Fahad Iqbal

Comparison of the Prognostic Value of Normal Regadenoson With Normal Adenosine Myocardial Perfusion Imaging With Propensity Score Matching

OBJECTIVES The aim of this study was to test the hypothesis that patients with normal regadenoson myocardial perfusion imaging (MPI) have a low rate of cardiac events, similar to patients with normal adenosine MPI. BACKGROUND Regadenoson, a new selective adenosine A(2A) receptor agonist, is now a widely used stress agent for MPI. The low rate of cardiac events in patients with normal adenosine MPI is well-documented, but the prognostic implications of a normal regadenoson MPI have not been examined and compared with those with adenosine. METHODS Data on primary composite endpoint (cardiac death, myocardial infarction, and coronary revascularization) were collected for 2,000 patients (1,000 regadenoson, and 1,000 adenosine stress) with normal myocardial perfusion and left ventricular ejection fraction referred for vasodilator MPI. In addition, propensity scores were used to assemble a balanced cohort of 505 pairs of patients who were balanced on 36 baseline characteristics. RESULTS The primary endpoint occurred in 21 (2.1%; 1.1%/year) patients in the regadenoson group and 33 (3.3%; 1.7%/year) patients in the adenosine group (hazard ratio [HR] for regadenoson vs. adenosine: 0.62; 95% confidence interval [CI]: 0.36 to 1.08; p = 0.090). In the propensity-matched pairs, the primary endpoint occurred in 7 (1.4%; 0.7%/year) patients in the regadenoson group and 13 (2.6%; 1.3%/year) patients in the adenosine group (matched HR: 0.58; 95% CI: 0.23 to 1.48; p = 0.257). Cardiac deaths were infrequent in the entire sample and in the propensity-matched groups; the cardiac death rate was 0.9%/year and 1.15%/year in the regadenoson and adenosine groups (HR: 0.77; 95% CI: 0.42 to 1.43; p = 0.404) in the pre-match sample and 0.5%/year and 0.7%/year in the matched groups, respectively (HR: 0.83; 95% CI: 0.25 to 2.73; p = 0.763). CONCLUSIONS Major cardiac events are infrequent in patients with normal regadenoson MPI. These findings provide assurance that normal MPI using a simpler stress protocol with regadenoson provides prognostic data similar to normal adenosine MPI.

Left ventricular mechanical dyssynchrony by phase analysis of gated single photon emission computed tomography in end-stage renal disease.

The presence and degree of left ventricular (LV) dyssynchrony in patients with end-stage renal disease (ESRD) has not been well studied. We hypothesized that these patients would be more likely to have mechanical dyssynchrony than a control cohort. The indexes of LV mechanical dyssynchrony were measured by automated analysis of gated single photon emission computed tomography myocardial perfusion imaging in 290 patients with ESRD and 109 control patients. Only patients with normal myocardial perfusion imaging findings and a narrow QRS duration were included. The following variables were derived: LV ejection fraction (EF), volume, mass, and 2 indexes of dyssynchrony, the standard deviation and bandwidth. The standard deviation and bandwidth were significantly greater in those with ESRD (23° ± 13° vs 15° ± 6° and 65° ± 40° vs 42° ± 14°, respectively, p <0.001 for each). The LV volumes and LV mass were significantly lower and LVEF significantly greater in the control group than in the patients with ESRD (p <0.001 for each). The subgroup of 217 patients with ESRD and normal LVEF also had a significantly greater standard deviation and bandwidth than did the control group (21° ± 12° and 57° ± 35°, p <0.001 for each). However, their values were lower than those of the 73 patients with ESRD and a LVEF <50% (30° ± 13° and 90° ± 45°, p <0.001 for each). Finally, 25 patients (9%) with ESRD and none of the control group had a standard deviation >43° (p = 0.01). In conclusion, patients with ESRD had significantly more mechanical dyssynchrony than did the control group, even in absence of electrical dyssynchrony and abnormal LV perfusion or function.

Relation between heart rate and left ventricular mechanical dyssynchrony in patients with end-stage renal disease.

The effect of heart rate (HR) on left ventricular (LV) mechanical dyssynchrony has not been studied by phase analysis of myocardial perfusion imaging and has yielded conflicting results by echocardiography. We measured indexes of LV dyssynchrony by automated analysis of gated single-photon emission computed tomography in 140 patients with end-stage renal disease (ESRD) and 133 subjects with normal renal function (control group). Patients with abnormal perfusion pattern or QRS duration >120 ms were excluded. HR at time of acquisition of gated images was recorded. LV ejection fraction (EF), volumes, mass, and 2 indexes of dyssynchrony, phase SD and bandwidth, were derived. Almost 50% of patients in each group had an abnormal LVEF (<50%). HR at rest ranged from 48 to 113 beats/min (75 ± 13). Patients with abnormal LVEF had a higher phase SD (30 ± 13° vs 22 ± 11° and 28 ± 16° vs 15 ± 6° for the ESRD and control groups, respectively, p <0.001 each) and higher histographic bandwidth (88 ± 44° vs 62 ± 33° and 80 ± 49° vs 43 ± 14° for the ESRD and control groups, p <0.001 each). Patients with ESRD and normal LVEF had higher SD and bandwidth than the control group (22 ± 11° vs 15 ± 6° and 62 ± 33° vs 43 ± 14°, respectively, p <0.001 each). The control and ESRD groups were divided into tertiles based on HR. The phase SD and bandwidth were similar in the first (slowest HR) and third (highest HR) tertiles in every group (p = NS). There were no significant correlations between phase SD or bandwidth and HR in either group. In conclusion, within the HR range examined in this cross-sectional study, there was no relation between HR at rest and LV dyssynchrony.

Valproate-induced hyperammonemic encephalopathy: a case report and brief review of the literature.

Almost 50 years after its discovery, valproic acid remains a mainstay in the treatment of epilepsy, both alone and in combination with other anticonvulsants. It is also associated with a hyperammonemic encephalopathy, when used in combination with other drugs. We present a case of valproate-induced hyperammonemic encephalopathy in a patient on multiple anticonvulsant and psychotropic medications. The patient presented with altered mental status and became progressively more obtunded and finally began to experience seizures. Her symptoms resolved with the discontinuation of valproic acid and with supportive care.

A unique paradoxical reaction to tuberculosis therapy: case report and brief review of the literature.

Extensive experience in the diagnosis and treatment of tuberculosis (TB) has led to treatment guidelines, which almost always result in progressive clinical improvement and cure in the compliant patient. Failure of a patient to respond as expected raises concerns of unexpected drug resistance, poor absorption, drug fever, or rarely an intense inflammatory reaction known as paradoxical reaction. Paradoxical reactions to anti-TB treatment are relatively rare in nonimmunocompromised individuals. Hepatic abscess is a very rare consequence of primary TB infection but has never been described as occurring as part of a paradoxical reaction. We present a case of a unique paradoxical reaction to initiation of TB treatment.

COMPARISON OF AUTOMATED QUANTITATIVE MYOCARDIAL PERFUSION IMAGING UTILIZING THREE SOFTWARE PACKAGES

Myocardial perfusion imaging (MPI) is widely utilized for assessment of myocardial ischemia and function. This study compared 3 commonly used software programs that quantitate myocardial perfusion defect size (PDS) and left ventricular (LV) volumes and ejection fraction (EF). MPI scans of 100

NET RECLASSIFICATION IMPROVEMENT OF CARDIOVASCULAR RISK IN PATIENTS WITH NORMAL MYOCARDIAL PERFUSION IMAGING USING HEART RATE RESPONSE TO VASODILATOR STRESS

Methods: We studied 1,000 consecutive patients each with normal regadenoson and adenosine MPI. Traditional risk stratification was performed using Adult Treatment Panel III (ATPIII) framework into low (< 6%), intermediate (6 20%), and high (> 20%) risk categories. Patients were further stratified by HRR into tertiles specific to each vasodilator (regadenoson <21%, 21-37% and >37% and for adenosine, <16%, 16-32% and >32%). The outcomes were all-cause mortality and major adverse cardiac events (MACE, cardiac death or non-fatal MI). Follow-up was censored at 2 years from MPI.

Amiodarone-induced thrombosis: a case series and brief review of the literature.

Amiodarone is used extensively in clinical practice for the treatment of arrhythmias but is associated with a number of well-known side effects. We present 3 cases of extensive thrombosis occurring secondary to intravenous amiodarone. In cases like these, amiodarone must be stopped immediately and patients started on appropriate anticoagulation therapy. Providing education to nursing and pharmacy staff regarding the administration of IV amiodarone and the necessity of defining institutional guidelines are central to decreasing the risk of complications from using this widely available antiarrhythmic agent.