Regional wall-motion abnormalities on post-stress electrocardiographic-gated technetium-99m sestamibi single-photon emission computed tomography imaging predict cardiac events.

BACKGROUND: The global left-ventricular (LV) ejection fraction (EF) is a powerful predictor of cardiac death (CD). There are limited data on the prognostic value of regional LV function. We examined the role of visually assessed regional wall motion in risk stratification for future cardiac events. METHODS AND RESULTS: A prospectively gathered database of 10,336 patients who underwent technetium (Tc)-99m sestamibi-gated single-photon emission computed tomography (SPECT) was analyzed. The summed stress score (SSS) and summed wall-motion score (SWMS) were calculated using a standard 17-segment model. The post-stress EF was generated using QGS software. The follow-up was 90.2% complete over 28.6 +/- 16 months. Patients with early (or=5) was an independent predictor of cardiac death (odds ratio = 1.78, 95% confidence interval = 1.11 to 2.85, P = .016). Among patients with an EF >or=45%, abnormal wall motion was the only gated SPECT variable that independently predicted cardiac death (odds ratio = 1.69, 95% confidence interval = 1.06 to 2.7, P = .028). In patients with an EF >or=45% and reversible perfusion defects, abnormal wall motion predicted an intermediate (2.2%/year) risk for CD, and a high (4.2%/year) risk for the combined endpoint of cardiac death and nonfatal MI. CONCLUSIONS: Regional LV function data from gated SPECT provide important prognostic information, and may identify a subgroup of patients with preserved EF and ischemia who are at significant risk for future cardiac events.

The congenital long QT syndrome and implications for young athletes.

The congenital long QT syndrome (LQTS) is caused by cardiac ion channel mutations, which predispose young individuals to sudden cardiac death often related to exercise. The issue of LQTS and sports participation has received significant publicity due to reports of sudden death in young competitive athletes. This article reviews the pathophysiology, clinical characteristics, and management of LQTS in the physically active and athletic population.

Cardiac tamponade as a result of Mycobacterium avium-complex pleural effusion.

Patients with advanced AIDS are prone to opportunistic infections, including disseminated disease from Mycobacterium avium-complex (MAC). We describe the first reported case of MAC related pleural effusion causing cardiac tamponade.

Intraoperative hypothermia increased defibrillation energy requirements.

We describe two patients with newly implanted automatic implantable cardioverter-defibrillators that had excessive defibrillation thresholds associated with hypothermia at intraoperative defibrillation threshold testing. Normal defibrillation threshold levels were obtained during postoperative non-invasive electrophysiology testing in an electrophysiology laboratory when the patients were normothermic. We hypothesize that inadvertent intraoperative hypothermia during device implantation may increase the defibrillation threshold.

Implantation of a biventricular pacing and defibrillator device via a persistent left superior vena cava.

A persistent left superior vena cava was discovered in a 66-year-old man with heart failure undergoing implantation of a biventricular pacing and defibrillator device. An active fixation right ventricular defibrillator lead was placed through a curved guiding catheter. A sub-selection catheter and a guidewire allowed the engagement of a posterior-lateral branch of the coronary sinus, performance of an angiogram without an occlusive balloon, and optimal lead placement. The right atrial lead was positioned using a standard stylet. Despite the technical challenges, implantation of a biventricular pacing and defibrillator device via a persistent left superior vena cava is safe and feasible.

Pharmacologic radionuclide myocardial perfusion imaging.

Pharmacologic stress testing with myocardial perfusion imaging has enabled patients who cannot complete adequate exercise to undergo diagnostic and prognostic evaluation for coronary artery disease. Pharmacologic stress agents belong to two groups: vasodilators (such as adenosine and dipyridamole), and inotropes (such as dobutamine). All have similar sensitivity (89%-91%) and specificity (78%-86%) for the diagnosis of coronary disease. For risk stratification, the risk of future cardiac events is related to the extent and severity of perfusion abnormalities. Pharmacologic stress testing permits risk stratification as early as 1 to 4 days following an acute myocardial infarction, and is superior to exercise stress testing in this regard. Similarly, it identifies patients at high risk for perioperative cardiac events prior to noncardiac surgery. This review summarizes the current evidence available regarding the diagnostic and prognostic use of pharmacologic stress testing.

Acute resting myocardial perfusion imaging in patients with diabetes mellitus: results from the Emergency Room Assessment of Sestamibi for Evaluation of Chest Pain (ERASE Chest Pain) trial.

BACKGROUND: Resting myocardial perfusion imaging (MPI) improves the triage of patients presenting to the emergency department (ED) with symptoms suggestive of acute cardiac ischemia (ACI). In the ED setting the presence of diabetes mellitus (DM) is a predictor of ACI and hospitalization, but the role of resting MPI in patients with DM is unknown. METHODS AND RESULTS: A secondary data analysis of a prospective, multicenter, randomized, controlled trial of ED evaluation strategies in patients with symptoms suggestive of ACI and normal or nondiagnostic electrocardiograms was performed. In the main trial 2475 patients were randomized to receive either the usual ED evaluation strategy (n = 1260) or the usual strategy supplemented by results from resting MPI by use of single photon emission computed tomography (SPECT) technetium 99m sestamibi (n = 1215). Patients with diabetes (n = 341) were evaluated separately. Imaging results, final diagnoses, effect on triage, and prognostic value of the SPECT imaging were compared between diabetic and nondiabetic patients. Of the 341 patients with diabetes, 153 (45%) were randomized to the imaging strategy. Patients with DM had higher rates of hospitalization (66% vs 49.6%, P = .0001) and ACI (21.1% vs 12.0%, P < .001) than patients without DM. Among diabetic patients without ACI, the admission rate was 63% in the usual strategy group versus 54% in the imaging strategy group (relative risk [RR] = 0.91 [95% CI, 0.76-1.06]; P = .24). There was no difference in the magnitude of this reduced risk of admission compared with patients without DM (RR = 0.84 [95% CI, 0.77-0.92]; P = .0002 for patients without DM and P = .35 for interaction of diabetes and RR reduction). CONCLUSIONS: Acute resting MPI with Tc-99m sestamibi is associated with improved triage decision making in symptomatic ED patients with diabetes.