Coronary artery disease risk reclassification by a new acoustic-based score.

To determine the potential of a non-invasive acoustic device (CADScor®System) to reclassify patients with intermediate pre-test probability (PTP) and clinically suspected stable coronary artery disease (CAD) into a low probability group thereby ruling out significant CAD. Audio recordings and clinical data from three studies were collected in a single database. In all studies, patients with a coronary CT angiography indicating CAD were referred to coronary angiography. Audio recordings of heart sounds were processed to construct a CAD-score. PTP was calculated using the updated Diamond-Forrester score and patients were classified according to the current ESC guidelines for stable CAD: low < 15%, intermediate 15-85% and high > 85% PTP. Intermediate PTP patients were re-classified to low probability if the CAD-score was ≤ 20. Of 2245 patients, 212 (9.4%) had significant CAD confirmed by coronary angiography ( ≥ 50% diameter stenosis). The average CAD-score was higher in patients with significant CAD (38.4 ± 13.9) compared to the remaining patients (25.1 ± 13.8; p < 0.001). The reclassification increased the proportion of low PTP patients from 13.6% to 41.8%, reducing the proportion of intermediate PTP patients from 83.4% to 55.2%. Before reclassification 7 (3.1%) low PTP patients had CAD, whereas post-reclassification this number increased to 28 (4.0%) (p = 0.52). The net reclassification index was 0.209. Utilization of a low-cost acoustic device in patients with intermediate PTP could potentially reduce the number of patients referred for further testing, without a significant increase in the false negative rate, and thus improve the cost-effectiveness for patients with suspected stable CAD.

Segmentation of heart sound recordings by a duration-dependent hidden Markov model.

Digital stethoscopes offer new opportunities for computerized analysis of heart sounds. Segmentation of heart sound recordings into periods related to the first and second heart sound (S1 and S2) is fundamental in the analysis process. However, segmentation of heart sounds recorded with handheld stethoscopes in clinical environments is often complicated by background noise. A duration-dependent hidden Markov model (DHMM) is proposed for robust segmentation of heart sounds. The DHMM identifies the most likely sequence of physiological heart sounds, based on duration of the events, the amplitude of the signal envelope and a predefined model structure. The DHMM model was developed and tested with heart sounds recorded bedside with a commercially available handheld stethoscope from a population of patients referred for coronary arterioangiography. The DHMM identified 890 S1 and S2 sounds out of 901 which corresponds to 98.8% (CI: 97.8-99.3%) sensitivity in 73 test patients and 13 misplaced sounds out of 903 identified sounds which corresponds to 98.6% (CI: 97.6-99.1%) positive predictivity. These results indicate that the DHMM is an appropriate model of the heart cycle and suitable for segmentation of clinically recorded heart sounds.

Bilateral internal thoracic artery operations in the elderly.

BACKGROUND: Elderly surgical patients have higher operative morbidity and mortality than younger cohorts, particularly when the procedure is lengthy and complex. While use of bilateral internal thoracic arteries (BITA) is often associated with increased surgical risk, we nevertheless hypothesized that the use of BITA in elderly coronary artery bypass patients would not significantly increase their operative risk beyond that encountered using single internal thoracic arterial (SITA) or saphenous vein grafts (SVG). We maintained that arterial grafts remain essentially unaffected by arteriosclerosis, and that extension of a high-quality life is a desirable outcome regardless of age at operation. EXPERIMENTAL DESIGN: We studied myocardial revascularization in 673 patients over 65 years of age at the time of operation. All operations were conducted or supervised by a single surgeon during a ten-year period from January 1986 to January 1996. Preoperative and operative dates were recorded prospectively. SETTING: All patients underwent coronary artery bypass grafting. INTERVENTIONS: The study compared outcomes in patients having all veins, SITA or BITA operations. For the first analysis, 673 patients were divided into three groups: 163 patients (Group 1) had saphenous vein used for all bypasses; 338 patients had a SITA with supplemental vein grafts (Group 2); and 172 patients (Group 3) had BITAs with additional vein grafts as needed. In the second analysis, Group 3 was subdivided and grouped by the coronary arteries which received the ITA grafts, and the analysis was repeated. One hundred and sixteen patients (Group 3A) underwent traditional placement of ITA bypasses (left ITA to the LAD, right ITA to the RCA); in Group 3B, 56 patients received revascularization of branches of the left coronary artery (left ITA to the circumflex system, right ITA to the LAD). MEASURES: We communicated directly with 90.5% of the patients, their families, or their physicians. The survival status of the remainder was determined through the National Social Security Death Index Network. This allowed us to obtain follow-up longevity data for 100% of the study sample at a mean observation period of 5.03+/-3.1 years with variation between 10.8 years to 2.4 years. RESULTS: A multivariate analysis showed that placement of both ITA grafts to left-sided arteries in older patients independently improved long-term survival (p=0.031). CONCLUSIONS: The BITA procedure does not have greater operative morbidity or mortality in the elderly despite the length or complexity of the surgery. To realize improved long-term survival rates, however, both ITAs must be grafted to the left coronary artery branches.