Feasibility of combining serial smartphone single-lead electrocardiograms for the diagnosis of ST-elevation myocardial infarction.

BACKGROUND: The rate-limiting step in STEMI diagnosis often is the availability of a 12-lead electrocardiogram (ECG) and its interpretation. The potential may exist to speed the availability of 12-lead ECG information by using commonly available mobile technologies. We sought to test whether combining serial smartphone single-lead ECGs to create a virtual 12-lead ECG can accurately diagnose STEMI. METHODS: Consenting patients presenting with symptoms consistent with a possible STEMI had contemporaneous standard 12-lead and smartphone '12-lead equivalent' ECG (produced by electronically combining serial single-lead ECGs) recordings obtained. Matched ECGs were evaluated qualitatively and quantitatively by a panel of blinded readers and classified as STEMI/STEMI equivalent (LBBB), Not-STEMI, or uninterpretable. Interpretable ECG pairs were graded as showing good, fair, or poor correlation. RESULTS: Two hundred four subjects (age = 60 years, males = 57%, STEMI activation = 45%) were enrolled from 5 international sites. Smartphone ECG quality was graded as good in 151 (74.0%), fair in 32 (15.7%), poor in 8 (3.9%), and uninterpretable in 13 (6.4%). A STEMI/STEMI equivalent diagnosis was identified by standard 12-lead ECG in 57/204 (27.9%) recordings. For all interpretable pairs of smartphone ECGs compared with standard ECGs (n = 190), the sensitivity, specificity, and positive and negative predictive values for STEMI/STEMI equivalent by smartphone were 0.89, 0.84, 0.70 and 0.95, respectively. CONCLUSIONS: A '12-lead equivalent' ECG obtained from multiple serial single-lead ECGs from a smartphone can identify STEMI with good correlation to a standard 12-lead ECG. This technology holds promise to improve outcomes in STEMI by enhancing the reach and speed of diagnosis and thereby early treatment.

ß-blocker dosage and outcomes after acute coronary syndrome.

BACKGROUND: Although ß-blockers increase survival in acute coronary syndrome (ACS) patients, the doses used in trials were higher than doses used in practice, and recent data do not support an advantage of higher doses. We hypothesized that rates of major adverse cardiac events (MACE), all-cause death, myocardial infarction, and stroke are equivalent for patients on low-dose and high-dose ß-blocker. METHODS: Patients admitted to Intermountain Healthcare with ACS and diagnosed with ≥70% coronary stenosis between 1994 and 2013 were studied (N = 7,834). We classified low dose as ≤25% and high dose as ≥50% of an equivalent daily dose of 200 mg of metoprolol. Multivariate analyses were used to test association between low-dose versus high-dose ß-blocker dosage and MACE at 0-6 months and 6-24 months. RESULTS: A total of 5,287 ACS subjects were discharged on ß-blockers (87% low dose, 12% high dose, and 1% intermediate dose). The 6-month MACE outcomes rates for the ß-blocker dosage (low versus high) were not equivalent (P = .18) (hazard ratio [HR] = 0.76; 95% CI, 0.52-1.10). However, subjects on low-dose ß-blocker therapy did have a significantly decreased risk of myocardial infarction for 0-6 months (HR = 0.53; 95% CI, 0.33-0.86). The rates of MACE events during the 6-24 months after presentation with ACS were equivalent for the 2 doses (P = .009; HR = 1.03 [95% CI, 0.70-1.50]). CONCLUSIONS: In ACS patients, rates of MACE for high-dose and low-dose ß-blocker doses are similar. These findings question the importance of achieving a high dose of ß-blocker in ACS patients and highlight the need for further investigation of this clinical question.

Coronary Computed Tomography Angiography for Screening in Patients with Diabetes: Can Enhanced Detection of Subclinical Coronary Atherosclerosis Improve Outcome?

PURPOSE OF REVIEW: It is well known that there is a very high risk of cardiovascular complications among diabetic patients. In spite of all efforts at aggressive control of diabetes and its complications, the incidence of cardiovascular morbidity and mortality remains high, including in patients with no prior symptoms, underscoring a possible advantage for appropriate screening of asymptomatic patients for the presence of obstructive coronary artery disease (CAD). In this article, we sought primarily to review the results of studies designed to evaluate a possible role of coronary computed tomography angiography (CCTA) in the screening of asymptomatic diabetic patients for possible obstructive CAD. RECENT FINDINGS: Our review of current literature indicates that there is still no method of CAD screening identified that has been shown to reduce the cardiovascular risk of asymptomatic diabetic patients. Therefore, the utility and value of screening for CAD in asymptomatic diabetic patients remains controversial. CCTA screening has shown promise and has been demonstrated to predict future risk, but as yet has not demonstrated improvement in the outcomes of these high-risk patients. At our present state of knowledge, aggressive risk factor reduction appears to be the most important primary prevention strategy for all asymptomatic high-risk diabetic patients. However, there remains a great need for better and more sensitive and specific screening methods, as well as more effective treatments that may allow us to more accurately target diabetic patients who really are at high risk. Further large randomized and well-controlled clinical trials may be necessary to determine whether screening for CAD can reduce cardiovascular event rates in patients with diabetes.

Smartphone ECG for evaluation of STEMI: results of the ST LEUIS Pilot Study.

BACKGROUND: 12-lead ECG is a critical component of initial evaluation of cardiac ischemia, but has traditionally been limited to large, dedicated equipment in medical care environments. Smartphones provide a potential alternative platform for the extension of ECG to new care settings and to improve timeliness of care. OBJECTIVE: To gain experience with smartphone electrocardiography prior to designing a larger multicenter study evaluating standard 12-lead ECG compared to smartphone ECG. METHODS: 6 patients for whom the hospital STEMI protocol was activated were evaluated with traditional 12-lead ECG followed immediately by a smartphone ECG using right (VnR) and left (VnL) limb leads for precordial grounding. The AliveCor™ Heart Monitor was utilized for this study. All tracings were taken prior to catheterization or immediately after revascularization while still in the catheterization laboratory. RESULTS: The smartphone ECG had excellent correlation with the gold standard 12-lead ECG in all patients. Four out of six tracings were judged to meet STEMI criteria on both modalities as determined by three experienced cardiologists, and in the remaining two, consensus indicated a non-STEMI ECG diagnosis. No significant difference was noted between VnR and VnL. CONCLUSIONS: Smartphone based electrocardiography is a promising, developing technology intended to increase availability and speed of electrocardiographic evaluation. This study confirmed the potential of a smartphone ECG for evaluation of acute ischemia and the feasibility of studying this technology further to define the diagnostic accuracy, limitations and appropriate use of this new technology.

Usefulness of high-sensitivity C-reactive protein in predicting long-term risk of death or acute myocardial infarction in patients with unstable or stable angina pectoris or acute myocardial infarction.

High-sensitivity C-reactive protein (CRP), proposed as a new coronary risk marker, may reflect either an acute phase reaction or the level of chronic inflammation. Thus, CRP may be less predictive of long-term outcomes when measured after acute myocardial infarction (AMI) than after unstable angina pectoris (UAP) or stable angina pectoris (SAP). A total of 1,360 patients with severe coronary artery disease (>/=1 stenosis >/=70%) had CRP levels obtained at angiography. Presenting diagnoses were SAP (n = 599), UAP (n = 442), or AMI (n = 319). During follow-up (mean 2.8 years), death or nonfatal AMI (D/AMI) occurred in 19.5%, 16.1%, and 17.2% (p = NS) with SAP, UAP, and AMI, respectively. Corresponding median CRP levels were 1.31, 1.27, and 2.50 mg/dl (p <0.001). For the overall cohort, increasing age, low ejection fraction, revascularization, and elevated CRP were the strongest of 6 independent predictors for D/AMI. Among those presenting with SAP, CRP levels above the first tertile were associated with an adjusted hazard ratio of 1.8 (95% confidence interval [CI] 1.2 to 2.8, p <0.009) for D/AMI. After UAP, the hazard ratio was 2.7 (95% CI 1.4 to 5.0, p <0.002). However, when measured during hospitalization for AMI, CRP was not predictive of long-term outcome (hazard ratio 1.0 [95 % CI 0.5 to 1.7] p = 0.86). In conclusion, predischarge CRP levels are higher after AMI than after UAP or SAP. However, whereas CRP is strongly predictive of long-term D/AMI for patients presenting with SAP or UAP, it is not predictive shortly after AMI, suggesting that measurements should be delayed until the acute phase reaction is over and levels have returned to baseline.