Medical Management and Diagnostic Testing among Stable Angina Patients in India: The STable Angina obseRvational (STAR) Registry.

OBJECTIVE: To study the practice pattern in the management of patients with stable angina (SA) in India. METHODS: The Stable Angina obseRvational Registry (STAR) prospectively enrolled patients provisionally diagnosed with SA by non-interventional practicing internists in India. Patients were followed for 3 months after enrollment to assess medical treatment, diagnostic management, and interventional treatment of coronary artery disease (CAD). At the study conclusion, a statistical analysis retrospectively categorized patients not at risk of CAD by the Morise-Jalisi scale though this was not part of the study protocol. RESULTS: Between January and May 2012, 2079 patients were enrolled at 131 centres. Mean age was 57 ± 11 years, 62% were men, and 40% had a history of diabetes. Over 90% of patients completed follow-up visit, >85% received statins and antiplatelet medications, >70% received beta blockers, and >60% received angiotensin-converting-enzyme inhibitors or angiotensin receptor blockers. Diagnostic testing rates were low: 93% for electrocardiogram, 44% echocardiogram, 42% chest radiography, 12% stress test, and 8% underwent noninvasive CT or invasive coronary angiography, of which, 86% had abnormal results. After the study, the Morise-Jalisi probability of CAD was intermediate in 42% and high in 51% of patients. Only 3.4% of all patients had coronary revascularization. CONCLUSIONS: In a large cohort of Indian patients with SA, disease severity and probability of CAD were high. Clinicians used evidence-based care for medical management, but underutilized diagnostic testing. Patients with SA in India need to be risk-stratified for probability and severity of CAD and, if indicated, receive additional diagnostic testing.

Diagnosis of high-voltage conductor fractures in Sprint Fidelis leads.

BACKGROUND: Fractures of pace/sense conductors in implantable cardioverter-defibrillator (ICD) leads have been studied extensively, but little is known about fractures of high-voltage (HV) conductors. OBJECTIVE: To characterize the presentation of isolated HV conductor fractures, define the optimal impedance threshold for identifying them, and compare it to the existing nominal impedance threshold (200 Ω) for patient and remote-monitoring alerts. METHODS: This retrospective study analyzed HV fractures in explanted, dual-coil, model 6949 Sprint Fidelis leads (Medtronic, Minneapolis, MN). The study group consisted of 25 leads with structurally and electrically confirmed HV conductor fractures; 41 leads that were structurally and electrically intact served as controls. We analyzed long-term HV impedance trends from stored ICD data files of both groups to determine the optimal impedance threshold that would discriminate fractures from normal leads. RESULTS: In the study group, 14 leads (56%) had fractures of the cable to the right ventricular coil, 9 (36 %) leads had fractures of the cable to the superior vena cava (SVC) coil, and 2 (8%) had both. We found that an impedance threshold of >100 Ω and/or an abrupt 75% increase in chronic HV impedance were diagnostic of HV conductor fractures with 100% sensitivity and specificity. HV fractures proximal to the SVC coil were more likely to be associated with concomitant pace/sense fractures. Large (200 Ω to infinity), abrupt increases in impedance were more common when fractures occurred proximal to the right ventricular coil but distal to the SVC coil. CONCLUSIONS: HV conductor fractures can be diagnosed when HV impedance exceeds 100 Ω or abruptly increases by 75% from baseline.

Preventing overdiagnosis of implantable cardioverter-defibrillator lead fractures using device diagnostics.

OBJECTIVES: This study sought to use implantable cardioverter-defibrillator (ICD) diagnostics to discriminate ICD lead fractures from normally functioning leads with high impedance and from connection problems between the lead and header. BACKGROUND: ICD diagnostics facilitate identification of fractures, but there are no accepted criteria for discriminating fractures from other causes of high impedance and/or nonphysiological "noise" oversensing. METHODS: We analyzed a development set of 91 leads to construct a stepwise algorithm based on ICD diagnostics. It included 40 fractures, 30 connection problems, and 21 functioning leads that triggered high-impedance alerts. Then we applied this algorithm to an independent test set of 100 leads: 70 fractures and 30 intact leads with connection problems that were misdiagnosed clinically as fractures. In the algorithm, either extremely high maximum impedance or noise oversensing with a normal impedance trend indicated a fracture. A short interval from surgery to impedance rise or prolonged stable impedance after an abrupt rise indicated a connection problem. A gradual impedance increase or stable, high impedance indicated a functioning lead. RESULTS: In the test set, the algorithm correctly classified 100% of fractures (95% confidence interval [CI]: 95% to 100%) and 87% of connection problems that were misdiagnosed as fractures (95% CI: 70% to 95%). CONCLUSIONS: An algorithm using only ICD diagnostics identifies leads with oversensing or high impedance as fractures or connection problems with a high degree of accuracy.

Downloadable software algorithm reduces inappropriate shocks caused by implantable cardioverter-defibrillator lead fractures: a prospective study.

BACKGROUND: Downloadable software upgrades are common in consumer electronics but not in implantable medical devices. Fractures of implantable cardioverter-defibrillator (ICD) leads present commonly as inappropriate shocks. A lead-integrity alert (LIA) designed to reduce inappropriate shocks is the first software download approved to enhance nominally functioning, previously implanted ICDs. METHODS AND RESULTS: We performed a prospective study to determine whether an LIA could reduce inappropriate shocks. Patients were included if they had ICD lead fractures confirmed by analysis of explanted leads. The LIA group included the first 213 patients who met the inclusion criteria after the LIA was approved who had the LIA downloaded. The LIA is triggered either by high impedance or rapid oversensing. It responds by delaying detection of ventricular fibrillation and initiating a patient alert every 4 hours. The control group included the first 213 patients who did not have the LIA downloaded. They were monitored by conventional daily impedance measurements that respond with a daily alert. The LIA group had a 46% relative reduction (95% confidence interval 34% to 55%) in the percentage of patients with ≥1 inappropriate shock (LIA 38% versus control 70%, P<0.001) and a 50% relative reduction (95% confidence interval 33% to 61%) in the percentage with ≥5 shocks (25% versus 50%, P<0.001). The LIA group also had a higher percentage of patients who either did not receive a shock or had ≥3 days of warning before the shock (72% versus 50%, P<0.001). CONCLUSIONS: A software download that upgrades previously implanted ICDs without surgical revision reduces inappropriate shocks caused by lead fractures.