Utility of Per Vessel Coronary Artery Calcium (CAC) Score in Symptomatic Patients Undergoing Coronary Computed Tomography in Predicting Major Adverse Cardiovascular Events: Single Center Experience and Literature Review.

Background: Atherosclerotic vascular disease remains a significant etiology of morbidity and mortality in the United States. Coronary artery calcium (CAC) is associated with increased stroke incidence and coronary atherosclerotic burden. Uncertainty remains regarding how best to interpret non-zero CAC scores, particularly in symptomatic patients. Methods: A review of the first 1122 patients who underwent coronary CT angiography (CCTA) with CAC scoring from January 2005 until July 2012 was performed. Patients were dichotomized into 2 groups, zero CAC score and non-zero CAC score. Non-zero CAC patients were further subdivided based on the specific coronary artery containing calcium. Rates of major adverse cardiovascular events (MACE) defined as all-cause mortality, non-fatal myocardial infarction (MI), ischemic stroke, and late revascularization (>90 days following CCTA) were evaluated in each group. Results: 505 patients (63% male, mean age 60 ± 11) with non-zero CAC scores were analyzed over a six year period with resultant median follow up period of 22 months (IQR25,75 13-34 months). Major adverse cardiovascular events were observed in 11 patients. Receiver-operator curve (ROC) analysis on each coronary segment showed significance with the presence of left main (LM) CAC (AUC 0.752, p=0.004). Conclusions: The presence of CAC at any value in the LM in this case series appears to predispose patients to increased rates of MACE.

Temporal Trends in Radiation Exposure and Utilization of Coronary CT Angiography, SPECT, and Invasive Coronary Angiography.

Background: The use of noninvasive medical imaging has increased over the past decade at a cost of significant lifetime radiation exposure to study subjects. We report the implementation of radiation dose reduction methods and associated reduction in ionizing radiation exposure with Coronary Computed Tomography Angiography (CCTA) over time. Methods: Radiation doses and total number of studies performed were evaluated constantly from January 2010 to September 2012 for CCTA (N=2613), as well as Single photon emission computed tomography (SPECT, N=8060) part of an ongoing effort to minimize radiation exposure. Analysis of variance was used to evaluate the radiation exposure reduction among modalities. We compared CCTA radiation doses in the era of retrospective protocols coupled with dose modulation (40%-80%phase) using Siemens® 64-slice Dual Source technology, with prospective scanning on the same equipment, as well as radiation doses on the newer Siemens® Flash Equipment and the implementation of nursing/technologist aggressively driven protocol for heart rate control and image acquisition independent of imaging provider presence during acquisition. Results: The radiation dose reduction with implementation of multiple measures of radiation reduction to include physician independent-technician driven CCTA protocol resulted in a reduction from mean of 9.85±5.96 (median 8.8mSv) to mean of 3.00±2.53(median 2.1mSv) (p<0.0001). CCTA radiation dose has decreased by 69.2% since January of 2010 while SPECT radiation dose remained constant at 14mSv (p<0.0001). Conclusion: Continued advances in software and hardware technology, combined with “physician independent-technician driven” CCTA protocol have drastically reduced radiation dosing in CCTA to annual background radiation exposure, while maximizing the benefit of the study and without sacrificing patient safety.