0.001) in QT_d between men (48 ± 19) and women (31 ± 13). Men and women with OSA had similar QT_d (56 ± 35 vs. 54 ± 21) but higher QT_d compared to the control group. QT^c_d results were similar to QT_d. Conclusions: Patients with OSA and no structural heart disease have a higher QT_d/QT^c_d compared to an overtly healthy patient population, possibly serving as a marker for an increased risk of SCD.

Long-term Effect of Chronic Oral Anticoagulation with Warfarin after Acute Myocardial Infarction

BACKGROUND Antiplatelet therapy is the principal component of the antithrombotic regimen after acute myocardial infarction. It remains unclear whether additional chronic oral anticoagulation (OAC) improves outcomes. We set out to evaluate the risk and benefit of long-term OAC after myocardial infarction. METHODS We pooled 10 randomized clinical trials comparing warfarin-containing regimens (OAC) with or without aspirin with non-OAC regimens with or without aspirin (No OAC) for patients with recent infarction. The primary endpoint was all-cause mortality. Other endpoints included recurrent infarction, stroke, and major bleeding. We calculated the odds ratio (OR) (fixed effect, OR <1 indicates benefit for OAC) for death and other ischemic and hemorrhagic complications at the longest interval of follow-up available. RESULTS Among 24,542 patients, 14,062 were assigned to OAC and 10,480 to no OAC. The patients were followed for 3-63 months, for 89,562 patient-years. Death occurred in 2424 patients (9.9%), 1279 OAC patients, and 1145 in the no OAC group, OR 0.97 (95% confidence interval [CI], 0.88-1.05), P=.43. Similarly, there was no effect on recurrent infarction. Stroke occurred in 578 patients (2.4%), 271 in the OAC group and 307 in the no OAC group, OR 0.75 (95% CI, 0.63-0.89), P=.001. There was substantially more major bleeding (OR 1.83 [95% CI, 1.50-2.23], P <.001) in the OAC group. Separate analyses, performed for patients (n=11,920) randomized to aspirin versus aspirin and OAC yielded very similar results. CONCLUSION As compared with placebo or aspirin, OAC with or without aspirin does not reduce mortality or reinfarction, reduces stroke, but is associated with significantly more major bleeding.

Effect of renal function loss on NT-proBNP level variations

OBJECTIVE NT-proBNP level is used for the detection of acute CHF and as a predictor of survival. However, a number of factors, including renal function, may affect the NT-proBNP levels. This study aims to provide a more precise way of interpreting NT-proBNP levels based on GFR, independent of age. METHODS This study includes 247 pts in whom CHF and known confounders of elevated NT-proBNP were excluded, to show the relationship of GFR in association with age. The effect of eGFR on NT-proBNP level was adjusted by dividing 1000 x log(NT-proBNP) by eGFR then further adjusting for age in order to determine a normalized NT-proBNP value. RESULTS The normalized NT-proBNP levels were affected by eGFR independent of the age of the patient. CONCLUSION A normalizing function based on eGFR eliminates the need for an age-based reference ranges for NT-proBNP.

Torsade De Pointes: An Electrophysiological Effect of Cardiac Resynchronization?

Case Presentation A 74-year-old Hispanic woman with history of nonischemic cardiomyopathy, left ventricular ejection fraction of 20%, remote cerebrovascular accident, was referred for cardiac resynchronization therapy (CRT), due to the presence of refractory heart failure in spite of optimal medical therapy, and left bundle branch block on the surface electrocardiogram (ECG) (Fig. 1). She successfully underwent implantation of a Medtronic Insync III 8042 (Minneapolis, MN, USA) biventricular pacemaker. A postoperative ECG obtained at 6:00 p.m. documented appropriate atrial sensing and capture of both ventricles. The patient was monitored on telemetry. Approximately 1 hour later, QT prolongation developed and was associated with ventricular bigeminy (Fig. 2). Shortly afterwards, multiple runs of polymorphic ventricular tachycardia/ torsade de pointes (VT/TdP) were recorded. Electrolyte abnormalities and drug effects were ruled out. Given the persistence of ventricular tachyarrhythmias for several hours, a decision was made to discontinue left ventricular pacing. This resulted into immediate disappearance of ventricular ectopy, with no arrhythmia recurrence during right ventricular pacing or spontaneous atrioventricular conduction. QT interval returned to baseline shortly after discontinuation of left ventricular pacing. No further attempts were made to perform left ventricular or biventricular pacing.

The case of the disappearing myxoma

We present a case demonstrating the utility of cardiovascular magnetic resonance (CMR) in the diagnosis of a cardiac mass. A 70-year-old female who presented with chest pressure and left sided jaw pain was found to have a cardiac mass on transthoracic and transesophageal echocardiography that was diagnosed as an atrial myxoma. A cardiac magnetic resonance test determined the mass to be more consistent with a thrombus than a myxoma through a stepwise approach using multiple pulse sequences. Thus, unwarranted and potentially risky thoracic surgery was avoided by the incorporation of a systematic evaluation by cardiac MRI.

Incidence of caffeine in serum of patients undergoing dipyridamole myocardial perfusion stress test by an intensive versus routine caffeine history screening.

The coronary vasodilatory effect of dipyridamole is competitively blocked by caffeine. The purposes of this study were to (1) assess the incidence of having detectable serum caffeine and (2) evaluate whether an intensive caffeine history screening strategy was superior to routine history screening before dipyridamole myocardial perfusion imaging. One hundred ninety-four patients who were randomized to an intensive or a routine screening history strategy were prospectively evaluated. Serum caffeine levels were determined in all patients. Outcomes data, including death, nonfatal myocardial infarction, and history of revascularization, were obtained at 24 months. Nearly 1 in 5 patients (19%) who screened negative by history had detectable serum caffeine. In patients who screened negative by history, there was no statistically significant difference in the percentage of caffeine seropositivity between the intensive and routine arms (16% vs 22%, respectively, p = 0.31). The incidence of combined end points of death, myocardial infarction, or revascularization was 22.9% and 7.3% in patients with and without detectable serum caffeine, respectively (p = 0.01). In conclusion, despite initial negative results on screening by history, a considerably high percentage of patients had positive serum caffeine levels. These results do not support the use of an intensive screening strategy. Detectable serum caffeine was associated with a higher incidence of adverse outcomes.

Enhancing the Diagnostic Performance of Troponins in the Acute Care Setting

BACKGROUND Current guidelines define cardiac troponin I (TnI) as an indicator of necrosis when the concentration exceeds the 99% upper limit of a healthy reference population, a reference value near the assays lowest detectable level. We assessed the utility of a modified TnI cutoff point derived from a population at low risk for coronary artery disease (CAD) and evaluated its utility in determining acute myocardial infarction (MI). METHODS A modified TnI cutoff point was derived by the receiver operating characteristic (ROC) curve from 737 consecutive patients who underwent serial TnI measurements for exclusion of MI. Creatinine kinase isoenzyme MB (CK-MB) evolutionary change was used to define MI. The new derived cutoff point was validated using another subset of 320 patients who were evaluated for MI. RESULTS ROC-derived TnI cutoff point (A) was 0.65 μg/L, and its performance was compared to the recommended cutoff point ([B] 0.15 μg/L). Cutoff point A had greater specificity (94.5% vs. 86.9%, p < 0.001) but slightly lower sensitivity (96.5% vs. 100%, p < 0.01). Cutoff point A provided significantly greater positive predictive value (PPV) for MI (74.1% vs. 55.5%, p < 0.0001) and fewer false-positive errors, while preserving comparable negative predictive value (NPV) (98.9% vs. 100%). CONCLUSION A higher cutoff point derived from a reference population of patients at low risk for CAD may improve the TnI performance assay. The PPV for diagnosis of MI was significantly higher and false-positive values were fewer without affecting the NPV. The more reliable diagnosis of MI may have resulted, which, in turn, may have significant clinical and economic implications.

Acute upper extremity arterial occlusion: A novel role for the use of rheolytic thrombectomy and intravascular ultrasound

Acute peripheral arterial occlusion may be caused by thrombosis or embolism. The objectives of therapy are to preserve limb and life by restoration of blood flow. Thrombolytic therapy has been the mainstay, but is limited by a high risk of bleeding. Surgical treatment, often required, is invasive with higher rates of morbidity and mortality. Rheolytic thrombectomy offers a percutaneous means of thrombus removal. A 62‐year‐old man with chronic atrial fibrillation, idiopathic dilated cardiomyopathy, and hypothyroidism presented with sudden onset of left arm pain. His medications included warfarin, digoxin, amiodarone, and synthroid. Examination revealed a harsh 3/6 systolic nonradiating murmur. The left arm was cold and weak with absent pulses. Laboratory data showed a prothrombin time (PT) of 12 sec and an international normalized ratio of 1.4. After heparinization, angiography was performed, showing a total occlusion of the brachial artery. A rheolytic thrombectomy catheter (RTC) was introduced to remove the thrombus. The RTC run time was 90 sec. Flow was restored to the vessel, but sluggish with angiographic evidence of stenosis. Intravascular ultrasound was performed, revealing a high‐grade fibromuscular stenosis. Balloon angioplasty was performed, followed by intracatheter injection of alteplase restoring normal flow. Sudden arterial occlusion is a medical emergency, which can result in limb loss. RTCs have demonstrated a reduced need for thrombolytic agents and surgical intervention, thereby decreasing complications, procedural time, and resource utilization. While most reports have focused on infra‐aortic thromboses, this case highlights its utility in the arm.

Gatifloxacin induced torsades de pointes.

The authors present an unusual case of torsades de pointes in an elderly woman treated with intravenous gatifloxacin antibiotic therapy.