Faculty Bibliography

BACKGROUND: Studies demonstrate an increase in radiation exposure with transradial approach (TRA) when compared with transfemoral approach (TFA) for coronary angiography. Given the learning curve associated with TRA, it is not known if this increased radiation exposure to patients is seen when procedures are performed by experienced operators. METHODS: We retrospectively evaluated 1,696 patients who underwent coronary angiography with or without percutaneous coronary intervention (PCI) by experienced operators at a tertiary center from October 2010 to June 2011. Experienced operators were defined as those that perform >75 PCIs/year with >95% of cases performed using the TRA or TFA approach for >/=5 years. The outcomes of interest were dose area product (DAP) and fluoroscopy time (FT). RESULTS: Of the 1,696 patients, 1,382 (81.5%) were performed by experienced femoral operators using TFA and 314 (18.5%) were performed by experienced radial operators using TRA. Most of these cases (65.4%) were diagnostic only (870 TFA and 240 TRA) with both DAP (6040 [3210-8786] vs 5019 [3377-6869] muGy.m, P = .003] and FT [6.2 [4.0-10.3] vs 3.3 [2.6-5.0] minutes, P < .001) significantly higher using TRA versus TFA. For procedures involving PCI, despite similar baseline patient, procedural and lesion characteristics, DAP and FT remained significantly higher using TRA versus TFA (19,649 [11,996-25,929] vs 15,395 [10,078-21,617] muGy.m, P = .02 and 22.1 [13.3-31.0] vs. 13.8 [9.8-20.3] minutes, P < .001). CONCLUSIONS: In a contemporary cohort of patients undergoing coronary angiography by experienced operators, TRA was associated with higher radiation exposure when compared with TFA.

BACKGROUND: Contemporary studies have shown that spontaneous but not procedural myocardial infarction (MI) are related to subsequent mortality. Whether PCI reduces spontaneous (non-procedural) MI is unknown. METHODS AND RESULTS: PUBMED, EMBASE, and CENTRAL were searched for randomized clinical trials (RCTs), until October 2012, comparing PCI with OMT, for stable ischemic heart disease, and reporting MI outcomes - spontaneous non-procedural MI, procedural MI and all MI including procedure related MI. Given the varying length of follow-up between trials, a mixed-effect poisson regression meta-analysis was employed. From 12 RCTs with 37548 patient-years of follow-up, PCI, when compared with OMT alone, was associated with significant lower incident rate ratio (IRR) for spontaneous non-procedural MI (IRR=0.76, 95% CI 0.58-0.99) at the risk of higher procedural MI (IRR=4.11, 95% CI 2.53-6.88) without any difference in all MI (IRR=0.96, 95% CI 0.74-1.21). The point estimate for PCI vs. OMT for all-cause mortality (IRR=0.88, 95% CI 0.75-1.03) and cardiovascular mortality (IRR=0.70, 95% CI 0.44-1.09) paralleled that of spontaneous non-procedural MI (but not procedural or all nonfatal MI) although these were not statistically significant. CONCLUSIONS: PCI compared to OMT reduced spontaneous MI at the risk of procedural MI without any difference in all MI. Consistent with prior studies showing that spontaneous MI but not procedural MI are related to subsequent mortality, in the present report the point estimate for reduced mortality with PCI compared to OMT paralleled the prevention of spontaneous MI with PCI. Further studies are needed to determine whether these associations are causal.

OPINION STATEMENT: Elevated resting heart rate is an independent risk factor for cardiovascular morbidity and mortality in patients with and without coronary artery disease. In patients with known coronary artery disease, elevated heart rate reduces diastolic filling time and increases cardiac workload, resulting in supply demand mismatch with consequent ischemia and angina. While lower heart rate is associated with better prognosis, it is not known if pharmacological reduction in heart rate is beneficial and if heart rate is merely a marker for increased risk and worse outcomes. Certainly, physiologically lower resting heart rate as attained by exercise improves morbidity and mortality. While physiological reduction in heart rate is mainly a manifestation of increased parasympathetic drive, pharmacological reduction of heart rate with beta-blockers is mediated via the sympathetic pathway and associated with mixed outcomes. In addition, beta-blockers have other cardiovascular effects (lowering blood pressure), are metabolically active, and it is unknown if the beneficial effects (if any) are mediated via reduction in heart rate versus other cardiovascular effects. Ivabradine is a new medication that lowers heart rate selectively by inhibiting the I(f) current without other cardiovascular effects, offering for the first time a therapeutic agent that selectively targets heart rate. The medication has shown promise in early trials in patients with heart failure, but it is unclear if this agent will be beneficial in patients with stable coronary artery disease without heart failure.