Scientific STAFF and MALT meetings - past, present, and future.

The scientific STAFF and MALT meetings were created around the turn of the century for scientists engaged in enhancing the role of the 12-lead ECG for detection and quantification of involved myocardium in patients with acute coronary syndrome. These meetings were initially focused on computer processing of data from two single-center databases. The STAFF database was collected in the mid-nineties on patients with prolonged total coronary occlusion; high-resolution 12-lead ECGs were collected before, during, and after 5 minutes of occlusion. The MALT database was created in the early years of this century on consecutive patients with chest pain admitted to a large teaching hospital. Delayed enhancement magnetic resonance imaging and electrocardiograms were recorded in these acutely ill patients. The paper highlights the first 2 decades of the STAFF and MALT meetings and details the meeting format.

An electrocardiographic sign of ischemic preconditioning.

Ischemic preconditioning is a form of intrinsic cardioprotection where an episode of sublethal ischemia protects against subsequent episodes of ischemia. Identifying a clinical biomarker of preconditioning could have important clinical implications, and prior work has focused on the electrocardiographic ST segment. However, the electrophysiology biomarker of preconditioning is increased action potential duration (APD) shortening with subsequent ischemic episodes, and APD shortening should primarily alter the T wave, not the ST segment. We translated findings from simulations to canine to patient models of preconditioning to test the hypothesis that the combination of increased [delta (Δ)] T wave amplitude with decreased ST segment elevation characterizes preconditioning. In simulations, decreased APD caused increased T wave amplitude with minimal ST segment elevation. In contrast, decreased action potential amplitude increased ST segment elevation significantly. In a canine model of preconditioning (9 mongrel dogs undergoing 4 ischemia-reperfusion episodes), ST segment amplitude increased more than T wave amplitude during the first ischemic episode [ΔT/ΔST slope = 0.81, 95% confidence interval (CI) 0.46-1.15]; however, during subsequent ischemic episodes the T wave increased significantly more than the ST segment (ΔT/ΔST slope = 2.43, CI 2.07-2.80) (P < 0.001 for interaction of occlusions 2 vs. 1). A similar result was observed in patients (9 patients undergoing 2 consecutive prolonged occlusions during elective percutaneous coronary intervention), with an increase in slope of ΔT/ΔST of 0.13 (CI -0.15 to 0.42) in the first occlusion to 1.02 (CI 0.31-1.73) in the second occlusion (P = 0.02). This integrated analysis of the T wave and ST segment goes beyond the standard approach to only analyze ST elevation, and detects cellular electrophysiology changes of preconditioning.

The STAFF studies of the first 5 minutes of percutaneous coronary angioplasty balloon occlusion in man.

The Staff Studies comprise a database of 228 patients undergoing elective 5 minute coronary artery balloon occlusion angioplasty at a single center in the pre-stent era in whom standard and high-frequency electrocardiographic and nuclear information was obtained immediately before, during and after balloon occlusion. The data were then analyzed by multiple investigators at different international academic centers from different perspectives. Simulating in a clinical setting the first 5 minutes of a heart attack, this database, now in digital format, is the largest database to date documenting standard and high-frequency ECG changes from the onset and for 5 minutes during acute coronary artery occlusion, with resting and occlusion imaging in a subset of these patients. The history, methodology, and legacy of these studies are discussed in this paper.

Difference vectors to describe dynamics of the ST segment and the ventricular gradient in acute ischemia.

BACKGROUND: The ECG is important in the diagnosis and triage of the acute coronary syndrome (ACS), especially in the hyperacute phase, the "golden hours," during which myocardial salvage possibilities are largest. An important triaging decision to be taken is whether or not a patient requires primary PCI, for which, as mentioned in the guidelines, the presence of an ST elevation (STE) pattern in the ECG is a major criterion. However, preexisting non-zero ST amplitudes (diagnostic, but also non-diagnostic) can obscure or even preclude this diagnosis. METHODS: In this study, we investigated the potential diagnostic possibilities of ischemia detection by means of changes in the ST vector, ΔST, and changes in the VG (QRST integral) vector, ΔVG. We studied the vectorcardiograms (VCGs) synthesized of the ECGs of 84 patients who underwent elective PTCA. Mean±SD balloon occlusion times were 260±76s. The ECG ischemia diagnosis (ST elevation, STE, or non-ST-elevation, NSTE), magnitudes and orientations of the ST and VG vectors, and the differences ΔST and ΔVG with the baseline ECG were measured after 3min of balloon occlusion. RESULTS: Planar angles between the ΔST and ΔVG vectors were 14.9±14.0°. Linear regression of ΔVG on ΔST yielded ΔVG=324·ΔST (r=0.85; P<0.0001, ΔST in mV). We adopted ΔST>0.05mV, and the corresponding ΔVG>16.2mV·ms as ischemia thresholds. The classical criteria characterized the ECGs of 46/84 (55%) patients after 3min of occlusion as STE ECGs. Combined application of the ΔST and ΔVG criteria identified 73/84 (87%) of the patients as ischemic. CONCLUSION: Differential diagnosis by ΔST and ΔVG (requiring an earlier made non-ischemic baseline ECG) could dramatically improve ECG guided detection of patients who urgently require catheter intervention.

Assessment of autonomic control of the heart during transient myocardial ischemia.

INTRODUCTION: In the presence of coronary artery obstruction, complex cardiovascular reflexes may lead to changes in heart rate and even to the precipitation of malignant arrhythmias. The autonomic nervous system (ANS) has traditionally been considered to be "balanced" between continuously interacting sympathetic and parasympathetic outflows. The purpose of this study was to assess ANS control of the heart during prolonged coronary balloon occlusion procedures of one of the major coronary arteries. METHODS: R-R intervals were obtained from continuous electrocardiographic data of 90 patients undergoing selective percutaneous coronary interventions (PCI) with balloon inflation periods ranging from 3 to 10 minutes (4.7 ± 1.1 minutes). Three 3-minute stages were chosen: (1) preinflation (baseline), (2) from the start of occlusion (PCI), and (3) immediately post deflation. The dynamics of the ANS was evaluated by heart rate variability analysis using standard time and frequency domain indices and the short-term fractal-like index (α(1)). RESULTS: During PCI, time and frequency domain measures related to vagal control decreased significantly with respect to baseline (significantly in left anterior descending [LAD] artery occlusions). During the postdeflation stage, heart rate variability and high-frequency power increased (P < .01) in the group with right coronary artery occlusions, whereas a marked sympathetic increase, as assessed by an increase (P < .01) of normalized low-frequency power and the low/high-frequency ratio was observed in the LAD group after balloon deflation. Fractal index α(1) decreased during the PCI period but increased significantly after balloon deflation. CONCLUSIONS: Significant changes in autonomic control of heart rate that were a function of the affected artery occurred during and after coronary artery occlusions. Occlusion of the LAD resulted in a significant reduction of vagal activity and a decrease of the short-term fractal index during PCI and a marked sympathetic response after postdeflation. However, a marked increment of vagal activity between the occlusion stage and postdeflation period was found in the right coronary artery group. These results may relate the site of the occlusion and lack of blood supply to different parts of the left ventricle.

Accuracy of advanced versus strictly conventional 12-lead ECG for detection and screening of coronary artery disease, left ventricular hypertrophy and left ventricular systolic dysfunction.

BACKGROUND: Resting conventional 12-lead ECG has low sensitivity for detection of coronary artery disease (CAD) and left ventricular hypertrophy (LVH) and low positive predictive value (PPV) for prediction of left ventricular systolic dysfunction (LVSD). We hypothesized that a approximately 5-min resting 12-lead advanced ECG test ("A-ECG") that combined results from both the advanced and conventional ECG could more accurately screen for these conditions than strictly conventional ECG. METHODS: Results from nearly every conventional and advanced resting ECG parameter known from the literature to have diagnostic or predictive value were first retrospectively evaluated in 418 healthy controls and 290 patients with imaging-proven CAD, LVH and/or LVSD. Each ECG parameter was examined for potential inclusion within multi-parameter A-ECG scores derived from multivariate regression models that were designed to optimally screen for disease in general or LVSD in particular. The performance of the best retrospectively-validated A-ECG scores was then compared against that of optimized pooled criteria from the strictly conventional ECG in a test set of 315 additional individuals. RESULTS: Compared to optimized pooled criteria from the strictly conventional ECG, a 7-parameter A-ECG score validated in the training set increased the sensitivity of resting ECG for identifying disease in the test set from 78% (72-84%) to 92% (88-96%) (P < 0.0001) while also increasing specificity from 85% (77-91%) to 94% (88-98%) (P < 0.05). In diseased patients, another 5-parameter A-ECG score increased the PPV of ECG for LVSD from 53% (41-65%) to 92% (78-98%) (P < 0.0001) without compromising related negative predictive value. CONCLUSION: Resting 12-lead A-ECG scoring is more accurate than strictly conventional ECG in screening for CAD, LVH and LVSD.

Comparison of high-frequency QRS components and ST-segment elevation to detect and quantify acute myocardial ischemia.

OBJECTIVE: This study tests the ability of high-frequency components of the depolarization phase (HF-QRS) vs conventional ST-elevation criteria to detect and quantify myocardial ischemia. METHODS: Twenty-one patients admitted for elective percutaneous coronary intervention were included. Quantification of the ischemia was made by myocardial scintigraphy. High-resolution electrocardiogram before and during percutaneous coronary intervention was recorded and signal averaged. The HF-QRS were determined within the frequency band 150 to 250 Hz. ST-segment deviation was measured in the standard frequency range (<100 Hz). RESULTS: HF-QRS criteria were met by 76% of the patients, whereas 38% met the ST-elevation criteria (P = .008). Both HF-QRS reduction and ST elevation correlated significantly with the amount of ischemia (HF-QRS: r = 0.59, P = .005 for extent and r = 0.69, P = .001 for severity; ST elevation: r = 0.49, P = .023 for extent and r = 0.57, P = .007 for severity). CONCLUSIONS: This study suggests that HF-QRS analysis could provide valuable information both to detect acute ischemia and to quantify myocardial area at risk.

Redundant protective barriers: minimizing operator occupational risk.

BACKGROUND: The ubiquitous use of less invasive therapeutic angiographic procedures has created the milieu for long-term occupational risk of cancer and genetic defects. This study set out to determine the relative effectiveness of redundant radiation protective barriers and their impact on operator total-body-ionizing radiation exposure in the catheterization suite. METHODS: Thermolucent dosimeter x-irradiation was measured inside and outside personal and movable protective barriers used concurrently during 50 consecutive procedures by a single operator. Additionally, the entrance/exit doses were recorded on the back and chest for all patients to provide insight into radiation scatter patterns. RESULTS: The x-ray beam had an average 90.8% decrement in energy traversing the patient's chest when entrance and exit doses were compared, suggesting a 3.3-fold greater operator scatter radiation exposure below the table compared with that above the table. All 0.5-mm lead equivalent personal barriers reduced operator exposure by 72-95%, whereas the 1.0-mm leaded personal barrier (overlapping gown) reduced exposure by 96%. The 0.75-mm leaded glasses reduced exposure to the left eye by 67%. A leaded left-hand glove reduced exposure by only 20%. The effective calculated operator radiation exposure risk reduction provided by the use of personal and movable barriers reduced the theoretical risk of fatal or nonfatal cancer by 22-fold while decreasing potential severe genetic effect by 25-fold in comparison to movable barriers alone. CONCLUSIONS: The optimal use of combined personal and movable (redundant) lead barriers results in a significant reduction in total-body operator radiation exposure in the catheterization laboratory. The use of redundant barriers in the catheterization suite is associated with a dramatic theoretical long-term occupational risk reduction and should be encouraged.

Detection of stress-induced myocardial ischemia from the depolarization phase of the cardiac cycle--a preliminary study.

BACKGROUND: Electrocardiogram (ECG)-based detection of ischemia is typically dependent on identifying changes in repolarization. Analysis of high-frequency QRS (HFQRS) components, related to the depolarization phase of the cardiac action potential, has been reported to better identify ischemia. Our aim was to test the hypothesis that HFQRS analysis is both more sensitive and specific than standard ECG for detecting exercise-induced ischemia in patients undergoing exercise myocardial perfusion imaging (MPI). METHODS: Exercise MPI was performed in 133 consecutive patients (age, 63 +/- 12; 100 males) and used as the gold standard for ischemia. Patients with QRS duration more than 120 milliseconds (n = 20), technical problems (n = 8), or inconclusive MPI (n = 4) were excluded, leaving 101 patients for analysis. Conventional ECG was combined with high-resolution ECG acquisition that was digitized and analyzed using the HyperQ System (BSP, Tel Aviv, Israel). The relative HFQRS intensity change during exercise was used as an index of ischemia. RESULTS: Of the 101 patients who were included in the analysis, 19 exhibited MPI ischemia. The HFQRS index of ischemia was found to be more sensitive (79% vs 41%; P < .05) and more specific (71% vs 57%; P < .05) than conventional ST analysis. CONCLUSIONS: The HFQRS analysis was more sensitive and specific than conventional ECG interpretation in detecting exercise-induced ischemia and exhibited enhanced diagnostic performance in both women and men. Thus, it may aid in the noninvasive diagnosis of ischemic heart disease.

Nanobacteria-associated calcific aortic valve stenosis.

Calcific aortic valve stenosis is the most common valvular disease in developed countries, and the major reason for operative valve replacement. In the US, the current annual cost of this surgery is approximately 1 billion dollars. Despite increasing morbidity and mortality, little is known of the cellular basis of the calcifications, which occur in high-perfusion zones of the heart. The case is presented of a patient with calcific aortic valve stenosis and colonies of progressively mineralized nanobacteria in the fibrocalcific nodules of the aortic cusps, as revealed by transmission electron microscopy. Consistent with their outstanding bioadhesivity, nanobacteria might serve as causative agents in the development of calcific aortic valve stenosis.

Comparison of ST-segment deviation to scintigraphically quantified myocardial ischemia during acute coronary occlusion induced by percutaneous transluminal coronary angioplasty.

This study compared ST-segment changes during acute coronary artery occlusion with measurements of ischemia by myocardial scintigraphy. Forty patients who were referred for elective prolonged percutaneous transluminal coronary angioplasty underwent 12-lead electrocardiographic recording before the procedure (baseline) and continuously during the entire balloon inflation (occlusion). For each patient, the summed ST-segment deviation was calculated as the maximal absolute difference, elevation or depression, between baseline and occlusion recordings in all 12 leads. Each patient underwent 2 myocardial scintigraphies, 1 with technetium-99m sestamibi injected during the balloon inflation and 1 on the following day as a control study. Ischemia that was induced by balloon occlusion was quantified in terms of extent and severity. Results for the entire study group showed that summed ST deviation correlated with extent (r = 0.59, p < 0.0001) and severity (r = 0.61, p < 0.0001) of ischemia. The location of maximal ST deviation differed for the 3 arteries. For occlusion of the left anterior descending artery, maximal ST deviation was elevated in lead V3. For occlusion of the left circumflex artery, maximal ST deviation was depressed in lead V2. Occlusion of the right coronary artery caused ST elevation in lead III and ST depression in lead V2. In conclusion, this study demonstrated a significant correlation between summed ST deviation and myocardial ischemia during coronary occlusion that is induced by percutaneous transluminal coronary angioplasty.

High-frequency QRS electrocardiogram analysis during exercise stress testing for detecting ischemia.

INTRODUCTION: ECG stress testing is an inexpensive and non-invasive detector of myocardial ischemia; addition of high-frequency QRS analysis (HFQRS) may improve accuracy. This study compared HFQRS during exercise in patients with and without ischemia as defined by multiple criteria. MATERIAL AND METHODS: High-resolution ECGs were recorded for 139 patients undergoing T99-sestamibi/T201-thallium stress testing. Twenty-three were positive by at least two and 37 were negative for ischemia by all three of the following criteria: nuclear scan, ST-segment analysis and typical angina. Sixty-four not meeting criteria for positive or negative, six with adenosine test and nine patients with ECG recording artifacts were excluded. Mean age of the study group was 62+/-10 years, 83% were male. Ischemic patients had a higher incidence of previous myocardial infarction and coronary intervention than non-ischemic patients (74% vs. 46%; P=0.03 and 70% vs. 43%; P=0.05, respectively), but had a lower body mass index (28.7+/-5 vs. 33.0+/-8; P=0.015). HFQRS analysis consisting of signal averaging (150-250 Hz) and calculation of root mean squared values for each lead at different time points was performed and was similar between the groups. The relative change in HFQRS (RCQ) was calculated for each lead: {(maxHFQRS-minHFQRS)/maxHFQRS}. For each patient an RCQ index was calculated by averaging the two leads with the greatest RCQ value. The RCQ index was greater in ischemic vs. non-ischemic patients (45% vs. 34%; P=0.0069). CONCLUSION: Maximum decrease in HFQRS, as quantified by RCQ index, was greater in ischemic vs. non-ischemic patients. Use of the RCQ index may improve the diagnosis of ischemia during exercise stress testing.

Comprehensive hospital care improvement strategies reduce time to treatment in ST-elevation acute myocardial infarction.

BACKGROUND: Delay in treatment of patients with ST-elevation acute myocardial infarction (STEMI) has an adverse effect on patient outcomes. Limited data are available on the effectiveness of hospital care improvement strategies (HCIS) to reduce time to reperfusion by percutaneous coronary intervention (PCI). This study evaluated the combined effect of HCIS implementation to reduce door-to-balloon time in patients with STEMI. METHODS: Retrospective chart review was done for 95 consecutive patients with STEMI who underwent PCI at Charleston Area Medical Center. Patients with non-STEMI and patients transferred from other medical centers were excluded. Door-to-balloon time was defined as time from emergency department arrival to first PCI balloon inflation. A program of 3 HCIS was implemented: 1) a fast-track catheterization laboratory protocol, 2) feedback to cardiologists on their treatment times, and 3) a weekday 24-hour inhouse catheterization laboratory team. Patients were separated into groups before (n = 46), during (n = 18), and after (n = 31) HCIS implementation. RESULTS: Mean age was 60.3 +/- 13 years and 74% were male. The majority (64%) arrived by ambulance; 29% had a prehospital electrocardiogram done. Most patients presented during the day (68%) on weekdays (75%). Symptom onset-to-door time was 289 +/- 393 minutes. No significant differences were found between the groups for these variables. Door-to-PCI time in minutes was reduced in the group after versus the group before HCIS implementation (94.3 +/- 37 vs 133.5 +/- 53; P < 0.0001). CONCLUSION: Implementation of HCIS shortened door-to-PCI time for patients with STEMI by 39.2 +/- 10 minutes. Thus, HCIS may be effective in improving patient outcomes.