Salah S. Al-Zaiti

A Low-Glycemic Nutritional Fitness Program to Reverse Metabolic Syndrome in Professional Firefighters: Results of a Pilot Study

Background:The risk for cardiovascular events is higher for those with metabolic syndrome (MetS), and it is known that firefighters have a 4-fold risk for cardiovascular events. The purpose of this study was to quantify MetS prevalence and evaluate the effect of a low-glycemic nutritional fitness program on the reduction of MetS risk factors among firefighters. Methods:Professional firefighters were screened for MetS then enrolled in a low-glycemic nutritional fitness program for a 12-week period. Anthropometric and physiological measurements were obtained at the start and end of the program. Subjects with 3 or more of the following were positive for MetS: waist-40-inches or greater (men) or 35 inches or greater (women), blood pressure 135 mm Hg or greater (systole) or 85 mm Hg or greater (diastole), fasting blood sugar 100 mg/dL or greater, triglycerides 150 mg/dL or greater, and high-density lipoproteins less than 40 mg/dL (men) or less than 50 mg/dL (women). Weekly sessions provided low-glycemic nutrition instruction, fitness training, and evaluation of individual progress. Results:Seventy-five firefighters (aged 42 [SD, 8] years, mostly white men) had a total MetS prevalence of 46.7% (P < .05 vs normal population). One platoon (10 men, aged 48 [SD, 5] years) was enrolled in the 12-week program. Most (7/10) had MetS at the baseline, but this prevalence decreased significantly after 12 weeks to 3 subjects (P = .02). On average, subjects had 3.2 (SD, 1.6) versus 1.9 (SD, 1.7) MetS risk factors (P < .01) at baseline and the 12-week interval, respectively. Conclusions:The prevalence of MetS and MetS risk factors is higher among professional firefighters compared with the general population. A short-duration, low-glycemic fitness program can successfully improve anthropometric and physiological measures and reduce the prevalence of MetS.

Increased T wave complexity can indicate subclinical myocardial ischemia in asymptomatic adults

BACKGROUND Altered ventricular repolarization and cardiovascular mortality are closely correlated, and recent novel findings show that a distorted T wave loop morphology is also strongly correlated with subsequent onset of myocardial infarction among patients with stable angina. Therefore, we hypothesized that an abnormal T wave complexity ratio (CR) can indicate vulnerability to myocardial ischemia in asymptomatic, apparently healthy adults. METHODS Healthy firefighters were enrolled in the current investigation where they completed symptom-limited, graded exercise treadmill testing (ETT) and 24-hour Holter electrocardiogram recording. The CR was automatically calculated using principal component analysis of the high-resolution Holter electrocardiogram signal then averaged over 24 hours (CR(24h)). End points were manually analyzed from the ETT; recordings revealing horizontal ST-segment depression (≥ 1 mm) in 2 or more leads for at least 1 minute during the peak of exercise were considered indicators of myocardial ischemia. RESULTS One hundred four firefighters (age, 44 ± 8 years; 96% men) completed both ETT and Holter recording. Firefighters with positive end points (n = 34, or 33%) had higher CR(24h) compared with those with negative end points (0.14 ± 0.06 vs 0.09 ± 0.04, P < .01); there were no demographic differences between the 2 groups. After controlling for age, smoking status, hypertension, and obesity, an abnormal CR(24h) (≥ 20%) significantly predicted exercise-induced myocardial ischemia (odds ratio, 4.6; P = .01). CONCLUSIONS Increased T wave CR(24h) can predict myocardial ischemia in asymptomatic middle-age adults; this suggests that the distorted T wave loop morphology can reflect an altered ventricular repolarization caused by prolonged subclinical myocardial ischemia possibly caused by early coronary artery disease.

The Selvester QRS Score is more accurate than Q waves and fragmented QRS complexes using the Mason-Likar configuration in estimating infarct volume in patients with ischemic cardiomyopathy

Infarct volume independently predicts cardiovascular events. Fragmented QRS complexes (fQRS) may complement Q waves for identifying infarction; however, their utility in advanced coronary disease is unknown. We tested whether fQRS could improve the electrocardiographic prediction of infarct volume by positron emission tomography in 138 patients with ischemic cardiomyopathy (ejection fraction, 0.27 +/- 0.09). Indices of infarction (pathologic Q waves, fQRS, and Selvester QRS Score) were analyzed by blinded observers. In patients with QRS duration less than 120 milliseconds, number of leads with pathologic Q waves (mean, 1.6 +/- 1.7) correlated weakly with infarct volume (r = 0.30, P < .05). Adding fQRS increased the number of affected leads (3.6 +/- 2.5), but the significant correlation with infarct volume was lost (r = 0.02, P = .10). Selvester Score was the most accurate (mean, 5.9 +/- 4.9 points; r = 0.49; P < .001). Fragmented QRS was not predictive of infarct size in patients with QRS duration of at least 120 milliseconds (r = 0.02, P = .19). Thus, in ischemic cardiomyopathy, consideration of fQRS complexes does not improve Q wave prediction of infarct volume; but Selvester Score was more accurate.

Novel technical solutions for wireless ECG transmission & analysis in the age of the internet cloud ☆

Current guidelines recommend early reperfusion therapy for ST-elevation myocardial infarction (STEMI) within 90 min of first medical encounter. Telecardiology entails the use of advanced communication technologies to transmit the prehospital 12-lead electrocardiogram (ECG) to offsite cardiologists for early triage to the cath lab; which has been shown to dramatically reduce door-to-balloon time and total mortality. However, hospitals often find adopting ECG transmission technologies very challenging. The current review identifies seven major technical challenges of prehospital ECG transmission, including: paramedics inconvenience and transport delay; signal noise and interpretation errors; equipment malfunction and transmission failure; reliability of mobile phone networks; lack of compliance with the standards of digital ECG formats; poor integration with electronic medical records; and costly hardware and software pre-requisite installation. Current and potential solutions to address each of these technical challenges are discussed in details and include: automated ECG transmission protocols; annotatable waveform-based ECGs; optimal routing solutions; and the use of cloud computing systems rather than vendor-specific processing stations. Nevertheless, strategies to monitor transmission effectiveness and patient outcomes are essential to sustain initial gains of implementing ECG transmission technologies.

Clinical Utility of Ventricular Repolarization Dispersion for Real‐Time Detection of Non‐ST Elevation Myocardial Infarction in Emergency Departments

Background A specific electrocardiographic (ECG) marker of ischemia would greatly improve the speed and accuracy of detecting and treating non-ST elevation myocardial infarction (NSTEMI). We hypothesize that ischemia induces ventricular repolarization dispersion (VRD), altering the T-wave before any ST segment deviation. We sought to evaluate the clinical utility of VRD to (1) detect NSTEMI cases in the emergency department (ED) and (2) identify NSTEMI cases at high risk for in-hospital major adverse cardiac events (MACEs). Methods and Results We continuously recorded 12-lead Holter ECGs from chest pain patients upon their arrival to the ED. VRD was quantified using principal component analysis of the 12-lead ECG to compute a T-wave complexity ratio (ie, ratio of second to first eigenvectors of repolarization). Clinical outcomes were obtained from hospital records. The sample was composed mainly of older males (n=369; ages 63±12 years; 63% males), and 92 (25%) had NSTEMI and 26 (7%) had MACEs. Baseline T-wave complexity ratio modestly correlated with peak troponin levels (r=0.41; P<0.001) and was a good classifier of NSTEMI events (area under the curve=0.70). An increased T-wave complexity ratio on the presenting ECG was strongly associated with NSTEMI (odds ratio [OR]=3.8 [2.1 to 5.8]) and in-hospital MACE (OR=8.2 [3.1 to 21.5]). Conclusions A simple measure of global VRD on the presenting 12-lead ECG correlates with ischemic myocardial injury and can discriminate NSTEMI cases very early during evaluation. Prospective studies should validate these findings and test whether VRD can guide therapy.

Paroxysmal Supraventricular Tachycardia: Pathophysiology, Diagnosis, and Management.

Paroxysmal supraventricular tachycardia (PSVT) is a well-known and thoroughly studied clinical syndrome, characterized by regular tachycardia rhythm with sudden onset and abrupt termination. Most patients present with palpitations and dizziness, and their electrocardiogram demonstrates a narrow QRS complex and regular tachycardia with hidden or inverted P waves. PSVT is caused by re-entry due to the presence of inhomogeneous, accessory, or concealed conducting pathways. Hemodynamically stable patients are treated by vagal maneuvers, intravenous adenosine, diltiazem, or verapamil, hemodynamically unstable patients are treated by cardioversion. Patients with symptomatic and recurrent PSVT can be treated with long-term drug treatment or catheter ablation.

Electrocardiographic Responses During Fire Suppression and Recovery Among Experienced Firefighters.

Objective: We sought to evaluate the impact of high-intensity exertion and heat stress on electrocardiographic changes during fire suppression and recovery. Methods: Healthy firefighters completed a live-fire training evolution. Each firefighter was randomly assigned to complete either two or three intervals of fire suppression tasks followed by a structured recovery. Firefighters were continuously monitored using 12-lead Holter electrocardiogram. Results: Most firefighters (71.4%) exceeded their maximum heart rate and one third had pathological ST events. Nearly one third of each of these abnormalities persisted throughout recovery period. Longer fire suppression intervals did not affect the incidence of these abnormalities. Conclusions: Fire suppression is associated with ST-segment changes among firefighters at low risk for cardiovascular disease. These abnormalities continued into initial recovery even though cooling and rehydration were provided.

Rationale, development, and implementation of the Electrocardiographic Methods for the Prehospital Identification of Non-ST Elevation Myocardial Infarction Events (EMPIRE)

BACKGROUND The serum rise of cardiac troponin remains the gold standard for diagnosing non-ST elevation (NSTE) myocardial infarction (MI) despite its delayed response. Novel methods for real-time detection of NSTEMI would result in more immediate initiation of definitive medical therapy and faster transport to facilities that can provide specialized cardiac care. METHODS EMPIRE is an ongoing prospective, observational cohort study designed to quantify the magnitude of ischemia-induced repolarization dispersion for the early detection of NSTEMI. In this ongoing study, prehospital ECG data is gathered from patients who call 9-1-1 with a chief complaint of non-traumatic chest pain. This data is then analyzed using the principal component analysis (PCA) technique of 12-lead ECGs to fully characterize the spatial and temporal qualities of STT waveforms. RESULTS Between May and December of 2013, Pittsburgh EMS obtained and transmitted 351 prehospital ECGs of the 1149 patients with chest pain-related emergency dispatches transported to participating hospitals. After excluding those with poor ECG signal (n=40, 11%) and those with pacing or LBBB (n=50, 14%), there were 261 eligible patients (age 57±16years, 45% female, 45% Black). In this preliminary sample, there were 19 STEMI (7%) and 33 NSTEMI (12%). More than 50% of those with infarction (STEMI or NSTEMI) had initially negative troponin values upon presentation. We present ECG data of such NSTEMI case that was identified correctly using our methods. CONCLUSIONS Concrete ECG algorithms that can quantify NSTE ischemia and allow differential treatment based on such ECG changes could have an immediate clinical impact on patient outcomes. We describe the rationale, development, design, and potential usefulness of the EMPIRE study. The findings may provide insights that can influence guidelines revisions and improve public health.

Electrocardiogram-based predictors of clinical outcomes: a meta-analysis of the prognostic value of ventricular repolarization.

OBJECTIVES To estimate age- and sex-specific prognostic values of eight electrocardiographic repolarization descriptors to predict various mortality endpoints. BACKGROUND Using electrocardiographic markers for risk stratification is well studied; however, the prognostic value of many markers is controversial, and their clinical utility remains debatable. No meta-analyses exist that address the prognostic value of ECG markers. METHODS Data were synthesized from 106 primary studies using a random-effect variance model. Age and sex subgroups were analyzed using sensitivity analysis. RESULTS Four classic (i.e., duration, amplitude, inversion, and ST-T changes) and four novel (i.e., axis, loop, wavefront direction, and waveform complexity) repolarization descriptors were studied. These novel descriptors were particularly useful in predicting sudden death. Abnormal repolarization duration, vectors, and loops have greater impact on negative cardiovascular outcomes in women compared to men; additionally, ischemic repolarization changes have greater impact on negative cardiovascular outcomes in younger versus older adults. CONCLUSIONS Assessing repolarization abnormalities is particularly helpful in women and younger adults. Researchers need to further explore the clinical utility of these abnormalities in management algorithms.

The prognostic value of discordant T waves in lead aVR: A simple risk marker of sudden cardiac arrest in ischemic cardiomyopathy

BACKGROUND Simple and reliable ECG marker(s) for sudden cardiac arrest (SCA) could be very useful in assessing high-risk populations. Since ischemic repolarization abnormalities in the left ventricular (LV) apex are strongly correlated with discordant T waves in lead aVR, we sought to evaluate the clinical and prognostic significance of this feature in ischemic cardiomyopathy. METHODS The PAREPET trial enrolled patients with ischemic cardiomyopathy eligible for a primary prevention implantable cardiac defibrillator (ICD). Those with persistent pacing or left bundle branch block were excluded. Amplitudes of T/aVR were automatically computed from median ECG beats at enrollment and endpoints were blindly adjudicated. RESULTS The sample was mainly composed of older men (n=138, age 65±12, 91% male, EF 29±9%). At enrollment, amplitude of T/aVR significantly correlated with EF, indexed LV end-diastolic volume, B-type natriuretic peptide (BNP), regional scar volume, and PET-quantified denervated myocardium. After a median follow up of 4.2years, there were 23 (17%) adjudicated SCA. In multivariate analysis, the presence of discordant T/aVR (>0mm, n=42, 30%) was a significant and independent predictor of SCA (hazard ratio 2.0 [95% CI 1.0-4.9]) and cardiac death (hazard ratio 1.9 [95% CI 1.0-3.7]). CONCLUSIONS In subjects with ischemic cardiomyopathy, discordant T waves in lead aVR are associated with high-risk clinical parameters including lower ejection fraction, greater ventricular volume, higher BNP, and more denervated myocardium. Furthermore, discordant T/aVR remained an independent predictor of SCA and cardiovascular mortality even after accounting for these prognostic factors.