Angiographic prevalence and clinical predictors of left subclavian stenosis in patients undergoing diagnostic cardiac catheterization.

The angiographic prevalence, clinical predictors, and sensitivity and specificity of a bilateral arm blood pressure differential for predicting proximal left subclavian artery stenosis were established in 492 patients undergoing cardiac catheterization. Seventeen subjects (3.5%) in the overall population and nine subjects (5.3%) with potential surgical coronary disease had proximal left subclavian stenosis. Precatheterization evidence of peripheral vascular disease (PVD) was the only predictor of subclavian stenosis in the overall population (P < 0.001; OR = 7.9; 95% CI = 2.6-24.3) and in patients with potential surgical coronary disease (P = 0.04; OR = 5.4; 95% CI = 1.1-27.2). Both a bilateral blood pressure differential of > 10 mm Hg and of > or =20 mm Hg had a good specificity but a poor sensitivity for predicting left subclavian stenosis. Thus, left subclavian angiography should be performed in patients with surgical coronary disease with either an arm blood pressure differential of > 10 mm Hg or with other precatheterization evidence of PVD. Cathet Cardiovasc Intervent 2001;54:8-11.

Patient selection reduces thrombotic complications of emergent stenting for failed PTCA.

A comparison of consecutive initial and later patients receiving emergent coronary artery stents to salvage failed PTCA procedures was made to determine whether experience with this procedure can improve patient outcome. Twenty-six consecutive patients underwent emergent, unplanned implantation of one or more Palmaz-Schatz coronary stents at our institution over a 3-1/2 year period. Indications for stent insertion included impending vessel closure (decrease in TIMI flow grade and clinical evidence of ischemia) or acute occlusion (TIMI flow grade 0 or 1 and > or = 99% stenosis) after PTCA. Immediate and final success (30 day) were determined, and the results in the first (Initial) 13 patients were compared to the remaining (Later) 13 patients. Baseline characteristics of the study population included a male predominance (69%) with a mean (+/- SD) age of 57 +/- 10 years. Conventional balloon PTCA was performed in all three native coronary arteries with an increase in mean percentage stenosis from 76 +/- 13 to 85 +/- 14% (P < 0.05). Twelve patients developed acute occlusion and 14 patients impending closure after PTCA due to the appearance of thrombus (12%), dissection (46%), or both (35%). Palmaz-Schatz stents were successfully inserted in all patients restoring TIMI grade 3 antegrade flow; however, major complications developed in almost 50% of patients. Comparison of initial and later patients showed no differences in demographic or pre-PTCA angiographic characteristics. Later patients had less severe stenoses post-PTCA (before stenting) and were less likely to have thrombus present at the angioplasty site (15% vs. 77%, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transluminal coronary angioplasty in patients undergoing chronic dialysis.

Very limited data on percutaneous transluminal coronary angioplasty in patients with chronic renal failure is available. We describe the short- and long-term results of percutaneous transluminal coronary angioplasty (PTCA) in a group of seven patients undergoing chronic dialysis. Percutaneous transluminal coronary angioplasty was undertaken because of poorly controlled symptoms in five patients and reversible defects on thallium scintigraphy prior to major surgery in two patients. There were five men and two women, the mean age was 51 years (range 36-75). Six patients were on hemodialysis and one was receiving peritoneal dialysis. All seven patients had complicated baseline coronary stenosis morphology ( greater than or equal to AHA/ACC Class B-1). Percutaneous transluminal coronary angioplasty was successful in four patients (57%) and associated with complications in two patients (29%) including one death. Surviving patients were followed for a mean of 6 months (range 3-23 months). Of three surviving patients with initially successful PTCA, two developed restenosis. All three patients with unsuccessful PTCA underwent bypass surgery with one late death. Patients with chronic renal failure compose a high risk population for PTCA with a reduced success rate, an increased complication rate, and a high restenosis rate.

The signal-averaged P wave duration: a rapid and noninvasive marker of risk of atrial fibrillation.

OBJECTIVES: This study was undertaken to determine the ability of the signal-averaged electrocardiogram (ECG) to identify evidence of delayed atrial activation in patients with a history of atrial fibrillation. BACKGROUND: Atrial fibrillation is a reentrant rhythm and depends on atrial conduction delay for its development. The signal-averaging technique is useful for accurately measuring total cardiac activation times, including delayed low amplitude signals, and thus can help identify the substrate for reentrant arrhythmias. METHODS: Standard 12-lead and signal-averaged ECGs were recorded from 15 patients with a documented history of prior paroxysmal or chronic atrial fibrillation and 15 age- and disease-matched control subjects without a history of atrial fibrillation. Signal averaging was performed using an orthogonal lead system with the QRS complex as a trigger and the P wave as a template for the signal-averaging process. Total P wave duration was measured before and after filtering with a least squares fit filter. The P wave complexes on the three bipolar leads were combined into a vector combination of orthogonal leads. The total P wave duration of the individual unfiltered and filtered leads and the vector combination of filtered leads were calculated and used for analysis. RESULTS: The P wave duration by standard ECG was not significantly different in patients with a history of atrial fibrillation and control subjects. Signal-averaged P wave durations were measured from orthogonal leads before and after digital filtering. Mean unfiltered P wave duration was significantly longer in patients with a history of atrial fibrillation than in control subjects (132 +/- 22 vs. 114 +/- 14 ms [p < 0.03] in the X lead, 135 +/- 21 vs. 115 +/- 15 ms [p < 0.03] in the Y lead and 133 +/- 23 vs. 114 +/- 14 ms [p < 0.03] in the Z lead). Mean filtered P wave duration was also longer in patients with atrial fibrillation than in control subjects (151 +/- 23 vs. 130 +/- 19 ms [p < 0.01] in the X lead, 157 +/- 22 vs. 136 +/- 17 ms [p < 0.01] in the Y lead and 154 +/- 23 vs. 135 +/- 15 ms [p < 0.01] in the Z lead). After filtering, a vector composite of orthogonal leads was determined. Again, P wave duration in patients with a history of atrial fibrillation exceeded that in the control subjects (162 +/- 15 vs. 140 +/- 12 ms [p < 0.01]). Using the vector composite of filtered orthogonal leads, a P wave duration > or = 155 ms was associated with a sensitivity of 80%, a specificity of 93% and a positive predictive value of 92% for identifying patients with history of atrial fibrillation. CONCLUSIONS: A prolonged signal-averaged P wave duration may be a simple noninvasive marker of the risk for development of atrial fibrillation.